< draft-arkko-pppext-eap-aka-11.txt		draft-arkko-pppext-eap-aka-12.txt >
			Network Working Group J. Arkko
			Internet-Draft Ericsson
			Expires: October 4, 2004 H. Haverinen
			Nokia
			April 5, 2004
	Network Working Group J. Arkko		Extensible Authentication Protocol Method for UMTS Authentication and
	Internet Draft Ericsson		Key Agreement (EAP-AKA)
	Document: draft-arkko-pppext-eap-aka-11.txt H. Haverinen		draft-arkko-pppext-eap-aka-12.txt
	Expires: 27 April, 2004 Nokia
	27 October, 2003
	EAP AKA Authentication
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is subject to all provisions		This document is an Internet-Draft and is in full conformance with
	of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
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			Copyright Notice
			Copyright (C) The Internet Society (2004). All Rights Reserved.
	Abstract		Abstract
	This document specifies an Extensible Authentication Protocol (EAP)		This document specifies an Extensible Authentication Protocol (EAP)
	mechanism for authentication and session key distribution using the		mechanism for authentication and session key distribution using the
	Universal Mobile Telecommunications System (UMTS) Authentication and		Universal Mobile Telecommunications System (UMTS) Authentication and
	Key Agreement (AKA) mechanism. UMTS AKA is based on symmetric keys,		Key Agreement (AKA) mechanism. UMTS AKA is based on symmetric keys,
	and runs typically in a UMTS Subscriber Identity Module, a smart		and runs typically in a UMTS Subscriber Identity Module, a smart card
	card like device.		like device.
	EAP AKA includes optional identity privacy support and an optional		EAP-AKA includes optional identity privacy support, optional result
	re-authentication procedure.		indications, and an optional fast re-authentication procedure.
	Table of Contents		Table of Contents
	Status of this Memo................................................1		1. Introduction and Motivation . . . . . . . . . . . . . . . . 4
	Abstract...........................................................1		2. Terms and Conventions Used in This Document . . . . . . . . 5
	1. Introduction and Motivation.....................................3		3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . 8
	2. Terms and Conventions Used in This Document.....................4		4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . 12
	3. Protocol Overview...............................................6		4.1 Identity Management . . . . . . . . . . . . . . . . . . . . 13
	4. Operation......................................................11		4.1.1 Format, Generation and Usage of Peer Identities . . . . . . 13
			4.1.2 Communicating the Peer Identity to the Server . . . . . . . 19
	EAP AKA Authentication 27 October, 2003		4.1.3 Message Sequence Examples (Informative) . . . . . . . . . . 24
			4.2 Fast Re-authentication . . . . . . . . . . . . . . . . . . . 30
	4.1. Identity Management..........................................11		4.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . 30
	4.2. Re-authentication............................................25		4.2.2 Comparison to UMTS AKA . . . . . . . . . . . . . . . . . . . 31
	4.3. EAP/AKA Notifications........................................31		4.2.3 Fast Re-authentication Identity . . . . . . . . . . . . . . 32
	4.4. Error Cases..................................................32		4.2.4 Fast Re-authentication Procedure . . . . . . . . . . . . . . 33
	4.5. Key Generation...............................................34		4.2.5 Fast Re-authentication Procedure when Counter is Too
	5. Message Format and Protocol Extensibility......................35		Small . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
	5.1. Message Format...............................................35		4.3 EAP-AKA Notifications . . . . . . . . . . . . . . . . . . . 37
	5.2. Protocol Extensibility.......................................37		4.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . 37
	6. Messages.......................................................37		4.3.2 Result Indications . . . . . . . . . . . . . . . . . . . . . 38
	6.1. EAP-Request/AKA-Identity.....................................37		4.4 Error Cases . . . . . . . . . . . . . . . . . . . . . . . . 39
	6.2. EAP-Response/AKA-Identity....................................38		4.4.1 Peer Operation . . . . . . . . . . . . . . . . . . . . . . . 39
	6.3. EAP-Request/AKA-Challenge....................................38		4.4.2 Server Operation . . . . . . . . . . . . . . . . . . . . . . 40
	6.4. EAP-Response/AKA-Challenge...................................39		4.4.3 EAP-Failure . . . . . . . . . . . . . . . . . . . . . . . . 40
	6.5. EAP-Response/AKA-Authentication-Reject.......................39		4.4.4 EAP-Success . . . . . . . . . . . . . . . . . . . . . . . . 41
	6.6. EAP-Response/AKA-Synchronization-Failure.....................39		4.5 Key Generation . . . . . . . . . . . . . . . . . . . . . . . 42
	6.7. EAP-Request/AKA-Reauthentication.............................39		5. Message Format and Protocol Extensibility . . . . . . . . . 44
	6.8. EAP-Response/AKA-Reauthentication............................40		5.1 Message Format . . . . . . . . . . . . . . . . . . . . . . . 44
	6.9. EAP-Response/AKA-Client-Error................................40		5.2 Protocol Extensibility . . . . . . . . . . . . . . . . . . . 45
	6.10. EAP-Request/AKA-Notification................................40		6. Messages . . . . . . . . . . . . . . . . . . . . . . . . . . 46
	6.11. EAP-Response/AKA-Notification...............................41		6.1 EAP-Request/AKA-Identity . . . . . . . . . . . . . . . . . . 46
	7. Attributes.....................................................41		6.2 EAP-Response/AKA-Identity . . . . . . . . . . . . . . . . . 46
	7.1. Table of Attributes..........................................41		6.3 EAP-Request/AKA-Challenge . . . . . . . . . . . . . . . . . 47
	7.2. AT_MAC.......................................................42		6.4 EAP-Response/AKA-Challenge . . . . . . . . . . . . . . . . . 47
	7.3. AT_IV, AT_ENCR_DATA and AT_PADDING...........................43		6.5 EAP-Response/AKA-Authentication-Reject . . . . . . . . . . . 48
	7.4. AT_CHECKCODE.................................................45		6.6 EAP-Response/AKA-Synchronization-Failure . . . . . . . . . . 48
	7.5. AT_PERMANENT_ID_REQ..........................................47		6.7 EAP-Request/AKA-Reauthentication . . . . . . . . . . . . . . 49
	7.6. AT_ANY_ID_REQ................................................47		6.8 EAP-Response/AKA-Reauthentication . . . . . . . . . . . . . 49
	7.7. AT_FULLAUTH_ID_REQ...........................................47		6.9 EAP-Response/AKA-Client-Error . . . . . . . . . . . . . . . 50
	7.8. AT_IDENTITY..................................................48		6.10 EAP-Request/AKA-Notification . . . . . . . . . . . . . . . . 50
	7.9. AT_RAND......................................................48		6.11 EAP-Response/AKA-Notification . . . . . . . . . . . . . . . 50
	7.10. AT_AUTN.....................................................49		7. Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 51
	7.11. AT_RES......................................................49		7.1 Table of Attributes . . . . . . . . . . . . . . . . . . . . 51
	7.12. AT_AUTS.....................................................49		7.2 AT_PERMANENT_ID_REQ . . . . . . . . . . . . . . . . . . . . 52
	7.13. AT_NEXT_PSEUDONYM...........................................50		7.3 AT_ANY_ID_REQ . . . . . . . . . . . . . . . . . . . . . . . 52
	7.14. AT_NEXT_REAUTH_ID...........................................50		7.4 AT_FULLAUTH_ID_REQ . . . . . . . . . . . . . . . . . . . . . 53
	7.15. AT_COUNTER..................................................51		7.5 AT_IDENTITY . . . . . . . . . . . . . . . . . . . . . . . . 53
	7.16. AT_COUNTER_TOO_SMALL........................................51		7.6 AT_RAND . . . . . . . . . . . . . . . . . . . . . . . . . . 54
	7.17. AT_NONCE_S..................................................51		7.7 AT_AUTN . . . . . . . . . . . . . . . . . . . . . . . . . . 54
	7.18. AT_NOTIFICATION.............................................52		7.8 AT_RES . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
	7.19. AT_CLIENT_ERROR_CODE........................................53		7.9 AT_AUTS . . . . . . . . . . . . . . . . . . . . . . . . . . 55
	8. IANA and Protocol Numbering Considerations.....................53		7.10 AT_NEXT_PSEUDONYM . . . . . . . . . . . . . . . . . . . . . 55
	9. Security Considerations........................................54		7.11 AT_NEXT_REAUTH_ID . . . . . . . . . . . . . . . . . . . . . 56
	9.1. Identity Protection..........................................55		7.12 AT_IV, AT_ENCR_DATA and AT_PADDING . . . . . . . . . . . . . 56
	9.2. Mutual Authentication........................................55		7.13 AT_CHECKCODE . . . . . . . . . . . . . . . . . . . . . . . . 58
	9.3. Key Derivation...............................................55		7.14 AT_RESULT_IND . . . . . . . . . . . . . . . . . . . . . . . 60
	9.4. Brute-Force and Dictionary Attacks...........................55		7.15 AT_MAC . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
	9.5. Integrity Protection, Replay Protection and Confidentiality..55		7.16 AT_COUNTER . . . . . . . . . . . . . . . . . . . . . . . . . 62
			7.17 AT_COUNTER_TOO_SMALL . . . . . . . . . . . . . . . . . . . . 62
	EAP AKA Authentication 27 October, 2003		7.18 AT_NONCE_S . . . . . . . . . . . . . . . . . . . . . . . . . 62
			7.19 AT_NOTIFICATION . . . . . . . . . . . . . . . . . . . . . . 63
	9.6. Negotiation Attacks..........................................56		7.20 AT_CLIENT_ERROR_CODE . . . . . . . . . . . . . . . . . . . . 64
	9.7. Fast Reconnect...............................................56		8. IANA and Protocol Numbering Considerations . . . . . . . . . 64
	9.8. Acknowledged Result Indications..............................56		9. Security Considerations . . . . . . . . . . . . . . . . . . 66
	9.9. Man-in-the-middle Attacks....................................57		9.1 Identity Protection . . . . . . . . . . . . . . . . . . . . 66
	9.10. Generating Random Numbers...................................57		9.2 Mutual Authentication . . . . . . . . . . . . . . . . . . . 66
	10. Security Claims...............................................57		9.3 Flooding the Authentication Centre . . . . . . . . . . . . . 66
	11. Intellectual Property Right Notices...........................58		9.4 Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 67
	Acknowledgements and Contributions................................58		9.5 Brute-Force and Dictionary Attacks . . . . . . . . . . . . . 67
	Authors' Addresses................................................58		9.6 Protection, Replay Protection and Confidentiality . . . . . 67
	Annex A. Pseudo-Random Number Generator...........................59		9.7 Negotiation Attacks . . . . . . . . . . . . . . . . . . . . 68
			9.8 Protected Result Indications . . . . . . . . . . . . . . . . 68
			9.9 Man-in-the-middle Attacks . . . . . . . . . . . . . . . . . 69
			9.10 Generating Random Numbers . . . . . . . . . . . . . . . . . 69
			10. Security Claims . . . . . . . . . . . . . . . . . . . . . . 69
			11. Acknowledgements and Contributions . . . . . . . . . . . . . 70
			Normative References . . . . . . . . . . . . . . . . . . . . 71
			Informative References . . . . . . . . . . . . . . . . . . . 72
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 73
			A. Pseudo-Random Number Generator . . . . . . . . . . . . . . . 73
			Intellectual Property and Copyright Statements . . . . . . . 74
	1. Introduction and Motivation		1. Introduction and Motivation
	This document specifies an Extensible Authentication Protocol (EAP)		This document specifies an Extensible Authentication Protocol (EAP)
	mechanism for authentication and session key distribution using the		mechanism for authentication and session key distribution using the
	UMTS AKA authentication mechanism [TS 33.102]. UMTS is a global		UMTS AKA authentication mechanism [TS 33.102]. UMTS is a global third
	third generation mobile network standard.		generation mobile network standard.
	AKA is based on challenge-response mechanisms and symmetric		AKA is based on challenge-response mechanisms and symmetric
	cryptography. AKA typically runs in a UMTS Subscriber Identity		cryptography. AKA typically runs in a UMTS Subscriber Identity Module
	Module (USIM). Compared to the GSM mechanism, UMTS AKA provides		(USIM). Compared to the GSM mechanism, UMTS AKA provides
	substantially longer key lengths and mutual authentication.		substantially longer key lengths and mutual authentication.
	The introduction of AKA inside EAP allows several new applications.		The introduction of AKA inside EAP allows several new applications.
	These include the following:		These include the following:
	- The use of the AKA also as a secure PPP authentication method in		o The use of the AKA also as a secure PPP authentication method in
	devices that already contain an USIM.		devices that already contain an USIM.
			o The use of the third generation mobile network authentication
	- The use of the third generation mobile network authentication		infrastructure in the context of wireless LANs
	infrastructure in the context of wireless LANs		o Relying on AKA and the existing infrastructure in a seamless way
			with any other technology that can use EAP.
	- Relying on AKA and the existing infrastructure in a seamless way
	with any other technology that can use EAP.
	AKA works in the following manner:		AKA works in the following manner:
	- The USIM and the home environment have agreed on a secret key		o The USIM and the home environment have agreed on a secret key
	beforehand.		beforehand.
			o The actual authentication process starts by having the home
	- The actual authentication process starts by having the home		environment produce an authentication vector, based on the secret
	environment produce an authentication vector, based on the secret		key and a sequence number. The authentication vector contains a
	key and a sequence number. The authentication vector contains a		random part RAND, an authenticator part AUTN used for
	random part RAND, an authenticator part AUTN used for		authenticating the network to the USIM, an expected result part
	authenticating the network to the USIM, an expected result part		XRES, a session key for integrity check IK, and a session key for
	XRES, a session key for integrity check IK, and a session key for		encryption CK.
	encryption CK.		o The RAND and the AUTN are delivered to the USIM.
			o The USIM verifies the AUTN, again based on the secret key and the
	- The RAND and the AUTN are delivered to the USIM.		sequence number. If this process is successful (the AUTN is valid
			and the sequence number used to generate AUTN is within the
	- The USIM verifies the AUTN, again based on the secret key and the		correct range), the USIM produces an authentication result, RES
	sequence number. If this process is successful (the AUTN is valid		and sends this to the home environment.
			o The home environment verifies the correct result from the USIM. If
	EAP AKA Authentication 27 October, 2003		the result is correct, IK and CK can be used to protect further
			communications between the USIM and the home environment.
	and the sequence number used to generate AUTN is within the
	correct range), the USIM produces an authentication result, RES
	and sends this to the home environment.
	- The home environment verifies the correct result from the USIM. If
	the result is correct, IK and CK can be used to protect further
	communications between the USIM and the home environment.
	When verifying AUTN, the USIM may detect that the sequence number		When verifying AUTN, the USIM may detect that the sequence number the
	the network uses is not within the correct range. In this case, the		network uses is not within the correct range. In this case, the USIM
	USIM calculates a sequence number synchronization parameter AUTS and		calculates a sequence number synchronization parameter AUTS and sends
	sends it to the network. AKA authentication may then be retried with		it to the network. AKA authentication may then be retried with a new
	a new authentication vector generated using the synchronized		authentication vector generated using the synchronized sequence
	sequence number.		number.
	For a specification of the AKA mechanisms and how the cryptographic		For a specification of the AKA mechanisms and how the cryptographic
	values AUTN, RES, IK, CK and AUTS are calculated, see [TS 33.102].		values AUTN, RES, IK, CK and AUTS are calculated, see [TS 33.102].
	In EAP AKA, the EAP server node obtains the authentication vectors,		In EAP-AKA, the EAP server node obtains the authentication vectors,
	compares RES and XRES, and uses CK and IK in key derivation.		compares RES and XRES, and uses CK and IK in key derivation.
	In the third generation mobile networks, AKA is used both for radio		In the third generation mobile networks, AKA is used both for radio
	network authentication and IP multimedia service authentication		network authentication and IP multimedia service authentication
	purposes. Different user identities and formats are used for these;		purposes. Different user identities and formats are used for these;
	the radio network uses the International Mobile Subscriber		the radio network uses the International Mobile Subscriber Identifier
	Identifier (IMSI), whereas the IP multimedia service uses the		(IMSI), whereas the IP multimedia service uses the Network Access
	Network Access Identifier (NAI) [RFC 2486].		Identifier (NAI) [RFC2486].
	2. Terms and Conventions Used in This Document		2. Terms and Conventions Used in This Document
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC 2119].		document are to be interpreted as described in [RFC2119].
	The terms and abbreviations "authenticator", "backend authentication		The terms and abbreviations "authenticator", "backend authentication
	server", "EAP server", "Silently Discard", "Master Session Key		server", "EAP server", "peer", "Silently Discard", "Master Session
	(MSK)", and "Extended Master Session Key (EMSK)" in this document		Key (MSK)", and "Extended Master Session Key (EMSK)" in this document
	are to be interpreted as described in [EAP].		are to be interpreted as described in [EAP].
	This document frequently uses the following terms and abbreviations:		This document frequently uses the following terms and abbreviations:
	AAA protocol		AAA protocol
	Authentication, Authorization and Accounting protocol		Authentication, Authorization and Accounting protocol
	AKA		AKA
	Authentication and Key Agreement		Authentication and Key Agreement
	EAP AKA Authentication 27 October, 2003
	AuC		AuC
	Authentication Centre. The mobile network element that can		Authentication Centre. The mobile network element that can
	authenticate subscribers either in GSM or in UMTS networks.		authenticate subscribers either in GSM or in UMTS networks.
	EAP		EAP
	Extensible Authentication Protocol [EAP].		Extensible Authentication Protocol
			[EAP]
	GSM		GSM
			Global System for Mobile communications.
	Global System for Mobile communications.
	NAI		NAI
	Network Access Identifier [RFC 2486].		Network Access Identifier
			[RFC2486]
	AUTN		AUTN
	Authentication value generated by the AuC which together with the		Authentication value generated by the AuC which together with the
	RAND authenticates the server to the peer, 128 bits [TS 33.102].		RAND authenticates the server to the peer, 128 bits
			[TS 33.102]
	AUTS		AUTS
	A value generated by the peer upon experiencing a synchronization		A value generated by the peer upon experiencing a synchronization
	failure, 112 bits.		failure, 112 bits.
	Permanent Identity		Fast Re-authentication Identity
	The permanent identity of the peer, including an NAI realm		A fast re-authentication identity of the peer, including an NAI realm
	portion in environments where a realm is used. The permanent		portion in environments where a realm is used. Used on re-
	identity is usually based on the IMSI. Used on full		authentication only.
	authentication only.
	Permanent Username		Fast Re-authentication Username
	The username portion of permanent identity, ie. not including any		The username portion of fast re-authentication identity, ie. not
	realm portions.		including any realm portions.
	Pseudonym Identity		Nonce
	A pseudonym identity of the peer, including an NAI realm portion		A value that is used at most once or that is never repeated
	in environments where a real is used. Used on full authentication		within the same cryptographic context. In general, a nonce can be
	only.		predictable (e.g. a counter) or unpredictable (e.g. a random value).
			Since some cryptographic properties may depend on the randomness of
			the nonce, attention should be paid to whether a nonce is required
			to be random or not. In this document, the term nonce is only
			used to denote random nonces, and it is not used to denote counters.
	Pseudonym Username		Permanent Identity
	The username portion of pseudonym identity, ie. not including any		The permanent identity of the peer, including an NAI realm
	realm portions.		portion in environments where a realm is used. The permanent
			identity is usually based on the IMSI. Used on full
			authentication only.
	EAP AKA Authentication 27 October, 2003		Permanent Username
			The username portion of permanent identity, ie. not including any
			realm portions.
	Re-authentication Identity		Pseudonym Identity
	A re-authentication identity of the peer, including an NAI realm		A pseudonym identity of the peer, including an NAI realm portion
	portion in environments where a real is used. Used on re-		in environments where a realm is used. Used on full authentication
	authentication only.		only.
	Re-authentication Username		Pseudonym Username
	The username portion of re-authentication identity, ie. not		The username portion of pseudonym identity, ie. not including any
	including any realm portions.		realm portions.
	RAND		RAND
	Random number generated by the AuC, 128 bits [TS 33.102].		Random number generated by the AuC, 128 bits
			[TS 33.102]
			.
	RES		RES
	Authentication result from the peer, which together with the RAND		Authentication result from the peer, which together with the RAND
	authenticates the peer to the server, 128 bits [TS 33.102].		authenticates the peer to the server, 128 bits
			[TS 33.102]
	SQN		SQN
	Sequence number used in the authentication process, 48 bits [TS		Sequence number used in the authentication process, 48 bits
	33.102].		[TS 33.102]
	SIM		SIM
	Subscriber Identity Module. The SIM is an application		Subscriber Identity Module. The SIM is traditionally a smart
	traditionally resident on smart cards distributed by GSM		card distributed by a GSM operator.
	operators.
	SRES		SRES
	The authentication result parameter in GSM, corresponds to the		The authentication result parameter in GSM, corresponds to the
	RES parameter in UMTS aka, 32 bits.		RES parameter in UMTS aka, 32 bits.
	USIM		USIM
	UMTS Subscriber Identity Module. USIM is an application that is		UMTS Subscriber Identity Module. USIM is an application that is
	resident e.g. on smart cards distributed by UMTS operators.		resident e.g. on smart cards distributed by UMTS operators.
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
	this document are to be interpreted as described in [RFC 2119]
	3. Protocol Overview		3. Protocol Overview
	The message flow below shows the basic successful full		Figure 1 shows the basic successful full authentication exchange in
	authentication exchange in EAP AKA. At the minimum, EAP AKA uses two		EAP-AKA, when optional result indications are not used. The
			authenticator typically communicates with an EAP server that is
			located on a backend authentication server using an AAA protocol. The
			authenticator shown in the figure is often simply relaying EAP
			messages to and from the EAP server, but these back end AAA
			communications are not shown. At the minimum, EAP-AKA uses two
	roundtrips to authorize the user and generate session keys. As in		roundtrips to authorize the user and generate session keys. As in
	other EAP schemes, an identity request/response message pair is		other EAP schemes, an identity request/response message pair is
	usually exchanged first. On full authentication, the peer's identity		usually exchanged first. On full authentication, the peer's identity
	response includes either the user's International Mobile Subscriber		response includes either the user's International Mobile Subscriber
	EAP AKA Authentication 27 October, 2003
	Identity (IMSI), or a temporary identity (pseudonym) if identity		Identity (IMSI), or a temporary identity (pseudonym) if identity
	privacy is in effect, as specified in Section 4.1. (As specified in		privacy is in effect, as specified in Section 4.1. (As specified in
	[EAP], the initial identity request is not required, and MAY be		[EAP], the initial identity request is not required, and MAY be
	bypassed in cases where the network can presume the identity, such		bypassed in cases where the network can presume the identity, such as
	as when using leased lines, dedicated dial-ups, etc. Please see also		when using leased lines, dedicated dial-ups, etc. Please see also
	Section 4.1.2 for specification how to obtain the identity via EAP		Section 4.1.2 for specification how to obtain the identity via EAP
	AKA messages.)		AKA messages.)
			After obtaining the subscriber identity, the EAP server obtains an
			authentication vector (RAND, AUTN, RES, CK, IK) for use in
			authenticating the subscriber. From the vector, the EAP server
			derives the keying material, as specified in Section 4.5. The vector
			may be obtained by contacting an Authentication Centre (AuC) on the
			UMTS network; per UMTS specifications, several vectors may be
			obtained at a time. Vectors may be stored in the EAP server for use
			at a later time, but they may not be reused.
	Next, the EAP server starts the actual AKA protocol by sending an		Next, the EAP server starts the actual AKA protocol by sending an
	EAP-Request/AKA-Challenge message. EAP AKA packets encapsulate		EAP-Request/AKA-Challenge message. EAP-AKA packets encapsulate
	parameters in attributes, encoded in a Type, Length, Value format.		parameters in attributes, encoded in a Type, Length, Value format.
	The packet format and the use of attributes are specified in Section		The packet format and the use of attributes are specified in Section
	5. The EAP-Request/AKA-Challenge message contains a random number		5. The EAP-Request/AKA-Challenge message contains a RAND random
	(AT_RAND) and a network authentication token (AT_AUTN), and a		number (AT_RAND) and a network authentication token (AT_AUTN), and a
	message authentication code AT_MAC. The EAP-Request/AKA-Challenge		message authentication code AT_MAC. The EAP-Request/AKA-Challenge
	message MAY optionally contain encrypted data, which is used for		message MAY optionally contain encrypted data, which is used for
	identity privacy and re-authentication support, as described in		identity privacy and fast re-authentication support, as described in
	Section 4.1. The AT_MAC attribute contains a message authentication		Section 4.1. The AT_MAC attribute contains a message authentication
	code covering the EAP packet. The encrypted data is not shown in the		code covering the EAP packet. The encrypted data is not shown in the
	figures of this section.		figures of this section.
	The peer runs the AKA algorithm (typically using a USIM) and		The peer runs the AKA algorithm (typically using a USIM) and verifies
	verifies the AUTN. If this is successful, the peer is talking to a		the AUTN. If this is successful, the peer is talking to a legitimate
	legitimate EAP server and proceeds to send the EAP-Response/AKA-		EAP server and proceeds to send the EAP-Response/AKA-Challenge. This
	Challenge. This message contains a result parameter that allows the		message contains a result parameter that allows the EAP server in
	EAP server in turn to authenticate the peer, and the AT_MAC		turn to authenticate the peer, and the AT_MAC attribute to integrity
	attribute to integrity protect the EAP message.		protect the EAP message.
	EAP AKA Authentication 27 October, 2003		The EAP server verifies that the RES and the MAC in the EAP-Response/
			AKA-Challenge packet are correct. Because protected success
			indications are not used in this example, the EAP server sends the
			EAP-Success packet, indicating that the authentication was
			successful. (Protected success indications are discussed in Section
			4.3.2.) The EAP server may also include derived keying material in
			the message it sends to the authenticator. The peer has derived the
			same keying material, so the authenticator does not forward the
			keying material to the peer along with EAP-Success.
	Peer Authenticator		Peer Authenticator
	| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes user's NAI) |		| (Includes user's NAI) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server runs UMTS algorithms, |		| | Server runs UMTS algorithms, |
	| | generates RAND and AUTN. |		| | generates RAND and AUTN. |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Challenge |		| EAP-Request/AKA-Challenge |
	| (AT_RAND, AT_AUTN, AT_MAC) |		| (AT_RAND, AT_AUTN, AT_MAC) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	+-------------------------------------+ |		+-------------------------------------+ |
	| Peer runs UMTS algorithms on USIM, | |		| Peer runs UMTS algorithms on USIM, | |
	| verifies AUTN and MAC, derives RES | |		| verifies AUTN and MAC, derives RES | |
	| and session key | |		| and session key | |
	+-------------------------------------+ |		+-------------------------------------+ |
	| |
	| EAP-Response/AKA-Challenge |		| EAP-Response/AKA-Challenge |
	| (AT_RES, AT_MAC) |		| (AT_RES, AT_MAC) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +--------------------------------+		| +--------------------------------+
	| | Server checks the given RES, |		| | Server checks the given RES, |
	| | and MAC and finds them correct.|		| | and MAC and finds them correct.|
	| +--------------------------------+		| +--------------------------------+
	| |
	| EAP-Success |		| EAP-Success |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	The second message flow shows how the EAP server rejects the Peer		Figure 1: EAP-AKA full authentication procedure
	due to a failed authentication. The same flow is also used in the
	GSM compatible mode, except that the AT_AUTN attribute and AT_MAC
	attribute are not used in the messages.
	EAP AKA Authentication 27 October, 2003		Figure 2 shows how the EAP server rejects the Peer due to a failed
			authentication.
	Peer Authenticator		Peer Authenticator
	| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes user's NAI) |		| (Includes user's NAI) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server runs UMTS algorithms, |		| | Server runs UMTS algorithms, |
	| | generates RAND and AUTN. |		| | generates RAND and AUTN. |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Challenge |		| EAP-Request/AKA-Challenge |
	| (AT_RAND, AT_AUTN, AT_MAC) |		| (AT_RAND, AT_AUTN, AT_MAC) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	+-------------------------------------+ |		+-------------------------------------+ |
	| Peer runs UMTS algorithms on USIM, | |		| Peer runs UMTS algorithms on USIM, | |
	| possibly verifies AUTN, and sends an| |		| possibly verifies AUTN, and sends an| |
	| invalid response | |		| invalid response | |
	+-------------------------------------+ |		+-------------------------------------+ |
	| |
	| EAP-Response/AKA-Challenge |		| EAP-Response/AKA-Challenge |
	| (AT_RES, AT_MAC) |		| (AT_RES, AT_MAC) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------------------+		| +------------------------------------------+
	| | Server checks the given RES and the MAC, |		| | Server checks the given RES and the MAC, |
	| | and finds one of them incorrct. |		| | and finds one of them incorrct. |
	| +------------------------------------------+		| +------------------------------------------+
	| |		| EAP-Request/AKA-Notification |
			|<------------------------------------------------------|
			| EAP-Response/AKA-Notification |
			|------------------------------------------------------>|
	| EAP-Failure |		| EAP-Failure |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	The next message flow shows the peer rejecting the AUTN of the EAP		Figure 2: Peer authentication fails
	server.
	The peer sends an explicit error message (EAP-Response/AKA-		Figure 3 shows the peer rejecting the AUTN of the EAP server.
	Authentication-Reject) to the EAP server, as usual in AKA when AUTN
	is incorrect. This allows the EAP server to produce the same error
	statistics as AKA in general produces in UMTS.
	EAP AKA Authentication 27 October, 2003		The peer sends an explicit error message (EAP-Response/
			AKA-Authentication-Reject) to the EAP server, as usual in AKA when
			AUTN is incorrect. This allows the EAP server to produce the same
			error statistics as AKA in general produces in UMTS.
	Peer Authenticator		Peer Authenticator
	| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes user's NAI) |		| (Includes user's NAI) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server runs UMTS algorithms, |		| | Server runs UMTS algorithms, |
	| | generates RAND and a bad AUTN|		| | generates RAND and a bad AUTN|
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Challenge |		| EAP-Request/AKA-Challenge |
	| (AT_RAND, AT_AUTN, AT_MAC) |		| (AT_RAND, AT_AUTN, AT_MAC) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	+-------------------------------------+ |		+-------------------------------------+ |
	| Peer runs UMTS algorithms on USIM | |		| Peer runs UMTS algorithms on USIM | |
	| and discovers AUTN that can not be | |		| and discovers AUTN that can not be | |
	| verified | |		| verified | |
	+-------------------------------------+ |		+-------------------------------------+ |
	| |
	| EAP-Response/AKA-Authentication-Reject |		| EAP-Response/AKA-Authentication-Reject |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| |
	| EAP-Failure |		| EAP-Failure |
	|<------------------------------------------------------|		|<------------------------------------------------------|
			Figure 3: Network authentication fails
	The AKA uses shared secrets between the Peer and the Peer's home		The AKA uses shared secrets between the Peer and the Peer's home
	operator together with a sequence number to actually perform an		operator together with a sequence number to actually perform an
	authentication. In certain circumstances it is possible for the		authentication. In certain circumstances it is possible for the
	sequence numbers to get out of sequence. Here's what happens then:		sequence numbers to get out of sequence. Figure 4 shows what happens
			then.
	EAP AKA Authentication 27 October, 2003
	Peer Authenticator		Peer Authenticator
	| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes user's NAI) |		| (Includes user's NAI) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server runs UMTS algorithms, |		| | Server runs UMTS algorithms, |
	| | generates RAND and AUTN. |		| | generates RAND and AUTN. |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Challenge |		| EAP-Request/AKA-Challenge |
	| (AT_RAND, AT_AUTN, AT_MAC) |		| (AT_RAND, AT_AUTN, AT_MAC) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	+-------------------------------------+ |		+-------------------------------------+ |
	| Peer runs UMTS algorithms on USIM | |		| Peer runs UMTS algorithms on USIM | |
	| and discovers AUTN that contains an | |		| and discovers AUTN that contains an | |
	| inappropriate sequence number | |		| inappropriate sequence number | |
	+-------------------------------------+ |		+-------------------------------------+ |
	| |
	| EAP-Response/AKA-Synchronization-Failure |		| EAP-Response/AKA-Synchronization-Failure |
	| (AT_AUTS) |		| (AT_AUTS) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +---------------------------+		| +---------------------------+
	| | Perform resynchronization |		| | Perform resynchronization |
	| | Using AUTS and |		| | Using AUTS and |
	| | the sent RAND |		| | the sent RAND |
	| +---------------------------+		| +---------------------------+
	| |		| |
	After the resynchronization process has taken place in the server		Figure 4: Sequence number synchronization
	and AAA side, the process continues by the server side sending a new
			After the resynchronization process has taken place in the server and
			AAA side, the process continues by the server side sending a new
	EAP-Request/AKA-Challenge message.		EAP-Request/AKA-Challenge message.
	In addition to the full authentication scenarios described above,		In addition to the full authentication scenarios described above,
	EAP AKA includes a re-authentication procedure, which is specified		EAP-AKA includes a fast re-authentication procedure, which is
	in Section 4.2. Re-authentication is based on keys derived on full		specified in Section 4.2. Fast re-authentication is based on keys
	authentication. If the peer has maintained state information for re-		derived on full authentication. If the peer has maintained state
	authentication and wants to use re-authentication, then the peer		information for re- authentication and wants to use fast
	indicates this by using a specific re-authentication identity		re-authentication, then the peer indicates this by using a specific
	instead of the permanent identity or a pseudonym identity. The re-		fast re-authentication identity instead of the permanent identity or
	authentication procedure is described in Section 4.2.		a pseudonym identity. The fast re-authentication procedure is
			described in Section 4.2.
	4. Operation		4. Operation
			4.1 Identity Management
	4.1. Identity Management		4.1.1 Format, Generation and Usage of Peer Identities
	4.1.1. Format, Generation and Usage of Peer Identities
	EAP AKA Authentication 27 October, 2003
	General		4.1.1.1 General
	In the beginning of EAP authentication, the Authenticator or the EAP		In the beginning of EAP authentication, the Authenticator or the EAP
	server usually issues the EAP-Request/Identity packet to the peer.		server usually issues the EAP-Request/Identity packet to the peer.
	The peer responds with EAP-Response/Identity, which contains the		The peer responds with EAP-Response/Identity, which contains the
	user's identity. The formats of these packets are specified in		user's identity. The formats of these packets are specified in [EAP].
	[EAP].
	UMTS subscribers are identified with the International Mobile		UMTS subscribers are identified with the International Mobile
	Subscriber Identity (IMSI) [TS 23.003]. The IMSI is composed of a		Subscriber Identity (IMSI) [TS 23.003]. The IMSI is composed of a
	three digit Mobile Country Code (MCC), a two or three digit Mobile		three digit Mobile Country Code (MCC), a two or three digit Mobile
	Network Code (MNC) and a not more than 10 digit Mobile Subscriber		Network Code (MNC) and a not more than 10 digit Mobile Subscriber
	Identification Number (MSIN). In other words, the IMSI is a string		Identification Number (MSIN). In other words, the IMSI is a string of
	of not more than 15 digits. MCC and MNC uniquely identify the GSM		not more than 15 digits. MCC and MNC uniquely identify the GSM
	operator and help identify the AuC from which the authentication		operator and help identify the AuC from which the authentication
	vectors need to be retrieved for this subscriber.		vectors need to be retrieved for this subscriber.
	Internet AAA protocols identify users with the Network Access		Internet AAA protocols identify users with the Network Access
	Identifier (NAI) [RFC 2486]. When used in a roaming environment, the		Identifier (NAI) [RFC2486]. When used in a roaming environment, the
	NAI is composed of a username and a realm, separated with "@"		NAI is composed of a username and a realm, separated with "@"
	(username@realm). The username portion identifies the subscriber		(username@realm). The username portion identifies the subscriber
	within the realm.		within the realm.
	This section specifies the peer identity format used in EAP/AKA. In		This section specifies the peer identity format used in EAP-AKA. In
	this document, the term identity or peer identity refers to the		this document, the term identity or peer identity refers to the whole
	whole identity string that is used to identify the peer. The peer		identity string that is used to identify the peer. The peer identity
	identity may include a realm portion. "Username" refers to the		may include a realm portion. "Username" refers to the portion of the
	portion of the peer identity that identifies the user, i.e. the		peer identity that identifies the user, i.e. the username does not
	username does not include the realm portion.		include the realm portion.
	Identity Privacy Support		4.1.1.2 Identity Privacy Support
	EAP/AKA includes optional identity privacy (anonymity) support that		EAP-AKA includes optional identity privacy (anonymity) support that
	can be used to hide the cleartext permanent identity and thereby to		can be used to hide the cleartext permanent identity and thereby to
	make the subscriber's EAP exchanges untraceable to eavesdroppers.		make the subscriber's EAP exchanges untraceable to eavesdroppers.
	Because the permanent identity never changes, revealing it would		Because the permanent identity never changes, revealing it would help
	help observers to track the user. The permanent identity is usually		observers to track the user. The permanent identity is usually based
	based on the IMSI, which may further help the tracking, because the		on the IMSI, which may further help the tracking, because the same
	same identifier may used in other contexts as well. Identity privacy		identifier may be used in other contexts as well. Identity privacy is
	is based on temporary identities, or pseudonyms, which are		based on temporary identities, or pseudonyms, which are equivalent to
	equivalent to but separate from the Temporary Mobile Subscriber		but separate from the Temporary Mobile Subscriber Identities (TMSI)
	Identities (TMSI) that are used on cellular networks. Please see		that are used on cellular networks. Please see Section 9.1 for
	Section 9.1 for security considerations regarding identity privacy.		security considerations regarding identity privacy.
	Username Types in EAP/AKA Identities
	There are three types of usernames in EAP/AKA peer identities:		4.1.1.3 Username Types in EAP-AKA Identities
	(1) Permanent usernames. For example,		There are three types of usernames in EAP-AKA peer identities:
	0123456789098765@myoperator.com might be a valid permanent identity.
	In this example, 0123456789098765 is the permanent username.
	EAP AKA Authentication 27 October, 2003		(1) Permanent usernames. For example, 0123456789098765@myoperator.com
			might be a valid permanent identity. In this example,
			0123456789098765 is the permanent username.
	(2) Pseudonym usernames. For example, 2s7ah6n9q@myoperator.com might		(2) Pseudonym usernames. For example, 2s7ah6n9q@myoperator.com might
	be a valid pseudonym identity. In this example, 2s7ah6n9q is the		be a valid pseudonym identity. In this example, 2s7ah6n9q is the
	pseudonym username.		pseudonym username.
	(3) Re-authentication usernames. For example,		(3) Fast re-authentication usernames. For example,
	43953754a@myoperator.com might be a valid re-authentication		43953754@myoperator.com might be a valid fast re-authentication
	identity. In this case, 43953754 is the re-authentication username.		identity. In this case, 43953754 is the fast re-authentication
			username.
	The first two types of identities are only used on full		The first two types of identities are only used on full
	authentication and the last one only on re-authentication. When the		authentication and the last one only on fast re-authentication. When
	optional identity privacy support is not used, the non-pseudonym		the optional identity privacy support is not used, the non-pseudonym
	permanent identity is used on full authentication. The re-		permanent identity is used on full authentication. The fast
	authentication exchange is specified in Section 4.2.		re-authentication exchange is specified in Section 4.2.
	sername Decoration		4.1.1.4 Username Decoration
	In some environments, the peer may need to decorate the identity by		In some environments, the peer may need to decorate the identity by
	prepending or appending the username with a string, in order to		prepending or appending the username with a string, in order to
	indicate supplementary AAA routing information in addition to the		indicate supplementary AAA routing information in addition to the NAI
	NAI realm. (The usage of a NAI realm portion is not considered to be		realm. (The usage of a NAI realm portion is not considered to be
	decoration.) Username decoration is out of the scope of this		decoration.) Username decoration is out of the scope of this
	document. However, it should be noted that username decoration might		document. However, it should be noted that username decoration might
	prevent the server from recognizing a valid username. Hence,		prevent the server from recognizing a valid username. Hence, although
	although the peer MAY use username decoration in the identities the		the peer MAY use username decoration in the identities the peer
	peer includes in EAP-Response/Identity, and the EAP server MAY		includes in EAP-Response/Identity, and the EAP server MAY accept a
	accept a decorated peer username in this message, the peer or the		decorated peer username in this message, the peer or the EAP server
	EAP server MUST NOT decorate any other peer identities that are used		MUST NOT decorate any other peer identities that are used in various
	in various EAP/AKA attributes. Only the identity used in EAP-		EAP-AKA attributes. Only the identity used in EAP-Response/Identity
	Response/Identity may be decorated.		may be decorated.
	NAI Realm Portion		4.1.1.5 NAI Realm Portion
	The peer MAY include a realm portion in the peer identity, as per		The peer MAY include a realm portion in the peer identity, as per the
	the NAI format. The use of a realm portion is not mandatory.		NAI format. The use of a realm portion is not mandatory.
	If a realm is used, the realm MAY be chosen by the operator and it		If a realm is used, the realm MAY be chosen by the subscriber's home
	MAY a configurable parameter in the EAP/SIM peer implementation. In		operator and it MAY a configurable parameter in the EAP-SIM peer
	this case, the peer is typically configured with the NAI realm of		implementation. In this case, the peer is typically configured with
	the home operator. Operators MAY reserve a specific realm name for		the NAI realm of the home operator. Operators MAY reserve a specific
	EAP/AKA users. This convention makes it easy to recognize that the		realm name for EAP-AKA users. This convention makes it easy to
	NAI identifies a UMTS subscriber. Such reserved NAI realm may be		recognize that the NAI identifies a UMTS subscriber. Such reserved
	useful as a hint as to the first authentication method to use during		NAI realm may be useful as a hint as to the first authentication
	method negotiation. When the peer is using a pseudonym username		method to use during method negotiation. When the peer is using a
	instead of the permanent username, the peer selects the realm name		pseudonym username instead of the permanent username, the peer
	portion similarly as it select the realm portion when using the		selects the realm name portion similarly as it select the realm
	permanent username.		portion when using the permanent username.
	If no configured realm name is available, the peer MAY derive the		If no configured realm name is available, the peer MAY derive the
	realm name from the MCC and MNC portions of the IMSI. A recommended		realm name from the MCC and MNC portions of the IMSI. A RECOMMENDED
	way to derive the realm from the IMSI using the realm		way to derive the realm from the IMSI using the realm 3gppnetwork.org
	3gppnetwork.org will be specified in [Draft 3GPP TS 23.234].		will be specified in [Draft 3GPP TS 23.003].
	Alternatively, the realm name may be obtained by concatenating
	"mnc", the MNC digits of IMSI, ".mcc", the MCC digits of IMSI and
	".owlan.org". For example, if the IMSI is 123456789098765, and the
	EAP AKA Authentication 27 October, 2003
	MNC is three digits long, then the derived realm name is		Some old implementations derive the realm name from the IMSI by
	"mnc456.mcc123.owlan.org".		concatenating "mnc", the MNC digits of IMSI, ".mcc", the MCC digits
			of IMSI and ".owlan.org". For example, if the IMSI is
			123456789098765, and the MNC is three digits long, then the derived
			realm name is "mnc456.mcc123.owlan.org". As there are no DNS servers
			running at owlan.org, these realm names can only be used with
			manually configured AAA routing. New implementations SHOULD use the
			mechanism specified in [Draft 3GPP TS 23.003] instead of owlan.org as
			soon as the 3GPP specification is finalized.
	The IMSI is a string of digits without any explicit structure, so		The IMSI is a string of digits without any explicit structure, so the
	the peer may not be able to determine the length of the MNC portion.		peer may not be able to determine the length of the MNC portion. If
	If the peer is not able to determine whether the MNC is two or three		the peer is not able to determine whether the MNC is two or three
	digits long, the peer MAY use a 3-digit MNC. If the correct length		digits long, the peer MAY use a 3-digit MNC. If the correct length of
	of the MNC is two, then the MNC used in the realm name includes the		the MNC is two, then the MNC used in the realm name includes the
	first digit of MSIN. Hence, when configuring AAA networks for		first digit of MSIN. Hence, when configuring AAA networks for
	operators that have 2-digit MNC's, the network SHOULD also be		operators that have 2-digit MNC's, the network SHOULD also be
	prepared for realm names with incorrect 3-digit MNC's.		prepared for realm names with incorrect 3-digit MNC's.
	Format of the Permanent Username		4.1.1.6 Format of the Permanent Username
	The non-pseudonym permanent username SHOULD be derived from the		The non-pseudonym permanent username SHOULD be derived from the IMSI.
	IMSI. In this case, the permanent username MUST be of the format "0"		In this case, the permanent username MUST be of the format "0" |
	| IMSI, where the character "|" denotes concatenation. In other		IMSI, where the character "|" denotes concatenation. In other words,
	words, the first character of the username is the digit zero (ASCII		the first character of the username is the digit zero (ASCII value 30
	value 0x30), followed by the IMSI. The IMSI is an ASCII string that		hexadecimal), followed by the IMSI. The IMSI is an ASCII string that
	consists of not more than 15 decimal digits (ASCII values between		consists of not more than 15 decimal digits (ASCII values between 30
	0x30 and 0x39) as specified in [TS 23.003].		and 39 hexadecimal), one character per IMSI digit, in the order as
			specified in [TS 23.003]. For example, a permanent username derived
			from the IMSI 295023820005424 would be encoded as the ASCII string
			"0295023820005424" (byte values in hexadecimal notation: 30 32 39 35
			30 32 33 38 32 30 30 30 35 34 32 34)
	The EAP server MAY use the leading "0" as a hint to try EAP/AKA as		The EAP server MAY use the leading "0" as a hint to try EAP-AKA as
	the first authentication method during method negotiation, rather		the first authentication method during method negotiation, rather
	than for example EAP/SIM. The EAP/AKA server MAY propose EAP/AKA		than for example EAP-SIM. The EAP-AKA server MAY propose EAP-AKA even
	even if the leading character was not "0".		if the leading character was not "0".
	Alternatively, an implementation MAY choose a permanent username		Alternatively, an implementation MAY choose a permanent username that
	that is not based on the IMSI. In this case the selection of the		is not based on the IMSI. In this case the selection of the username,
	username, its format, and its processing is out of the scope of this		its format, and its processing is out of the scope of this document.
	document. In this case, the peer implementation MUST NOT prepend any		In this case, the peer implementation MUST NOT prepend any leading
	leading characters to the username.		characters to the username.
	Generating Pseudonyms and Re-authentication Identities by the Server		4.1.1.7 Generating Pseudonyms and Fast Re-authentication Identities by
			the Server
	Pseudonym usernames and re-authentication identities are generated		Pseudonym usernames and fast re-authentication identities are
	by the EAP server. The EAP server produces pseudonym usernames and		generated by the EAP server. The EAP server produces pseudonym
	re-authentication identities in an implementation-dependent manner.		usernames and fast re-authentication identities in an
	Only the EAP server needs to be able to map the pseudonym username		implementation-dependent manner. Only the EAP server needs to be able
	to the permanent identity, or to recognize a re-authentication		to map the pseudonym username to the permanent identity, or to
	identity. Regardless of construction method, the pseudonym username		recognize a fast re-authentication identity.
	MUST conform to the grammar specified for the username portion of an
	NAI. The re-authentication identity also MUST conform to the NAI		EAP-AKA includes no provisions to ensure that the same EAP server
			that generated a pseudonym username will be used on the
			authentication exchange when the pseudonym username is used. It is
			recommended that the EAP servers implement some centralized mechanism
			to allow all EAP servers of the home operator to map pseudonyms
			generated by other severs to the permanent identity. If no such
			mechanism is available, then the EAP server failing to understand a
			pseudonym issued by another server can request the peer to send the
			permanent identity.
			When issuing a fast re-authentication identity, the EAP server may
			include a realm name in the identity to make the fast
			re-authentication request be forwarded to the same EAP server.
			When generating fast re-authentication identities, the server SHOULD
			choose a fresh new fast re-authentication identity that is different
			from the previous ones used within a same reauthentication context.
			The fast re-authentication identity SHOULD include a random
			component. The random component works as a full authentication
			context identifier. A context-specific fast re-authentication
			identity can help the server to detect whether its fast
			re-authentication state information matches the peer's fast
			re-authentication state information (in other words whether the state
			information is from the same full authentication exchange). The
			random component also makes the fast re-authentication identities
			unpredictable, so an attacker cannot initiate a fast
			re-authentication exchange to get the server's EAP-Request/SIM/
			Re-authentication packet.
			Regardless of construction method, the pseudonym username MUST
			conform to the grammar specified for the username portion of an NAI.
			The fast re-authentication identity also MUST conform to the NAI
	grammar. The EAP servers that the subscribers of an operator can use		grammar. The EAP servers that the subscribers of an operator can use
	MUST ensure that the pseudonym usernames and the username portions		MUST ensure that the pseudonym usernames and the username portions
	used in re-authentication identities they generate are unique.		used in fast re-authentication identities they generate are unique.
	In any case, it is necessary that permanent usernames, pseudonym		In any case, it is necessary that permanent usernames, pseudonym
	usernames and re-authentication usernames are separate and		usernames and fast re-authentication usernames are separate and
	recognizable from each other. It is also desirable that EAP SIM and		recognizable from each other. It is also desirable that EAP-SIM and
	EAP AKA user names be recognizable from each other as an aid for the		EAP-AKA user names be recognizable from each other as an aid for the
	server to which method to offer.		server to which method to offer.
	EAP AKA Authentication 27 October, 2003
	In general, it is the task of the EAP server and the policies of its		In general, it is the task of the EAP server and the policies of its
	administrator to ensure sufficient separation in the usernames.		administrator to ensure sufficient separation in the usernames.
	Pseudonym usernames and re-authentication usernames are both		Pseudonym usernames and fast re-authentication usernames are both
	produced and used by the EAP server. The EAP server MUST compose		produced and used by the EAP server. The EAP server MUST compose
	pseudonym usernames and re-authentication usernames so that it can		pseudonym usernames and fast re-authentication usernames so that it
	recognize if a NAI username is an EAP AKA pseudonym username or an		can recognize if a NAI username is an EAP-AKA pseudonym username or
	EAP AKA re-authentication username. For instance, when the usernames		an EAP-AKA fast re-authentication username. For instance, when the
	have been derived from the IMSI, the server could use different		usernames have been derived from the IMSI, the server could use
	leading characters in the pseudonym usernames and re-authentication		different leading characters in the pseudonym usernames and fast
	usernames (e.g. the pseudonym could begin with a leading "2"		re-authentication usernames (e.g. the pseudonym could begin with a
	character). When mapping a re-authentication identity to a permanent		leading "2" character). When mapping a fast re-authentication
	identity, the server SHOULD only examine the username portion of the		identity to a permanent identity, the server SHOULD only examine the
	re-authentication identity and ignore the realm portion of the		username portion of the fast re-authentication identity and ignore
	identity.		the realm portion of the identity.
	Because the peer may fail to save a pseudonym username sent to in an		Because the peer may fail to save a pseudonym username sent to in an
	EAP-Request/AKA-Challenge, for example due to malfunction, the EAP		EAP-Request/AKA-Challenge, for example due to malfunction, the EAP
	server SHOULD maintain at least one old pseudonym username in		server SHOULD maintain at least the most recently used pseudonym
	addition to the most recent pseudonym username.		username in addition to the most recently issued pseudonym username.
			If the authentication exchange is not completed successfully, then
			the server SHOULD NOT overwrite the pseudonym username that was
			issued during the most recent successful authentication exchange.
	Transmitting Pseudonyms and Re-authentication Identities to the Peer		4.1.1.8 Transmitting Pseudonyms and Fast Re-authentication Identities to
			the Peer
	The server transmits pseudonym usernames and re-authentication		The server transmits pseudonym usernames and fast re-authentication
	identities to the peer in cipher, using the AT_ENCR_DATA attribute.		identities to the peer in cipher, using the AT_ENCR_DATA attribute.
	The EAP-Request/AKA-Challenge message MAY include an encrypted		The EAP-Request/AKA-Challenge message MAY include an encrypted
	pseudonym username and/or an encrypted re-authentication identity in		pseudonym username and/or an encrypted fast re-authentication
	the value field of the AT_ENCR_DATA attribute. Because identity		identity in the value field of the AT_ENCR_DATA attribute. Because
	privacy support and re-authentication are optional to implement, the		identity privacy support and fast re-authentication are optional to
	peer MAY ignore the AT_ENCR_DATA attribute and always use the		implement, the peer MAY ignore the AT_ENCR_DATA attribute and always
	permanent identity. On re-authentication (discussed in Section 4.2),		use the permanent identity. On fast re-authentication (discussed in
	the server MAY include a new encrypted re-authentication identity in		Section 4.2), the server MAY include a new encrypted fast
	the EAP-Request/AKA-Reauthentication message.		re-authentication identity in the EAP-Request/AKA-Reauthentication
			message.
	On receipt of the EAP-Request/AKA-Challenge, the peer MAY decrypt		On receipt of the EAP-Request/AKA-Challenge, the peer MAY decrypt the
	the encrypted data in AT_ENCR_DATA and if a pseudonym username is		encrypted data in AT_ENCR_DATA and if a pseudonym username is
	included, the peer may use the obtained pseudonym username on the		included, the peer may use the obtained pseudonym username on the
	next full authentication. If a re-authentication identity is		next full authentication. If a fast re-authentication identity is
	included, then the peer MAY save it and other re-authentication		included, then the peer MAY save it together with other fast
	state information, as discussed in Section 4.2, for the next re-		re-authentication state information, as discussed in Section 4.2, for
	authentication.		the next re- authentication.
	If the peer does not receive a new pseudonym username in the EAP-		If the peer does not receive a new pseudonym username in the EAP-
	Request/AKA-Challenge message, the peer MAY use an old pseudonym		Request/AKA-Challenge message, the peer MAY use an old pseudonym
	username instead of the permanent username on next full		username instead of the permanent username on next full
	authentication. The username portions of re-authentication		authentication. The username portions of fast re-authentication
	identities are one-time usernames, which the peer MUST NOT re-use.		identities are one-time usernames, which the peer MUST NOT re-use.
			When the peer uses a fast re-authentication identity in an EAP
			exchange, the peer MUST discard the fast re-authentication identity
			and not re-use it in another EAP authentication exchange, even if the
			authentication exchange was not completed.
	Usage of the Pseudonym by the Peer		4.1.1.9 Usage of the Pseudonym by the Peer
	When the optional identity privacy support is used on full		When the optional identity privacy support is used on full
	authentication, the peer MAY use the pseudonym username received as		authentication, the peer MAY use a pseudonym username received as
	part of the previous full authentication sequence as the username		part of a previous full authentication sequence as the username
	portion of the NAI. The peer MUST NOT modify the pseudonym username		portion of the NAI. The peer MUST NOT modify the pseudonym username
	EAP AKA Authentication 27 October, 2003
	received in AT_NEXT_PSEUDONYM. However, as discussed above, the peer		received in AT_NEXT_PSEUDONYM. However, as discussed above, the peer
	MAY need to decorate the username in some environments by appending		MAY need to decorate the username in some environments by appending
	or prepending the username with a string that indicates		or prepending the username with a string that indicates supplementary
	supplementary AAA routing information.		AAA routing information.
	When using a pseudonym username in an environment where a realm		When using a pseudonym username in an environment where a realm
	portion is used, the peer concatenates the received pseudonym		portion is used, the peer concatenates the received pseudonym
	username with the "@" character and a NAI realm portion. The		username with the "@" character and a NAI realm portion. The
	selection of the NAI realm is discussed above.		selection of the NAI realm is discussed above. The peer can select
			the realm portion similarly regardless of whether it uses the
			permanent username or a pseudonym username.
	Usage of the Re-authentication Identity by the Peer		4.1.1.10 Usage of the Fast Re-authentication Identity by the Peer
	On re-authentication, the peer uses the re-authentication identity,		On fast re-authentication, the peer uses the fast re-authentication
	received as part of the previous authentication sequence. A new re-		identity, received as part of the previous authentication sequence. A
	authentication identity may be delivered as part of both full		new fast re-authentication identity may be delivered as part of both
	authentication and re-authentication. The peer MUST NOT modify the		full authentication and fast re-authentication. The peer MUST NOT
	username part of the re-authentication identity received in		modify the username part of the fast re-authentication identity
	AT_NEXT_REAUTH_ID, except in cases when username decoration is		received in AT_NEXT_REAUTH_ID, except in cases when username
	required. Even in these cases, the "root" re-authentication username		decoration is required. Even in these cases, the "root" fast
	must not be modified, but it may be appended or prepended with		re-authentication username must not be modified, but it may be
	another string.		appended or prepended with another string.
	4.1.2. Communicating the Peer Identity to the Server		4.1.2 Communicating the Peer Identity to the Server
	General		4.1.2.1 General
	The peer identity MAY be communicated to the server with the EAP-		The peer identity MAY be communicated to the server with the
	Response/Identity message. This message MAY contain the permanent		EAP-Response/Identity message. This message MAY contain the permanent
	identity, a pseudonym identity, or a re-authentication identity. If		identity, a pseudonym identity, or a fast re-authentication identity.
	the peer uses the permanent identity or a pseudonym identity, which		If the peer uses the permanent identity or a pseudonym identity,
	the server is able to map to the permanent identity, then the		which the server is able to map to the permanent identity, then the
	authentication proceeds as discussed in the overview of Section 3.		authentication proceeds as discussed in the overview of Section 3. If
	If the peer uses a re-authentication identity, and the server		the peer uses a fast re-authentication identity, and if the fast
	recognized the identity and agrees on using re-authentication, then		re-authentication identity matches with a valid fast
	a re-authentication exchange is performed, as described in Section		re-authentication identity maintained by the server , then a fast
	4.2.		re-authentication exchange is performed, as described in Section 4.2.
	The peer identity can also be transmitted from the peer to the		The peer identity can also be transmitted from the peer to the server
	server using EAP/AKA messages instead of EAP-Response/Identity. In		using EAP-AKA messages instead of EAP-Response/Identity. In this
	this case, the server includes an identity requesting attribute		case, the server includes an identity requesting attribute
	(AT_ANY_ID_REQ, AT_FULLAUTH_ID_REQ or AT_PERMANENT_ID_REQ) in the		(AT_ANY_ID_REQ, AT_FULLAUTH_ID_REQ or AT_PERMANENT_ID_REQ) in the
	EAP-Request/AKA-Identity message, and the peer includes the		EAP-Request/AKA-Identity message, and the peer includes the
	AT_IDENTITY attribute, which contains the peer's identity, in the		AT_IDENTITY attribute, which contains the peer's identity, in the
	EAP-Response/AKA-Identity message. The AT_ANY_ID_REQ attribute is a		EAP-Response/AKA-Identity message. The AT_ANY_ID_REQ attribute is a
	general identity requesting attribute, which the server uses if it		general identity requesting attribute, which the server uses if it
	does not specify which kind of an identity the peer should return in		does not specify which kind of an identity the peer should return in
	AT_IDENTITY. The server uses the AT_FULLAUTH_ID_REQ attribute to		AT_IDENTITY. The server uses the AT_FULLAUTH_ID_REQ attribute to
	request either the permanent identity or a pseudonym identity. The		request either the permanent identity or a pseudonym identity. The
	server uses the AT_PERMANENT_ID_REQ attribute to request the peer to		server uses the AT_PERMANENT_ID_REQ attribute to request the peer to
	send its permanent identity. The EAP-Request/AKA-Challenge, EAP-		send its permanent identity. The EAP-Request/AKA-Challenge,
	Response/AKA-Challenge, or the packets used on re-authentication may		EAP-Response/AKA-Challenge, or the packets used on fast
	optionally include the AT_CHECKCODE attribute, which enables the		re-authentication may optionally include the AT_CHECKCODE attribute,
	protocol peers to ensure the integrity of the AKA-Identity packets.		which enables the protocol peers to ensure the integrity of the
	AT_CHECKCODE is specified in Section 0.		AKA-Identity packets. AT_CHECKCODE is specified in Section 7.13.
	EAP AKA Authentication 27 October, 2003
	The identity format in the AT_IDENTITY attribute is the same as in		The identity format in the AT_IDENTITY attribute is the same as in
	the EAP-Response/Identity packet (except that identity decoration is		the EAP-Response/Identity packet (except that identity decoration is
	not allowed). The AT_IDENTITY attribute contains a permanent		not allowed). The AT_IDENTITY attribute contains a permanent
	identity, a pseudonym identity or a re-authentication identity.		identity, a pseudonym identity or a fast re-authentication identity.
	Obtaining the subscriber identity via EAP/AKA messages is useful if		Obtaining the subscriber identity via EAP-AKA messages is useful if
	the server does not have any EAP/AKA peer identity at the beginning		the server does not have any EAP-AKA peer identity at the beginning
	of the EAP/AKA exchange or does not recognize the identity the peer		of the EAP-AKA exchange or does not recognize the identity the peer
	used in EAP-Response/Identity. This may happen if, for example, the		used in EAP-Response/Identity. This may happen if, for example, the
	EAP-Response/Identity has been issued by some EAP method other than		EAP-Response/Identity has been issued by some EAP method other than
	EAP/AKA or if intermediate entities or software layers in the peer		EAP-AKA or if intermediate entities or software layers in the peer
	have modified the identity string in the EAP-Response/Identity		have modified the identity string in the EAP-Response/Identity
	packet. Also, some EAP layer implementations may cache the identity		packet. Also, some EAP layer implementations may cache the identity
	string from the first EAP authentication and do not obtain a new		string from the first EAP authentication and do not obtain a new
	identity string from the EAP method implementation on subsequent		identity string from the EAP method implementation on subsequent
	authentication exchanges.		authentication exchanges.
	As the identity string is used in key derivation, any of these cases		As the identity string is used in key derivation, any of these cases
	will result in failed authentication unless the EAP server uses		will result in failed authentication unless the EAP server uses
	EAP/AKA attributes to obtain an unmodified copy of the identity		EAP-AKA attributes to obtain an unmodified copy of the identity
	string. Therefore, unless the EAP server can be certain that no		string. Therefore, unless the EAP server can be certain that no
	intermediate element or software layer has modified the EAP-		intermediate element or software layer has modified the EAP-
	Response/Identity packet, the EAP server SHOULD always use the		Response/Identity packet, the EAP server MUST use the EAP-AKA
	EAP/AKA attributes to obtain the identity, even if the identity		attributes to obtain the identity, even if the identity received in
	received in EAP-Response/Identity was valid.		EAP-Response/Identity was valid.
	Please note that the EAP/AKA peer and the EAP/AKA server only		Please note that the EAP-AKA peer and the EAP-AKA server only process
	process the AT_IDENTITY attribute and entities that only pass		the AT_IDENTITY attribute and entities that only pass through EAP
	through EAP packets do not process this attribute. Hence, if the EAP		packets do not process this attribute. Hence, if the EAP server is
	server is not co-located in the authenticator, then the		not co-located in the authenticator, then the authenticator and other
	authenticator and other intermediate AAA elements (such as possible		intermediate AAA elements (such as possible AAA proxy servers) will
	AAA proxy servers) will continue to refer to the peer with the		continue to refer to the peer with the original identity from the
	original identity from the EAP-Response/Identity packet regardless		EAP-Response/Identity packet regardless of whether the AT_IDENTITY
	of whether the AT_IDENTITY attribute is used in EAP/AKA to transmit		attribute is used in EAP-AKA to transmit another identity.
	another identity.
	Choice of Identity for the EAP-Response/Identity		4.1.2.2 Choice of Identity for the EAP-Response/Identity
	If EAP/AKA peer is started upon receiving an EAP-Request/Identity		If EAP-AKA peer is started upon receiving an EAP-Request/Identity
	message, then the peer performs the following steps.		message, then the peer performs the following steps.
	If the peer has maintained re-authentication state information and		If the peer has maintained fast re-authentication state information
	if the peer wants to use re-authentication, then the peer transmits		and if the peer wants to use fast re-authentication, then the peer
	the re-authentication identity in EAP-Response/Identity.		transmits the fast re-authentication identity in EAP-Response/
			Identity.
	Else, if the peer has a pseudonym username available, then the peer		Else, if the peer has a pseudonym username available, then the peer
	transmits the pseudonym identity in EAP-Response/Identity.		transmits the pseudonym identity in EAP-Response/Identity.
	In other cases, the peer transmits the permanent identity in EAP-		In other cases, the peer transmits the permanent identity in
	Response/Identity.		EAP-Response/Identity.
	EAP AKA Authentication 27 October, 2003
	Server Operation in the Beginning of EAP/AKA Exchange		4.1.2.3 Server Operation in the Beginning of EAP-AKA Exchange
	If the EAP server has not received any identity (permanent identity,		If the EAP server has not received any EAP-AKA peer identity
	pseudonym identity or re-authentication identity) from the peer when		(permanent identity, pseudonym identity or fast re-authentication
	sending the first EAP/AKA request, or if the EAP server has received		identity) from the peer when sending the first EAP-AKA request, or if
	an EAP-Response/Identity packet but the contents do not appear to be		the EAP server has received an EAP-Response/Identity packet but the
	a valid permanent identity, pseudonym identity or a re-		contents do not appear to be a valid permanent identity, pseudonym
	authentication identity, then the server MUST request an identity		identity or a re- authentication identity, then the server MUST
	from the peer using one of the methods below.		request an identity from the peer using one of the methods below.
	The server sends the EAP-Request/AKA-Identity message with the		The server sends the EAP-Request/AKA-Identity message with the
	AT_PERMANENT_ID_REQ message to indicate that the server wants the		AT_PERMANENT_ID_REQ message to indicate that the server wants the
	peer to include the permanent identity in the AT_IDENTITY attribute		peer to include the permanent identity in the AT_IDENTITY attribute
	of the EAP-Response/AKA-Identity message. This is done in the		of the EAP-Response/AKA-Identity message. This is done in the
	following cases:		following cases:
	- The server does not support re-authentication or identity privacy.		o The server does not support fast re-authentication or identity
			privacy.
	- The server received an identity that it recognizes as a pseudonym		o The server received an identity that it recognizes as a pseudonym
	identity but the server is not able to map the pseudonym identity to		identity but the server is not able to map the pseudonym identity
	a permanent identity.		to a permanent identity.
	The server issues the EAP-Request/AKA-Identity packet with the
	AT_FULLAUTH_ID_REQ attribute to indicate that the server wants the
	peer to include a full authentication identity (pseudonym identity
	or permanent identity) in the AT_IDENTITY attribute of the EAP-
	Response/AKA-Identity message. This is done in the following cases:
	- The server does not support re-authentication and the server
	supports identity privacy
	- The server received an identity that it recognizes as a re-		o The server issues the EAP-Request/AKA-Identity packet with the
	authentication identity but the server is not able to map the re-		AT_FULLAUTH_ID_REQ attribute to indicate that the server wants the
	authentication identity to a permanent identity		peer to include a full authentication identity (pseudonym identity
			or permanent identity) in the AT_IDENTITY attribute of the
			EAP-Response/AKA-Identity message. This is done in the following
			cases:
			o The server does not support fast re-authentication and the server
			supports identity privacy
			o The server received an identity that it recognizes as a re-
			authentication identity but the server is not able to map the re-
			authentication identity to a permanent identity
	The server issues the EAP-Request/AKA-Identity packet with the		The server issues the EAP-Request/AKA-Identity packet with the
	AT_ANY_ID_REQ attribute to indicate that the server wants the peer		AT_ANY_ID_REQ attribute to indicate that the server wants the peer to
	to include an identity in the AT_IDENTITY attribute of the EAP-		include an identity in the AT_IDENTITY attribute of the EAP-Response/
	Response/SIM/Start message, and the server does not indicate any		SIM/Start message, and the server does not indicate any preferred
	preferred type for the identity. This is done in other cases, such		type for the identity. This is done in other cases, such as when the
	as when the server does not have any identity, or the server does		server does not have any identity, or the server does not recognize
	not recognize the format of a received identity.		the format of a received identity.
	Processing of EAP-Request/AKA-Identity by the Peer		4.1.2.4 Processing of EAP-Request/AKA-Identity by the Peer
	Upon receipt of an EAP-Request/AKA-Identity message, the peer MUST		Upon receipt of an EAP-Request/AKA-Identity message, the peer MUST
	perform the following steps.		perform the following steps.
	If the EAP-Request/AKA-Identity includes AT_PERMANENT_ID_REQ the		If the EAP-Request/AKA-Identity includes AT_PERMANENT_ID_REQ, and if
	peer MUST either respond with EAP-Response/AKA-Identity and include		the peer does not have a pseudonym available, then the peer MUST
	the permanent identity in AT_IDENTITY or respond with EAP-		respond with EAP-Response/AKA-Identity and include the permanent
	Response/AKA-Client-Error packet with code "unable to process		identity in AT_IDENTITY. If the peer has a pseudonym available, then
			the peer MAY refuse to send the permanent identity; hence in this
			case the peer MUST either respond with EAP-Response/AKA-Identity and
			include the permanent identity in AT_IDENTITY or respond with
			EAP-Response/AKA-Client-Error packet with code "unable to process
	packet".		packet".
	EAP AKA Authentication 27 October, 2003
	If the EAP-Request/AKA-Identity includes AT_FULL_AUTH_ID_REQ, and if		If the EAP-Request/AKA-Identity includes AT_FULL_AUTH_ID_REQ, and if
	the peer has a pseudonym available, then the peer SHOULD respond		the peer has a pseudonym available, then the peer SHOULD respond with
	with EAP-Response/AKA-Identity and includes the pseudonym identity		EAP-Response/AKA-Identity and include the pseudonym identity in
	in AT_IDENTITY. If the peer does not have a pseudonym when it		AT_IDENTITY. If the peer does not have a pseudonym when it receives
	receives this message, then the peer MUST either respond with EAP-		this message, then the peer MUST respond with EAP-Response/
	Response/AKA-Identity and include the permanent identity in		AKA-Identity and include the permanent identity in AT_IDENTITY. The
	AT_IDENTITY or respond with EAP-Response/AKA-Client-Error packet		Peer MUST NOT use a fast re-authentication identity in the
	with code "unable to process packet." The Peer MUST NOT use a re-		AT_IDENTITY attribute.
	authentication identity in the AT_IDENTITY attribute.
	If the EAP-Request/AKA-Identity includes AT_ANY_ID_REQ, and if the		If the EAP-Request/AKA-Identity includes AT_ANY_ID_REQ, and if the
	peer has maintained re-authentication state information and the peer		peer has maintained fast re-authentication state information and the
	wants to use re-authentication, then the peer responds with EAP-		peer wants to use fast re-authentication, then the peer responds with
	Response/AKA-Identity and includes the re-authentication identity in		EAP- Response/AKA-Identity and includes the fast re-authentication
	AT_IDENTITY. Else, if the peer has a pseudonym identity available,		identity in AT_IDENTITY. Else, if the peer has a pseudonym identity
	then the peer responds with EAP-Response/AKA-Identity and includes		available, then the peer responds with EAP-Response/AKA-Identity and
	the pseudonym identity in AT_IDENTITY. Else, the peer responds with		includes the pseudonym identity in AT_IDENTITY. Else, the peer
	EAP-Response/AKA-Identity and includes the permanent identity in		responds with EAP-Response/AKA-Identity and includes the permanent
	AT_IDENTITY.		identity in AT_IDENTITY.
	An EAP/AKA exchange may include several EAP/AKA-Identity rounds. The		An EAP-AKA exchange may include several EAP/AKA-Identity rounds. The
	server may issue a second EAP-Request/AKA-Identity, if it was not		server may issue a second EAP-Request/AKA-Identity, if it was not
	able to recognize the identity the peer used in the previous		able to recognize the identity the peer used in the previous
	AT_IDENTITY attribute. At most three EAP/AKA-Identity rounds can be		AT_IDENTITY attribute. At most three EAP/AKA-Identity rounds can be
	used. AT_ANY_ID_REQ can only be used in the first EAP-Request/AKA-		used, so the peer MUST NOT respond to more than three EAP-Request/
	Identity, in other words AT_ANY_ID_REQ MUST NOT be used in the		AKA-Identity messages within an EAP exchange. The peer MUST verify
	second or third EAP-Request/AKA-Identity. AT_FULLAUTH_ID_REQ MUST		that the sequence of EAP-Request/AKA-Identity packets the peer
	NOT be used if the previous EAP-Request/AKA-Identity included		receives comply with the sequencing rules defined in this document.
			That is, AT_ANY_ID_REQ can only be used in the first EAP-Request/
			AKA-Identity, in other words AT_ANY_ID_REQ MUST NOT be used in the
			second or third EAP-Request/AKA-Identity. AT_FULLAUTH_ID_REQ MUST NOT
			be used if the previous EAP-Request/AKA-Identity included
	AT_PERMANENT_ID_REQ. The peer operation in cases when it receives an		AT_PERMANENT_ID_REQ. The peer operation in cases when it receives an
	unexpected attribute is specified in Section 4.4.1.		unexpected attribute or an unexpected message is specified in Section
			4.4.1.
	Attacks against Identity Privacy		4.1.2.5 Attacks against Identity Privacy
	The section above specifies two possible ways the peer can operate		The section above specifies two possible ways the peer can operate
	upon receipt of AT_PERMANENT_ID_REQ. This is because a received		upon receipt of AT_PERMANENT_ID_REQ. This is because a received
	AT_PERMANENT_ID_REQ does not necessarily originate from the valid		AT_PERMANENT_ID_REQ does not necessarily originate from the valid
	network, but an active attacker may transmit an EAP-Request/AKA-		network, but an active attacker may transmit an EAP-Request/
	Identity packet with an AT_PERMANENT_ID_REQ attribute to the peer,		AKA-Identity packet with an AT_PERMANENT_ID_REQ attribute to the
	in an effort to find out the true identity of the user. If the peer		peer, in an effort to find out the true identity of the user. If the
	does not want to reveal its permanent identity, then the peer sends		peer does not want to reveal its permanent identity, then the peer
	the EAP-Response/AKA-Client-Error packet with the error code "unable		sends the EAP-Response/AKA-Client-Error packet with the error code
	to process packet", and the authentication exchange terminates.		"unable to process packet", and the authentication exchange
			terminates.
	Basically, there are two different policies that the peer can employ		Basically, there are two different policies that the peer can employ
	with regard to AT_PERMANENT_ID_REQ. A "conservative" peer assumes		with regard to AT_PERMANENT_ID_REQ. A "conservative" peer assumes
	that the network is able to maintain pseudonyms robustly. Therefore,		that the network is able to maintain pseudonyms robustly. Therefore,
	if a conservative peer has a pseudonym username, the peer responds		if a conservative peer has a pseudonym username, the peer responds
	with EAP-Response/AKA-Client-Error to the EAP packet with		with EAP-Response/AKA-Client-Error to the EAP packet with
	AT_PERMANENT_ID_REQ, because the peer believes that the valid		AT_PERMANENT_ID_REQ, because the peer believes that the valid network
	network is able to map the pseudonym identity to the peer's		is able to map the pseudonym identity to the peer's permanent
	permanent identity. (Alternatively, the conservative peer may accept		identity. (Alternatively, the conservative peer may accept
	AT_PERMANENT_ID_REQ in certain circumstances, for example if the		AT_PERMANENT_ID_REQ in certain circumstances, for example if the
	pseudonym was received a long time ago.) The benefit of this policy		pseudonym was received a long time ago.) The benefit of this policy
	is that it protects the peer against active attacks on anonymity. On		is that it protects the peer against active attacks on anonymity. On
	EAP AKA Authentication 27 October, 2003
	the other hand, a "liberal" peer always accepts the		the other hand, a "liberal" peer always accepts the
	AT_PERMANENT_ID_REQ and responds with the permanent identity. The		AT_PERMANENT_ID_REQ and responds with the permanent identity. The
	benefit of this policy is that it works even if the valid network		benefit of this policy is that it works even if the valid network
	sometimes loses pseudonyms and is not able to map them to the		sometimes loses pseudonyms and is not able to map them to the
	permanent identity.		permanent identity.
	Processing of AT_IDENTITY by the Server		4.1.2.6 Processing of AT_IDENTITY by the Server
	When the server receives an EAP-Response/AKA-Identity message with		When the server receives an EAP-Response/AKA-Identity message with
	the AT_IDENTITY (in response to the server's identity requesting		the AT_IDENTITY (in response to the server's identity requesting
	attribute), the server MUST operate as follows.		attribute), the server MUST operate as follows.
	If the server used AT_PERMANENT_ID_REQ, and if the AT_IDENTITY does		If the server used AT_PERMANENT_ID_REQ, and if the AT_IDENTITY does
	not contain a valid permanent identity, then the server sends EAP		not contain a valid permanent identity, then the server sends an
	Failure and the EAP exchange terminates. If the server recognizes		EAP-Request/AKA-Notification packet with AT_NOTIFICATION code 16384
	the permanent identity and is able to continue, then the server		to terminate the EAP exchange. If the server recognizes the permanent
	proceeds with full authentication by sending EAP-Request/AKA-		identity and is able to continue, then the server proceeds with full
	Challenge.		authentication by sending EAP-Request/AKA-Challenge.
	If the server used AT_FULLAUTH_ID_REQ, and if AT_IDENTITY contains a		If the server used AT_FULLAUTH_ID_REQ, and if AT_IDENTITY contains a
	valid permanent identity or a pseudonym identity that the server can		valid permanent identity or a pseudonym identity that the server can
	map to a valid permanent identity, then the server proceeds with		map to a valid permanent identity, then the server proceeds with full
	full authentication by sending EAP-Request/AKA-Challenge. If		authentication by sending EAP-Request/AKA-Challenge. If AT_IDENTITY
	AT_IDENTITY contains a pseudonym identity that the server is not		contains a pseudonym identity that the server is not able to map to a
	able to map to a valid permanent identity, or an identity that the		valid permanent identity, or an identity that the server is not able
	server is not able to recognize or classify, then the server sends		to recognize or classify, then the server sends EAP-Request/
	EAP-Request/ AKA-Identity with AT_PERMANENT_ID_REQ.		AKA-Identity with AT_PERMANENT_ID_REQ.
	If the server used AT_ANY_ID_REQ, and if the AT_IDENTITY contains a		If the server used AT_ANY_ID_REQ, and if the AT_IDENTITY contains a
	valid permanent identity or a pseudonym identity that the server can		valid permanent identity or a pseudonym identity that the server can
	map to a valid permanent identity, then the server proceeds with		map to a valid permanent identity, then the server proceeds with full
	full authentication by sending EAP-Request/ AKA-Challenge.		authentication by sending EAP-Request/ AKA-Challenge.
	If the server used AT_ANY_ID_REQ, and if AT_IDENTITY contains a		If the server used AT_ANY_ID_REQ, and if AT_IDENTITY contains a valid
	valid re-authentication identity and the server agrees on using re-		fast re-authentication identity and the server agrees on using re-
	authentication, then the server proceeds with re-authentication by		authentication, then the server proceeds with fast re-authentication
	sending EAP-Request/ AKA-Reauthentication (Section 4.2).		by sending EAP-Request/AKA-Reauthentication (Section 4.2).
	If the server used AT_ANY_ID_REQ, and if the peer sent an EAP-		If the server used AT_ANY_ID_REQ, and if the peer sent an
	Response/AKA-Identity with AT_IDENTITY that contains an identity		EAP-Response/AKA-Identity with AT_IDENTITY that contains an identity
	that the server recognizes as a re-authentication identity, but the		that the server recognizes as a fast re-authentication identity, but
	server is not able to map the identity to a permanent identity, then		the server is not able to map the identity to a permanent identity,
	the server sends EAP-Request/AKA-Identity with AT_FULLAUTH_ID_REQ.		then the server sends EAP-Request/AKA-Identity with
			AT_FULLAUTH_ID_REQ.
	If the server used AT_ANY_ID_REQ, and if AT_IDENTITY contains a		If the server used AT_ANY_ID_REQ, and if AT_IDENTITY contains a valid
	valid re-authentication identity, which the server is able to map to		fast re-authentication identity, which the server is able to map to a
	a permanent identity, and if the server does not want to use re-		permanent identity, and if the server does not want to use fast
	authentication, then the server proceeds with full authentication by		re-authentication, then the server proceeds with full authentication
	sending EAP-Request/AKA-Challenge.		by sending EAP-Request/AKA-Challenge.
	If the server used AT_ANY_ID_REQ, and AT_IDENTITY contains an		If the server used AT_ANY_ID_REQ, and AT_IDENTITY contains an
	identity that the server recognizes as a pseudonym identity but the		identity that the server recognizes as a pseudonym identity but the
	server is not able to map the pseudonym identity to a permanent		server is not able to map the pseudonym identity to a permanent
	EAP AKA Authentication 27 October, 2003
	identity, then the server sends EAP-Request/AKA-Identity with		identity, then the server sends EAP-Request/AKA-Identity with
	AT_PERMANENT_ID_REQ.		AT_PERMANENT_ID_REQ.
	If the server used AT_ANY_ID_REQ, and AT_IDENTITY contains an		If the server used AT_ANY_ID_REQ, and AT_IDENTITY contains an
	identity that the server is not able to recognize or classify, then		identity that the server is not able to recognize or classify, then
	the server sends EAP-Request/AKA-Identity with AT_FULLAUTH_ID_REQ.		the server sends EAP-Request/AKA-Identity with AT_FULLAUTH_ID_REQ.
	4.1.3. Message Sequence Examples (Informative)		4.1.3 Message Sequence Examples (Informative)
	This section contains non-normative message sequence examples to		This section contains non-normative message sequence examples to
	illustrate how the peer identity can be communicated to the server.		illustrate how the peer identity can be communicated to the server.
	sage of AT_ANY_ID_REQ		4.1.3.1 Usage of AT_ANY_ID_REQ
	Obtaining the peer identity with EAP/AKA attributes is illustrated		Obtaining the peer identity with EAP-AKA attributes is illustrated in
	in the figure below.		Figure 5 below.
	Peer Authenticator		Peer Authenticator
	| |		| |
	| +------------------------------+		| +------------------------------+
	| | Server does not have any |		| | Server does not have any |
	| | Subscriber identity available|		| | Subscriber identity available|
	| | When starting EAP/AKA |		| | When starting EAP-AKA |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_ANY_ID_REQ) |		| (AT_ANY_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY) |		| (AT_IDENTITY) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |		| |
	all Back on Full Authentication		Figure 5: Usage of AT_ANY_ID_REQ
	The figure below illustrates the case when the server does not		4.1.3.2 Fall Back on Full Authentication
	recognize the re-authentication identity the peer used in
	AT_IDENTITY.
	EAP AKA Authentication 27 October, 2003		Figure 6 illustrates the case when the server does not recognize the
			fast re-authentication identity the peer used in AT_IDENTITY.
	Peer Authenticator		Peer Authenticator
	| |		| |
	| +------------------------------+		| +------------------------------+
	| | Server does not have any |		| | Server does not have any |
	| | Subscriber identity available|		| | Subscriber identity available|
	| | When starting EAP/AKA |		| | When starting EAP-AKA |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_ANY_ID_REQ) |		| (AT_ANY_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY containing a re-authentication identity) |		| (AT_IDENTITY containing a fast re-auth. identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server does not recognize |		| | Server does not recognize |
	| | The re-authentication |		| | The fast re-auth. |
	| | Identity |		| | Identity |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_FULLAUTH_ID_REQ) |		| (AT_FULLAUTH_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY with a full-auth. Identity) |		| (AT_IDENTITY with a full-auth. Identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |		| |
	If the server recognizes the re-authentication identity, but still		Figure 6: Fall back on full authentication
	wants to fall back on full authentication, the server may issue the
	EAP-Request/AKA-Challenge packet. In this case, the full
	authentication procedure proceeds as usual.
	Requesting the Permanent Identity 1		If the server recognizes the fast re-authentication identity, but
			still wants to fall back on full authentication, the server may issue
			the EAP-Request/AKA-Challenge packet. In this case, the full
			authentication procedure proceeds as usual.
	The figure below illustrates the case when the EAP server fails to		4.1.3.3 Requesting the Permanent Identity 1
	decode a pseudonym identity included in the EAP-Response/Identity
	packet.
	EAP AKA Authentication 27 October, 2003		Figure 7 illustrates the case when the EAP server fails to decode a
			pseudonym identity included in the EAP-Response/Identity packet.
	Peer Authenticator		Peer Authenticator
	| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes a pseudonym) |		| (Includes a pseudonym) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server fails to decode the |		| | Server fails to decode the |
	| | Pseudonym. |		| | Pseudonym. |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_PERMANENT_ID_REQ) |		| (AT_PERMANENT_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY with permanent identity) |		| (AT_IDENTITY with permanent identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |		| |
	If the server recognizes the permanent identity, then the		Figure 7: Requesting the permanent identity 1
	authentication sequence proceeds as usual with the EAP Server
	issuing the EAP-Request/AKA-Challenge message.
	Requesting the Permanent Identity 2		If the server recognizes the permanent identity, then the
			authentication sequence proceeds as usual with the EAP Server issuing
			the EAP-Request/AKA-Challenge message.
	The figure below illustrates the case when the EAP server fails to		4.1.3.4 Requesting the Permanent Identity 2
	decode the pseudonym included in the AT_IDENTITY attribute.
	EAP AKA Authentication 27 October, 2003		Figure 8 illustrates the case when the EAP server fails to decode the
			pseudonym included in the AT_IDENTITY attribute.
	Peer Authenticator		Peer Authenticator
	| |		| |
	| +------------------------------+		| +------------------------------+
	| | Server does not have any |		| | Server does not have any |
	| | Subscriber identity available|		| | Subscriber identity available|
	| | When starting EAP/AKA |		| | When starting EAP-AKA |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_ANY_ID_REQ) |		| (AT_ANY_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| |
	|EAP-Response/AKA-Identity |		|EAP-Response/AKA-Identity |
	|(AT_IDENTITY with a pseudonym identity) |		|(AT_IDENTITY with a pseudonym identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| |
	| +------------------------------+		| +------------------------------+
	| | Server fails to decode the |		| | Server fails to decode the |
	| | Pseudonym in AT_IDENTITY |		| | Pseudonym in AT_IDENTITY |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_PERMANENT_ID_REQ) |		| (AT_PERMANENT_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY with permanent identity) |		| (AT_IDENTITY with permanent identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |		| |
	Three EAP/AKA-Identity Round Trips		Figure 8: Requesting the permanent identity 2
	The figure below illustrates the case with three EAP/AKA-Identity		4.1.3.5 Three EAP/AKA-Identity Round Trips
	round trips.
	EAP AKA Authentication 27 October, 2003		Figure 9 illustrates the case with three EAP/AKA-Identity round
			trips.
	Peer Authenticator		Peer Authenticator
	| |		| |
	| +------------------------------+		| +------------------------------+
	| | Server does not have any |		| | Server does not have any |
	| | Subscriber identity available|		| | Subscriber identity available|
	| | When starting EAP/AKA |		| | When starting EAP-AKA |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_ANY_ID_REQ) |		| (AT_ANY_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY with re-authentication identity) |		| (AT_IDENTITY with fast re-auth. identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server does not accept |		| | Server does not accept |
	| | The re-authentication |		| | The fast re-authentication |
	| | Identity |		| | Identity |
	| +------------------------------+		| +------------------------------+
	| |		| |
			: :
			: :
			: :
			: :
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_FULLAUTH_ID_REQ) |		| (AT_FULLAUTH_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	|EAP-Response/AKA-Identity |		|EAP-Response/AKA-Identity |
	|(AT_IDENTITY with a pseudonym identity) |		|(AT_IDENTITY with a pseudonym identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +------------------------------+		| +------------------------------+
	| | Server fails to decode the |		| | Server fails to decode the |
	| | Pseudonym in AT_IDENTITY |		| | Pseudonym in AT_IDENTITY |
	| +------------------------------+		| +------------------------------+
	| |
	| EAP-Request/AKA-Identity |		| EAP-Request/AKA-Identity |
	| (AT_PERMANENT_ID_REQ) |		| (AT_PERMANENT_ID_REQ) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| |
	| EAP-Response/AKA-Identity |		| EAP-Response/AKA-Identity |
	| (AT_IDENTITY with permanent identity) |		| (AT_IDENTITY with permanent identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |		| |
			Figure 9: Three EAP-AKA Start rounds
	After the last EAP-Response/AKA-Identity message, the full		After the last EAP-Response/AKA-Identity message, the full
	authentication sequence proceeds as usual.		authentication sequence proceeds as usual.
	4.2. Re-authentication		4.2 Fast Re-authentication
	4.2.1. General
	In some environments, EAP authentication may be performed
	frequently. Because the EAP AKA full authentication procedure makes
	EAP AKA Authentication 27 October, 2003		4.2.1 General
	use of the UMTS AKA algorithms, and it therefore requires fresh		In some environments, EAP authentication may be performed frequently.
	authentication vectors from the Authentication Centre, the full		Because the EAP-AKA full authentication procedure makes use of the
	authentication procedure may result in many network operations when		UMTS AKA algorithms, and it therefore requires fresh authentication
	used very frequently. Therefore, EAP AKA includes a more inexpensive		vectors from the Authentication Centre, the full authentication
			procedure may result in many network operations when used very
			frequently. Therefore, EAP-AKA includes a more inexpensive fast
	re-authentication procedure that does not make use of the UMTS AKA		re-authentication procedure that does not make use of the UMTS AKA
	algorithms and does not need new vectors from the Authentication		algorithms and does not need new vectors from the Authentication
	Centre.		Centre.
	Re-authentication is optional to implement for both the EAP AKA		Fast re-authentication is optional to implement for both the EAP-AKA
	server and peer. On each EAP authentication, either one of the		server and peer. On each EAP authentication, either one of the
	entities may also fall back on full authentication if they do not		entities may also fall back on full authentication if they do not
	want to use re-authentication.		want to use fast re-authentication.
	Re-authentication is based on the keys derived on the preceding full		Fast re-authentication is based on the keys derived on the preceding
	authentication. The same K_aut and K_encr keys as in full		full authentication. The same K_aut and K_encr keys as in full
	authentication are used to protect EAP AKA packets and attributes,		authentication are used to protect EAP-AKA packets and attributes,
	and the original Master Key from full authentication is used to		and the original Master Key from full authentication is used to
	generate a fresh Master Session Key, as specified in Section 4.5.		generate a fresh Master Session Key, as specified in Section 4.5.
	On re-authentication, the peer protects against replays with an		The fast re-authentication exchange makes use of an unsigned 16-bit
	unsigned 16-bit counter, included in the AT_COUNTER attribute. On		counter, included in the AT_COUNTER attribute. The counter has three
	full authentication, both the server and the peer initialize the		goals: 1) it can be used to limit the number of successive
	counter to one. The counter value of at least one is used on the		reauthentication exchanges without full-authentication 2) it
	first re-authentication. On subsequent re-authentications, the		contributes to the keying material, and 3) it protects the peer and
	counter MUST be greater than on any of the previous re-		the server from replays. On full authentication, both the server and
	authentications. For example, on the second re-authentication,		the peer initialize the counter to one. The counter value of at least
	counter value is two or greater etc. The AT_COUNTER attribute is		one is used on the first fast re-authentication. On subsequent fast
	encrypted.		re-authentications, the counter MUST be greater than on any of the
			previous fast re-authentications. For example, on the second fast
			re-authentication, counter value is two or greater etc. The
			AT_COUNTER attribute is encrypted.
	The server includes an encrypted server nonce (AT_NONCE_S) in the		Both the peer and the EAP server maintain a copy of the counter. The
	re-authentication request. The AT_MAC attribute in the peer's		EAP server sends its counter value to the peer in the fast
	response is calculated over NONCE_S to provide a challenge/response		re-authentication request. The peer MUST verify that its counter
	authentication scheme. The NONCE_S also contributes to the new		value is less than or equal to the value sent by the EAP server.
	Master Session Key.
			The server includes an encrypted server random nonce (AT_NONCE_S) in
			the fast re-authentication request. The AT_MAC attribute in the
			peer's response is calculated over NONCE_S to provide a challenge/
			response authentication scheme. The NONCE_S also contributes to the
			new Master Session Key.
	Both the peer and the server SHOULD have an upper limit for the		Both the peer and the server SHOULD have an upper limit for the
	number of subsequent re-authentications allowed before a full		number of subsequent fast re-authentications allowed before a full
	authentication needs to be performed. Because a 16-bit counter is		authentication needs to be performed. Because a 16-bit counter is
	used in re-authentication, the theoretical maximum number of re-		used in fast re-authentication, the theoretical maximum number of re-
	authentications is reached when the counter value reaches 0xFFFF.		authentications is reached when the counter value reaches FFFF
	In order to use re-authentication, the peer and the EAP server need		hexadecimal. In order to use fast re-authentication, the peer and the
	to store the following values: Master Key, latest counter value and		EAP server need to store the following values: Master Key, latest
	the next re-authentication identity. K_aut, K_encr may either be		counter value and the next fast re-authentication identity. K_aut,
	stored or derived again from MK. The server may also need to store		K_encr may either be stored or derived again from MK. The server may
	the permanent identity of the user.		also need to store the permanent identity of the user.
	4.2.2. Re-authentication Identity		4.2.2 Comparison to UMTS AKA
	The re-authentication procedure makes use of separate re-		When analyzing the fast re-authentication exchange, it may be helpful
	authentication user identities. Pseudonyms and the permanent		to compare it with the UMTS Authentication and Key Agreement (AKA)
	identity are reserved for full authentication only. If a re-		exchange, which it resembles closely. The counter corresponds to the
	authentication identity is lost and the network does not recognize		UMTS AKA sequence number, NONCE_S corresponds to RAND, and AT_MAC in
	it, the EAP server can fall back on full authentication.		EAP-Request/AKA-Reauthentication corresponds to AUTN, the AT_MAC in
			EAP-Response/AKA-Reauthentication corresponds to RES,
			AT_COUNTER_TOO_SMALL corresponds to AUTS, and encrypting the counter
			corresponds to the usage of the Anonymity Key. Also the key
			generation on fast re-authentication with regard to random or fresh
			material is similar to UMTS AKA -- the server generates the NONCE_S
			and counter values, and the peer only verifies that the counter value
			is fresh.
	EAP AKA Authentication 27 October, 2003		It should also be noted that encrypting the AT_NONCE_S, AT_COUNTER or
			AT_COUNTER_TOO_SMALL attributes is not important to the security of
			the fast re-authentication exchange.
	If the EAP server supports re-authentication, it MAY include the		4.2.3 Fast Re-authentication Identity
	skippable AT_NEXT_REAUTH_ID attribute in the encrypted data of EAP-
	Request/AKA-Challenge message. This attribute contains a new re-
	authentication identity for the next re-authentication. The peer MAY
	ignore this attribute, in which case it will use full authentication
	next time. If the peer wants to use re-authentication, it uses this
	re-authentication identity on next authentication. Even if the peer
	has a re-authentication identity, the peer MAY discard the re-
	authentication identity and use a pseudonym or the permanent
	identity instead, in which case full authentication MUST be
	performed.
	In environments where a real portion is needed in the peer identity,		The fast re-authentication procedure makes use of separate re-
	the re-authentication identity received in AT_NEXT_REAUTH_ID MUST		authentication user identities. Pseudonyms and the permanent identity
	contain both a username portion and a realm portion, as per the NAI		are reserved for full authentication only. If a fast
	format. The EAP Server can choose an appropriate realm part in order		re-authentication identity is lost and the network does not recognize
	to have the AAA infrastructure route subsequent re-authentication		it, the EAP server can fall back on full authentication. If the EAP
	related requests to the same AAA server. For example, the realm part		server supports fast re-authentication, it MAY include the skippable
	MAY include a portion that is specific to the AAA server. Hence, it		AT_NEXT_REAUTH_ID attribute in the encrypted data of EAP- Request/
	is sufficient to store the context required for re-authentication in		AKA-Challenge message. This attribute contains a new re-
	the AAA server that performed the full authentication.		authentication identity for the next fast re-authentication. The
			attribute also works as a capability flag that indicates the fact
			that the server supports fast re-authentication, and that the server
			wants to continue using fast re-authentication within the current
			context. The peer MAY ignore this attribute, in which case it will
			use full authentication next time. If the peer wants to use fast
			re-authentication, it uses this fast re-authentication identity on
			next authentication. Even if the peer has a fast re-authentication
			identity, the peer MAY discard the re- authentication identity and
			use a pseudonym or the permanent identity instead, in which case full
			authentication MUST be performed. If the EAP server does not include
			the AT_NEXT_REAUTH_ID in the encrypted data of EAP-Request/
			AKA-Challenge or EAP-Request/AKA-Reauthentication, then the peer MUST
			discard its current fast re-authentication state information and
			perform a full authentication next time.
	The peer MAY use the re-authentication identity in the EAP-		In environments where a realm portion is needed in the peer identity,
	Response/Identity packet or, in response to server's AT_ANY_ID_REQ		the fast re-authentication identity received in AT_NEXT_REAUTH_ID
	attribute, the peer MAY use the re-authentication identity in the		MUST contain both a username portion and a realm portion, as per the
	AT_IDENTITY attribute of the EAP-Response/AKA-Identity packet. The		NAI format. The EAP Server can choose an appropriate realm part in
	peer MUST NOT modify the username portion of the re-authentication		order to have the AAA infrastructure route subsequent fast
	identity, but the peer MAY modify the realm portion or replace it		re-authentication related requests to the same AAA server. For
	with another realm portion.		example, the realm part MAY include a portion that is specific to the
			AAA server. Hence, it is sufficient to store the context required for
			fast re-authentication in the AAA server that performed the full
			authentication.
	Even if the peer uses a re-authentication identity, the server may		The peer MAY use the fast re-authentication identity in the
	want to fall back on full authentication, for example because the		EAP-Response/Identity packet or, in response to server's
	server does not recognize the re-authentication identity or does not		AT_ANY_ID_REQ attribute, the peer MAY use the fast re-authentication
	want to use re-authentication. If the server was able to decode the		identity in the AT_IDENTITY attribute of the EAP-Response/
	re-authentication identity to the permanent identity, the server		AKA-Identity packet. The peer MUST NOT modify the username portion of
	issues the EAP-Request/AKA-Challenge packet to initiate full		the fast re-authentication identity, but the peer MAY modify the
	authentication. If the server was not able to recover the peer's		realm portion or replace it with another realm portion.
	identity from the re-authentication identity, the server starts the
	full authentication procedure by issuing an EAP-Request/AKA-Identity
	packet. This packet always starts a full authentication sequence if
	it does not include the AT_ANY_ID_REQ attribute.
	4.2.3. Re-authentication Procedure		Even if the peer uses a fast re-authentication identity, the server
			may want to fall back on full authentication, for example because the
			server does not recognize the fast re-authentication identity or does
			not want to use fast re-authentication. If the server was able to
			decode the fast re-authentication identity to the permanent identity,
			the server issues the EAP-Request/AKA-Challenge packet to initiate
			full authentication. If the server was not able to recover the peer's
			identity from the fast re-authentication identity, the server starts
			the full authentication procedure by issuing an EAP-Request/
			AKA-Identity packet. This packet always starts a full authentication
			sequence if it does not include the AT_ANY_ID_REQ attribute.
	The following figure illustrates the re-authentication procedure.		4.2.4 Fast Re-authentication Procedure
	Encrypted attributes are denoted with '*'. The peer uses its re-
	authentication identity in the EAP-Response/Identity packet. As		Figure 10 illustrates the fast re-authentication procedure. In this
	discussed above, an alternative way to communicate the re-		example, the optional protected success indication is not used.
	authentication identity to the server is for the peer to use the		Encrypted attributes are denoted with '*'. The peer uses its fast
			re-authentication identity in the EAP-Response/Identity packet. As
			discussed above, an alternative way to communicate the fast
			re-authentication identity to the server is for the peer to use the
	AT_IDENTITY attribute in the EAP-Response/AKA-Identity message. This		AT_IDENTITY attribute in the EAP-Response/AKA-Identity message. This
	latter case is not illustrated in the figure below, and it is only		latter case is not illustrated in the figure below, and it is only
	possible when the server requests the peer to send its identity by		possible when the server requests the peer to send its identity by
	including the AT_ANY_ID_REQ attribute in the EAP-Request/AKA-		including the AT_ANY_ID_REQ attribute in the EAP-Request/AKA-Identity
	Identity packet.		packet.
	EAP AKA Authentication 27 October, 2003
	If the server recognizes the re-authentication identity and agrees		If the server recognizes the identity as a valid fast
	on using re-authentication, then the server sends the EAP-		re-authentication identity, and if the server agrees on using fast
	Request/AKA-Reauthentication packet to the peer. This packet MUST		re-authentication, then the server sends the EAP- Request/
	include the encrypted AT_COUNTER attribute, with a fresh counter		AKA-Reauthentication packet to the peer. This packet MUST include the
	value, the encrypted AT_NONCE_S attribute that contains a random		encrypted AT_COUNTER attribute, with a fresh counter value, the
	number chosen by the server, the AT_ENCR_DATA and the AT_IV		encrypted AT_NONCE_S attribute that contains a random number chosen
	attributes used for encryption, and the AT_MAC attribute that		by the server, the AT_ENCR_DATA and the AT_IV attributes used for
	contains a message authentication code over the packet. The packet		encryption, and the AT_MAC attribute that contains a message
	MAY also include an encrypted AT_NEXT_REAUTH_ID attribute that		authentication code over the packet. The packet MAY also include an
	contains the next re-authentication identity.		encrypted AT_NEXT_REAUTH_ID attribute that contains the next fast
			re-authentication identity.
	Re-authentication identities are one-time identities. If the peer		Fast re-authentication identities are one-time identities. If the
	does not receive a new re-authentication identity, it MUST use		peer does not receive a new fast re-authentication identity, it MUST
	either the permanent identity or a pseudonym identity on the next		use either the permanent identity or a pseudonym identity on the next
	authentication to initiate full authentication.		authentication to initiate full authentication.
	The peer verifies that the counter value is fresh (greater than any		The peer verifies that AT_MAC is correct and that the counter value
	previously used value). The peer also verifies that AT_MAC is		is fresh (greater than any previously used value). The peer MAY save
	correct. The peer MAY save the next re-authentication identity from		the next fast re-authentication identity from the encrypted
	the encrypted AT_NEXT_REAUTH_ID for next time. If all checks are		AT_NEXT_REAUTH_ID for next time. If all checks are successful, the
	successful, the peer responds with the EAP-Response/AKA-		peer responds with the EAP-Response/AKA-Reauthentication packet,
	Reauthentication packet, including the AT_COUNTER attribute with the		including the AT_COUNTER attribute with the same counter value and
	same counter value and the AT_MAC attribute.		the AT_MAC attribute.
	The server verifies the AT_MAC attribute and also verifies that the		The server verifies the AT_MAC attribute and also verifies that the
	counter value is the same that it used in the EAP-Request/AKA-		counter value is the same that it used in the EAP-Request/AKA-
	Reauthentication packet. If these checks are successful, the re-		Reauthentication packet. If these checks are successful, the fast
	authentication has succeeded and the server sends the EAP-Success		re-authentication has succeeded and the server sends the EAP-Success
	packet to the peer.		packet to the peer.
	EAP AKA Authentication 27 October, 2003		If protected success indications (Section 4.3.2) were used, the
			EAP-Success packet would be preceded by an EAP-SIM notification
			round.
	Peer Authenticator		Peer Authenticator
	| |		| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes a re-authentication identity) |		| (Includes a fast re-authentication identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +--------------------------------+		| +--------------------------------+
	| | Server recognizes the identity |		| | Server recognizes the identity |
	| | and agrees on using fast |		| | and agrees on using fast |
	| | re-authentication |		| | re-authentication |
	| +--------------------------------+		| +--------------------------------+
	| |
	| EAP-Request/AKA-Reauthentication |		| EAP-Request/AKA-Reauthentication |
	| (AT_IV, AT_ENCR_DATA, *AT_COUNTER, |		| (AT_IV, AT_ENCR_DATA, *AT_COUNTER, |
	| *AT_NONCE_S, *AT_NEXT_REAUTH_ID, AT_MAC) |		| *AT_NONCE_S, *AT_NEXT_REAUTH_ID, AT_MAC) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
			: :
			: :
			: :
			: :
	| |		| |
	+-----------------------------------------------+ |		+-----------------------------------------------+ |
	| Peer verifies AT_MAC and the freshness of | |		| Peer verifies AT_MAC and the freshness of | |
	| the counter. Peer MAY store the new re- | |		| the counter. Peer MAY store the new re- | |
	| authentication identity for next re-auth. | |		| authentication identity for next re-auth. | |
	+-----------------------------------------------+ |		+-----------------------------------------------+ |
	| |		| |
	| EAP-Response/AKA-Reauthentication |		| EAP-Response/AKA-Reauthentication |
	| (AT_IV, AT_ENCR_DATA, *AT_COUNTER with same value, |		| (AT_IV, AT_ENCR_DATA, *AT_COUNTER with same value, |
	| AT_MAC) |		| AT_MAC) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +--------------------------------+		| +--------------------------------+
	| | Server verifies AT_MAC and |		| | Server verifies AT_MAC and |
	| | the counter |		| | the counter |
	| +--------------------------------+		| +--------------------------------+
	| |
	| EAP-Success |		| EAP-Success |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |		| |
	4.2.4. Re-authentication Procedure when Counter is Too Small		Figure 10: Reauthentication
	If the peer does not accept the counter value of EAP-Request/AKA-		4.2.5 Fast Re-authentication Procedure when Counter is Too Small
	Reauthentication, it indicates the counter synchronization problem
	by including the encrypted AT_COUNTER_TOO_SMALL in EAP-Response/AKA-
	Reauthentication. The server responds with EAP-Request/AKA-Challenge
	to initiate a normal full authentication procedure. This is
	illustrated in the following figure. Encrypted attributes are
	denoted with '*'.
	EAP AKA Authentication 27 October, 2003		If the peer does not accept the counter value of EAP-Request/
			AKA-Reauthentication, it indicates the counter synchronization
			problem by including the encrypted AT_COUNTER_TOO_SMALL in
			EAP-Response/AKA-Reauthentication. The server responds with
			EAP-Request/AKA-Challenge to initiate a normal full authentication
			procedure. This is illustrated in Figure 11. Encrypted attributes are
			denoted with '*'.
	Peer Authenticator		Peer Authenticator
	| |
	| EAP-Request/Identity |		| EAP-Request/Identity |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	| EAP-Response/Identity |		| EAP-Response/Identity |
	| (Includes a re-authentication identity) |		| (Includes a fast re-authentication identity) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |		| |
	| EAP-Request/AKA-Reauthentication |		| EAP-Request/AKA-Reauthentication |
	| (AT_IV, AT_ENCR_DATA, *AT_COUNTER, |		| (AT_IV, AT_ENCR_DATA, *AT_COUNTER, |
	| *AT_NONCE_S, *AT_NEXT_REAUTH_ID, AT_MAC) |		| *AT_NONCE_S, *AT_NEXT_REAUTH_ID, AT_MAC) |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	+-----------------------------------------------+ |		+-----------------------------------------------+ |
	| AT_MAC is valid but the counter is not fresh. | |		| AT_MAC is valid but the counter is not fresh. | |
	+-----------------------------------------------+ |		+-----------------------------------------------+ |
	| |
	| EAP-Response/AKA-Reauthentication |		| EAP-Response/AKA-Reauthentication |
	| (AT_IV, AT_ENCR_DATA, *AT_COUNTER_TOO_SMALL, |		| (AT_IV, AT_ENCR_DATA, *AT_COUNTER_TOO_SMALL, |
	| *AT_COUNTER, AT_MAC) |		| *AT_COUNTER, AT_MAC) |
	|------------------------------------------------------>|		|------------------------------------------------------>|
	| |
	| +----------------------------------------------+		| +----------------------------------------------+
	| | Server verifies AT_MAC but detects |		| | Server verifies AT_MAC but detects |
	| | That peer has included AT_COUNTER_TOO_SMALL|		| | That peer has included AT_COUNTER_TOO_SMALL|
	| +----------------------------------------------+		| +----------------------------------------------+
	| |
	| EAP-Request/AKA-Challenge |		| EAP-Request/AKA-Challenge |
	|<------------------------------------------------------|		|<------------------------------------------------------|
	| |
	+---------------------------------------------------------------+		+---------------------------------------------------------------+
	| Normal full authentication follows. |		| Normal full authentication follows. |
	+---------------------------------------------------------------+		+---------------------------------------------------------------+
	| |		| |
			Figure 11: Fast re-authentication counter too small
	In the figure above, the first three messages are similar to the		In the figure above, the first three messages are similar to the
	basic re-authentication case. When the peer detects that the counter		basic fast re-authentication case. When the peer detects that the
	value is not fresh, it includes the AT_COUNTER_TOO_SMALL attribute		counter value is not fresh, it includes the AT_COUNTER_TOO_SMALL
	in EAP-Response/AKA-Reauthentication. This attribute doesn't contain		attribute in EAP-Response/AKA-Reauthentication. This attribute
	any data but it is a request for the server to initiate full		doesn't contain any data but it is a request for the server to
	authentication. In this case, the peer MUST ignore the contents of		initiate full authentication. In this case, the peer MUST ignore the
	the server's AT_NEXT_REAUTH_ID attribute.		contents of the server's AT_NEXT_REAUTH_ID attribute.
	On receipt of AT_COUNTER_TOO_SMALL, the server verifies AT_MAC and		On receipt of AT_COUNTER_TOO_SMALL, the server verifies AT_MAC and
	verifies that AT_COUNTER contains the same as in the EAP-		verifies that AT_COUNTER contains the same counter value as in the
	Request/AKA-Reauthentication packet. If not, the server silently		EAP-Request/AKA-Reauthentication packet. If not, the server
	discards the EAP-Response/AKA-Reauthentication packet. If all checks		terminates the authentication exchange by sending the EAP-Request/
	on the packet are successful, the server transmits a EAP-		AKA-Notification packet with AT_NOTIFICATION code 16384. If all
	Request/AKA-Challenge packet and the full authentication procedure		checks on the packet are successful, the server transmits a
	is performed as usual. Since the server already knows the subscriber		EAP-Request/AKA-Challenge packet and the full authentication
	identity, it MUST NOT use the EAP-Request/AKA-Identity packet to		procedure is performed as usual. Since the server already knows the
	request the identity.		subscriber identity, it MUST NOT use the EAP-Request/AKA-Identity
			packet to request the identity.
	EAP AKA Authentication 27 October, 2003		4.3 EAP-AKA Notifications
	4.3. EAP/AKA Notifications		4.3.1 General
	The EAP-Request/Notification, specified in [EAP], can be used to		The EAP server can use EAP-AKA notifications to convey localizable
	convey a displayable message from the EAP server to the peer.		notifications and result indications (Section 4.3.2) to the peer.
	Because these messages are textual messages, it may be hard for the
	peer to present them in the user's preferred language. Therefore,
	EAP/AKA uses a separate EAP/AKA message subtype to transmit
	localizable notification codes instead of the EAP-
	Request/Notification packet.
	The EAP server MAY issue an EAP-Request/AKA-Notification packet to		The server MUST use notifications in cases discussed in Section
	the peer. The peer MAY show a notification message to the user and		4.4.2. When the EAP server issues an EAP-Request/AKA-Notification
	the peer MUST respond to the EAP server with an EAP-Response/AKA-		packet to the peer, the peer MUST process the notification packet.The
	Notification packet, even if the peer did not recognize the		peer MAY show a notification message to the user and the peer MUST
	notification code.		respond to the EAP server with an EAP-Response/AKA-Notification
			packet, even if the peer did not recognize the notification code.
	The notification code is a 16-bit number. The most significant bit		An EAP-AKA full authentication exchange or a fast re-authentication
	is called the Failure bit (F bit). The F bit specifies whether the		exchange MUST NOT include more than one EAP-AKA notification round.
			The notification code is a 16-bit number. The most significant bit is
			called the Failure bit (F bit). The F bit specifies whether the
	notification implies failure. The code values with the F bit set to		notification implies failure. The code values with the F bit set to
	zero (code values 0...32767) are used on unsuccessful cases. The		zero (code values 0...32767) are used on unsuccessful cases. The
	receipt of a notification code from this range implies failed		receipt of a notification code from this range implies failed EAP
	authentication, so the peer can use the notification as a failure		exchange, so the peer can use the notification as a failure
	indication. After receiving the EAP-Response/AKA-Notification for		indication. After receiving the EAP-Response/AKA-Notification for
	these notification codes, the server MUST send the EAP-Failure		these notification codes, the server MUST send the EAP-Failure
	packet.		packet.
	The receipt of a notification code with the F bit set to one (values		The receipt of a notification code with the F bit set to one (values
	32768...65536) does not imply failure, so the peer MUST NOT change		32768...65536) does not imply failure. Notification code 32768 has
	its state when it receives such a notification. (This version of the		been reserved as a general notification code to indicate successful
	protocol does not specify any notification codes with the F bit set		authentication.
	to one.)
	The second most significant bit of the notification code is called		The second most significant bit of the notification code is called
	the Phase bit (P bit). It specifies at which phase of the EAP/AKA		the Phase bit (P bit). It specifies at which phase of the EAP-AKA
	exchange the notification can be used. If the P bit is set to zero,		exchange the notification can be used. If the P bit is set to zero,
	the notification can only be used after the EAP/AKA-Challenge round		the notification can only be used after a successful EAP/
	in full authentication or the EAP/AKA-Reauthentication round in		AKA-Challenge round in full authentication or a successful EAP/
	reautentication. For these notifications, the AT_MAC attribute MUST		AKA-Reauthentication round in reautentication. A re-authentication
	be included in both EAP-Request/AKA-Notification and EAP-		round is considered successful only if the peer has successfully
	Response/AKA-Notification.		verified AT_MAC and AT_COUNTER attributes, and does not include the
			AT_COUNTER_TOO_SMALL attribute in EAP-Response/AKA-Reauthentication.
	If the P bit is set to one, the notification can only by used before		If the P bit is set to one, the notification can only by used before
	the EAP/AKA-Challenge round in full authentication or the EAP/AKA-		the EAP/AKA-Challenge round in full authentication or before the EAP/
	Reauthentication round in reauthentication. For these notifications,		AKA-Reauthentication round in reauthentication.
	the AT_MAC attribute MUST NOT be included in either EAP-Request/AKA-
	Notification or EAP-Response/AKA-Notification. (This version of the		Section 6.10 and Section 6.11 specify what other attributes must be
	protocol does not specify any notification codes with the P bit set		included in the notification packets.
	to one.)
	Some of the notification codes are authorization related and hence		Some of the notification codes are authorization related and hence
	not usually considered as part of the responsibility of an EAP		not usually considered as part of the responsibility of an EAP
	method. However, they are included as part of EAP/AKA because there		method. However, they are included as part of EAP-AKA because there
	are currently no other ways to convey this information to the user		are currently no other ways to convey this information to the user in
			a localizable way, and the information is potentially useful for the
			user. An EAP-AKA server implementation may decide never to send these
			EAP-AKA notifications.
	EAP AKA Authentication 27 October, 2003		4.3.2 Result Indications
	in a localizable way, and the information is potentially useful for		As discussed in Section 4.4, the server and the peer use explicit
	the user. An EAP/AKA server implementation may decide never to send		error messages in all error cases. If the server detects an error
	these EAP/AKA notifications.		after successful authentication, the server uses an EAP-AKA
			notification to indicate failure to the peer. In this case, the
			result indication is integrity and replay protected.
	4.4. Error Cases		By sending an EAP-Response/AKA-Challenge packet or an EAP-Response/
			AKA-Reauthentication packet (without AT_COUNTER_TOO_SMALL), the peer
			indicates that it has successfully authenticated the server and that
			the peer's local policy accepts the EAP exchange. In other words,
			these packets are implicit success indications from the peer to the
			server.
			EAP-AKA also supports optional protected success indications from the
			server to the peer. If the EAP server wants to use protected success
			indications, it includes the AT_RESULT_IND attribute in the
			EAP-Request/AKA-Challenge or the EAP-Request/AKA-Reauthentication
			packet. This attribute indicates, that the EAP server would like to
			use result indications in both successful and unsuccessful cases. If
			the peer also wants this, the peer includes AT_RESULT_IND in
			EAP-Response/AKA-Challenge or EAP-Response/AKA-Re-authentication. The
			peer MUST NOT include AT_RESULT_IND if it did not receive
			AT_RESULT_IND from the server. If both the peer and the server used
			AT_RESULT_IND, then the EAP exchange is not complete yet, but an
			EAP-AKA notification round will follow. The following EAP-SIM
			notification may indicate either failure or success.
			Success indications with the AT_NOTIFICATION code 32768 can only be
			used if both the server and the peer indicate they want to use them
			with AT_RESULT_IND. If the server did not include AT_RESULT_IND in
			the EAP-Request/AKA-Challenge or EAP-Request/AKA-Reauthentication
			packet, or if the peer did not include AT_RESULT_IND in the
			corresponding response packet, then the server MUST NOT use protected
			success indications.
			Because the AT_NOTIFICATION code 32768 is used to indicate success,
			the server MUST ignore the contents of the EAP-AKA response it
			receives to the EAP-Request/AKA-Notification with this code.
			Regardless of the contents of the EAP-AKA response, the server MUST
			send EAP-Success as the next packet.
			4.4 Error Cases
	This section specifies the operation of the peer and the server in		This section specifies the operation of the peer and the server in
	error cases. The subsections below require the EAP/AKA peer and		error cases. The subsections below require the EAP-AKA peer and
	server to send an error packet (EAP-Response/AKA-Client-Error or EAP		server to send an error packet (EAP-Response/AKA-Client-Error or
	Failure) in error cases. However, implementations SHOULD NOT rely		EAP-Request/AKA-Notification) in error cases. However,
	upon the correct error reporting behavior of the peer,		implementations SHOULD NOT rely upon the correct error reporting
	authenticator, or the server. It is possible for error and other		behavior of the peer, authenticator, or the server. It is possible
	messages to be lost in transit or for a malicious participant to		for error and other messages to be lost in transit or for a malicious
	attempt to consume resources by not issuing error messages. Both		participant to attempt to consume resources by not issuing error
	the peer and the EAP server SHOULD have a mechanism to clean up		messages. Both the peer and the EAP server SHOULD have a mechanism
	state even if an error message or EAP Success is not received after		to clean up state even if an error message or EAP-Success is not
	a timeout period.		received after a timeout period.
	4.4.1. Peer Operation		4.4.1 Peer Operation
	Two special error messages have been specified for error cases that		Two special error messages have been specified for error cases that
	are related to the processing of the UMTS AKA AUTN parameter, as		are related to the processing of the UMTS AKA AUTN parameter, as
	described in Section 3: (1) if the peer does not accept AUTN, the		described in Section 3: (1) if the peer does not accept AUTN, the
	peer responds with EAP-Response/AKA-Authentication-Reject (Section		peer responds with EAP-Response/AKA-Authentication-Reject (Section
	6.5), and the server issues EAP Failure, and (2) if the peer detects		6.5), and the server issues EAP-Failure, and (2) if the peer detects
	that the sequence number in AUTN is not correct, the peer responds		that the sequence number in AUTN is not correct, the peer responds
	with EAP-Response/AKA-Synchronization-Failure (Section 6.6), and the		with EAP-Response/AKA-Synchronization-Failure (Section 6.6), and the
	server proceeds with a new EAP-Request/AKA-Challenge.		server proceeds with a new EAP-Request/AKA-Challenge.
	In other error cases, when an EAP/AKA peer detects an error in a		In other error cases, when an EAP-AKA peer detects an error in a
	received EAP/AKA packet, the EAP/AKA peer responds with the EAP-		received EAP-AKA packet, the EAP-AKA peer responds with the
	Response/AKA-Client-Error packet. In response to the EAP-		EAP-Response/AKA-Client-Error packet. In response to the
	Response/AKA-Client-Error, the EAP server MUST issue the EAP Failure		EAP-Response/AKA-Client-Error, the EAP server MUST issue the
	packet and the authentication exchange terminates.		EAP-Failure packet and the authentication exchange terminates.
	By default, the peer uses the client error code 0, "unable to
	process packet". This error code is used in the following cases:
	- the peer is not able to parse the EAP request, i.e. the EAP
	request is malformed
	- the peer encountered a malformed attribute
	- wrong attribute types or duplicate attributes have been included
	in the EAP request
	- a mandatory attribute is missing
	- unrecognized non-skippable attribute
	- unrecognized or unexpected EAP/AKA Subtype in the EAP request
	- invalid AT_MAC
	EAP AKA Authentication 27 October, 2003
	- invalid AT_CHECKCODE		By default, the peer uses the client error code 0, "unable to process
			packet". This error code is used in the following cases:
	- invalid pad bytes in AT_PADDING		o EAP exchange is not acceptable according to the peer's local
			policy.
			o the peer is not able to parse the EAP request, i.e. the EAP
			request is malformed
			o the peer encountered a malformed attribute
			o wrong attribute types or duplicate attributes have been included
			in the EAP request
	- the peer does not want to process AT_PERMANENT_ID_REQ		o a mandatory attribute is missing
			o unrecognized non-skippable attribute
			o unrecognized or unexpected EAP-AKA Subtype in the EAP request
			o invalid AT_MAC
			o invalid AT_CHECKCODE
			o invalid pad bytes in AT_PADDING
			o the peer does not want to process AT_PERMANENT_ID_REQ
	4.4.2. Server Operation		4.4.2 Server Operation
	If an EAP/AKA server detects an error in a received EAP/AKA		If an EAP-AKA server detects an error in a received EAP-AKA response,
	response, the server MUST issue the EAP Failure packet and the		the server MUST issue the EAP-Request/AKA-Notification packet with an
	authentication exchange terminates. The errors cases when the server		AT_NOTIFICATION code that implies failure. By default, the server
	issues an EAP Failure include the following:		uses one of the general failure codes (0 or 16384). The choice
			between these two codes depends on the phase of the EAP-AKA exchange,
			see Section 4.3. The errors cases when the server issues an
			EAP-Request/AKA-Notification that implies failure include the
			following:
	- the server is not able to parse the peer's EAP response		o the server is not able to parse the peer's EAP response
			o the server encounters a malformed attribute, a non-recognized non-
			skippable attribute, or a duplicate attribute
			o a mandatory attribute is missing or an invalid attribute was
			included
			o unrecognized or unexpected EAP-AKA Subtype in the EAP Response
			o invalid AT_MAC
			o invalid AT_CHECKCODE
			o invalid AT_COUNTER
	- the server encounters a malformed attribute, a non-recognized non-		4.4.3 EAP-Failure
	skippable attribute, or a duplicate attribute
	- a mandatory attribute is missing or an invalid attribute was		The EAP-AKA server sends EAP-Failure in three cases:
	included
	- unrecognized or unexpected EAP/AKA Subtype in the EAP Response		1) In response to an EAP-Response/AKA-Client-Error packet the server
			has received from the peer, or
	- invalid AT_MAC		2) In response to an EAP-Response/AKA-Authentication-Reject packet
			the server has received from the peer, or
	- invalid AT_CHECKCODE		3) Following an EAP-AKA notification round, when the AT_NOTIFICATION
			code implies failure.
	- invalid AT_COUNTER		The EAP-AKA server MUST NOT send EAP-Failure in other cases than
			these three. However, it should be noted that even though the EAP-AKA
			server would not send an EAP-Failure, an authorization decision that
			happens outside EAP-AKA, such as in the AAA server or in an
			intermediate AAA proxy, may result in a failed exchange.
	4.4.3. Failure		The peer MUST accept the EAP-Failure packet in case 1), case 2) and
			case 3) above. The peer SHOULD silently discard the EAP-Failure
			packet in other cases.
	As normally in EAP, the EAP server sends the EAP-Failure packet to		4.4.4 EAP-Success
	the peer when the authentication procedure fails on the EAP Server.
	In EAP/AKA, this may occur for example if the EAP server does not
	recognize the peer identity, or if the EAP server is not able to
	obtain the authentication vectors for the subscriber or the
	authentication exchange times out. The server may also send EAP
	Failure if there is an error in the received EAP/AKA response, as
	discussed in Section 4.4.2.
	The server can send EAP-Failure at any time in the EAP exchange. The		On full authentication, the server can only send EAP-Success after
	peer MUST process EAP-Failure.		the EAP/AKA-Challenge round. The peer MUST silently discard any
			EAP-Success packets if they are received before the peer has
			successfully authenticated the server and sent the EAP-Response/
			AKA-Challenge packet.
	4.4.4. EAP Success		If the peer did not indicate that it wants to use protected success
			indications with AT_RESULT_IND (as discussed in Section 4.3.2) on
			full authentication, then the peer MUST accept EAP-Success after a
			successful EAP/AKA-Challenge round.
	On full authentication, the server can only send EAP-Success after		If the peer indicated that it wants to use protected success
	the EAP/AKA-Challenge round. The peer MUST silently discard any EAP-		indications with AT_RESULT_IND (as discussed in Section 4.3.2), then
	Success packets if they are received before the peer has		the peer MUST NOT accept EAP-Success after a successful EAP/
	successfully authenticated the server and sent the EAP-Response/AKA-		AKA-Challenge round. In this case, the peer MUST only accept
	Challenge packet.		EAP-Success after receiving an EAP-AKA Notification with the
			AT_NOTIFICATION code 32768.
	On re-authentication, EAP-Success can only be sent after the		On fast re-authentication, EAP-Success can only be sent after the
	EAP/AKA-Reauthentication round. The peer MUST silently discard any		EAP/AKA-Reauthentication round. The peer MUST silently discard any
	EAP-Success packets if they are received before the peer has		EAP-Success packets if they are received before the peer has
			successfully authenticated the server and sent the EAP-Response/
			AKA-Reauthentication packet.
	EAP AKA Authentication 27 October, 2003		If the peer did not indicate that it wants to use protected success
			indications with AT_RESULT_IND (as discussed in Section 4.3.2) on
			fast re-authentication, then the peer MUST accept EAP-Success after a
			successful EAP/AKA-Reauthentication round.
	successfully authenticated the server and sent the EAP-Response/AKA-		If the peer indicated that it wants to use protected success
	Reauthentication packet.		indications with AT_RESULT_IND (as discussed in Section 4.3.2), then
			the peer MUST NOT accept EAP-Success after a successful EAP/
			AKA-Reauthentication round. In this case, the peer MUST only accept
			EAP-Success after receiving an EAP-AKA Notification with the
			AT_NOTIFICATION code 32768.
	If the peer receives an EAP/AKA notification (section 4.3) that		If the peer receives an EAP-AKA notification (Section 4.3) that
	indicates failure, then the peer MUST no longer accept the EAP-		indicates failure, then the peer MUST no longer accept the EAP-
	Success packet even if the server authentication was successfully		Success packet even if the server authentication was successfully
	completed.		completed.
	4.5. Key Generation		4.5 Key Generation
	This section specifies how keying material is generated.		This section specifies how keying material is generated.
	On EAP AKA full authentication, a Master Key (MK) is derived from		On EAP-AKA full authentication, a Master Key (MK) is derived from the
	the underlying UMTS AKA values (CK and IK keys), and the identity as		underlying UMTS AKA values (CK and IK keys), and the identity as
	follows.		follows.
	MK = SHA1(Identity|IK|CK)		MK = SHA1(Identity|IK|CK)
	In the formula above, the "|" character denotes concatenation.		In the formula above, the "|" character denotes concatenation.
	Identity denotes the peer identity string without any terminating		Identity denotes the peer identity string without any terminating
	null characters. It is the identity from the AT_IDENTITY attribute		null characters. It is the identity from the AT_IDENTITY attribute
	from the last EAP-Response/AKA-Identity packet, or, if AT_IDENTITY		from the last EAP-Response/AKA-Identity packet, or, if AT_IDENTITY
	was not used, the identity from the EAP-Response/Identity packet.		was not used, the identity from the EAP-Response/Identity packet. The
	The identity string is included as-is, without any changes and		identity string is included as-is, without any changes and including
	including the possible identity decoration. The hash function SHA-1		the possible identity decoration. The hash function SHA-1 is
	is specified in [SHA-1].		specified in [SHA-1].
	The Master Key is fed into a Pseudo-Random number Function (PRF),		The Master Key is fed into a Pseudo-Random number Function (PRF),
	which generates separate Transient EAP Keys (TEKs) for protecting		which generates separate Transient EAP Keys (TEKs) for protecting
	EAP AKA packets, as well as a Master Session Key (MSK) for link		EAP-AKA packets, as well as a Master Session Key (MSK) for link layer
	layer security and an Extended Master Session Key (EMSK) for other		security and an Extended Master Session Key (EMSK) for other
	purposes. On re-authentication, the same TEKs MUST be used for		purposes. On fast re-authentication, the same TEKs MUST be used for
	protecting EAP packets, but a new MSK and a new EMSK MUST be derived		protecting EAP packets, but a new MSK and a new EMSK MUST be derived
	from the original MK and new values exchanged in the re-		from the original MK and new values exchanged in the fast
	authentication.		re-authentication.
	EAP AKA requires two TEKs for its own purposes, the authentication		EAP-AKA requires two TEKs for its own purposes, the authentication
	key K_aut to be used with the AT_MAC attribute, and the encryption		key K_aut to be used with the AT_MAC attribute, and the encryption
	key K_encr, to be used with the AT_ENCR_DATA attribute. The same		key K_encr, to be used with the AT_ENCR_DATA attribute. The same
	K_aut and K_encr keys are used in full authentication and subsequent		K_aut and K_encr keys are used in full authentication and subsequent
	re-authentications.		fast re-authentications.
	Key derivation is based on the random number generation specified in		Key derivation is based on the random number generation specified in
	NIST Federal Information Processing Standards (FIPS) Publication		NIST Federal Information Processing Standards (FIPS) Publication
	186-2 [PRF]. The pseudo-random number generator is specified in the		186-2 [PRF]. The pseudo-random number generator is specified in the
	change notice 1 (2001 October 5) of [PRF] (Algorithm 1). As		change notice 1 (2001 October 5) of [PRF] (Algorithm 1). As specified
	specified in the change notice (page 74), when Algorithm 1 is used		in the change notice (page 74), when Algorithm 1 is used as a
	as a general-purpose pseudo-random number generator, the "mod q"		general-purpose pseudo-random number generator, the "mod q" term in
	term in step 3.3 is omitted. The function G used in the algorithm is		step 3.3 is omitted. The function G used in the algorithm is
	constructed via Secure Hash Standard as specified in Appendix 3.3 of		constructed via Secure Hash Standard as specified in Appendix 3.3 of
	the standard. It should be noted that the function G is very similar		the standard. It should be noted that the function G is very similar
	to SHA-1, but the message padding is different. Please refer to		to SHA-1, but the message padding is different. Please refer to [PRF]
	[PRF] for full details. For convenience, the random number algorithm		for full details. For convenience, the random number algorithm with
	with the correct modification is cited in Annex A.		the correct modification is cited in Annex A.
	EAP AKA Authentication 27 October, 2003
	160-bit XKEY and XVAL values are used, so b = 160. On each full		160-bit XKEY and XVAL values are used, so b = 160. On each full
	authentication, the Master Key is used as the initial secret seed-		authentication, the Master Key is used as the initial secret seed-key
	key XKEY. The optional user input values (XSEED_j) in step 3.1 are		XKEY. The optional user input values (XSEED_j) in step 3.1 are set to
	set to zero.		zero.
	The resulting 320-bit random numbers x_0, x_1, ..., x_m-1 are		On full authentication, the resulting 320-bit random numbers x_0,
	concatenated and partitioned into suitable-sized chunks and used as		x_1, ..., x_m-1 are concatenated and partitioned into suitable-sized
	keys in the following order: K_encr (128 bits), K_aut (128 bits),		chunks and used as keys in the following order: K_encr (128 bits),
	Master Session Key (64 bytes), Extended Master Session Key (64		K_aut (128 bits), Master Session Key (64 bytes), Extended Master
	bytes).		Session Key (64 bytes).
			On fast re-authentication, the same pseudo-random number generator
			can be used to generate a new Master Session Key and a new Extended
			Master Session Key. The seed value XKEY' is calculated as follows:
	On re-authentication, the same pseudo-random number generator can be
	used to generate a new Master Session Key and new Initialization
	Vectors. The seed value XKEY' is calculated as follows:
	XKEY' = SHA1(Identity|counter|NONCE_S| MK)		XKEY' = SHA1(Identity|counter|NONCE_S| MK)
	In the formula above, the Identity denotes the re-authentication		In the formula above, the Identity denotes the fast re-authentication
	identity, without any terminating null characters, from the		identity, without any terminating null characters, from the
	AT_IDENTITY attribute of the EAP-Response/AKA-Identity packet, or,		AT_IDENTITY attribute of the EAP-Response/AKA-Identity packet, or, if
	if EAP-Response/AKA-Identity was not used on re-authentication, the		EAP-Response/AKA-Identity was not used on fast re-authentication, the
	identity string from the EAP-Response/Identity packet. The counter		identity string from the EAP-Response/Identity packet. The counter
	denotes the counter value from AT_COUNTER attribute used in the EAP-		denotes the counter value from AT_COUNTER attribute used in the
	Response/AKA-Reauthentication packet. The counter is used in network		EAP-Response/AKA-Reauthentication packet. The counter is used in
	byte order. NONCE_S denotes the 16-byte NONCE_S value from the		network byte order. NONCE_S denotes the 16-byte random NONCE_S value
	AT_NONCE_S attribute used in the EAP-Request/AKA-Reauthentication		from the AT_NONCE_S attribute used in the EAP-Request/
	packet. The MK is the Master Key derived on the preceding full		AKA-Reauthentication packet. The MK is the Master Key derived on the
	authentication. The pseudo-random number generator is run with the		preceding full authentication.
	new seed value XKEY', and the resulting 320-bit random numbers x_0,
	x_1, ..., x_m-1 are concatenated and partitioned into 64-byte chunks		On fast re-authentication, the pseudo-random number generator is run
	and used as the new 64-byte Master Session Key and the new 64-byte		with the new seed value XKEY', and the resulting 320-bit random
	Extended Master Session Key.		numbers x_0, x_1, ..., x_m-1 are concatenated and partitioned into
			64-byte chunks and used as the new 64-byte Master Session Key and the
			new 64-byte Extended Master Session Key. Note that because K_encr and
			K_aut are not derived on fast re-authentication, the Master Session
			Key and the Extended Master Session key are obtained from the
			beginning of the key stream x_0, x_1, ....
	The first 32 bytes of the MSK can be used as the Pairwise Master Key		The first 32 bytes of the MSK can be used as the Pairwise Master Key
	(PMK) for IEEE 802.11i.		(PMK) for IEEE 802.11i.
	When the RADIUS attributes specified in [RFC 2548] are used to		When the RADIUS attributes specified in [RFC2548] are used to
	transport keying material, then the first 32 bytes of the MSK		transport keying material, then the first 32 bytes of the MSK
	correspond to MS-MPPE-RECV-KEY and the second 32 bytes to MS-MPPE-		correspond to MS-MPPE-RECV-KEY and the second 32 bytes to
	SEND-KEY. In this case, only 64 bytes of keying material (the MSK)		MS-MPPE-SEND-KEY. In this case, only 64 bytes of keying material (the
	are used.		MSK) are used.
	5. Message Format and Protocol Extensibility		5. Message Format and Protocol Extensibility
	5.1. Message Format		5.1 Message Format
	As specified in [EAP], EAP packets begin with the Code, Identifiers,		As specified in [EAP], EAP packets begin with the Code, Identifiers,
	Length, and Type fields, which are followed by EAP method specific		Length, and Type fields, which are followed by EAP method specific
	Type-Data. The Code field in the EAP header is set to 1 for EAP		Type-Data. The Code field in the EAP header is set to 1 for EAP
	requests, and to 2 for EAP Responses. The usage of the Length and		requests, and to 2 for EAP Responses. The usage of the Length and
	Identifier fields in the EAP header is also specified in [EAP]. In		Identifier fields in the EAP header is also specified in [EAP]. In
	EAP/AKA, the Type field is set to 23.		EAP-AKA, the Type field is set to 23.
	EAP AKA Authentication 27 October, 2003
	In EAP/AKA, the Type-Data begins with an EAP/AKA header that		In EAP-AKA, the Type-Data begins with an EAP-AKA header that consists
	consists of a 1-octet Subtype field, and a 2-octet reserved field.		of a 1-octet Subtype field, and a 2-octet reserved field. The Subtype
	The Subtype values used in EAP/AKA are defined in Section 8. The		values used in EAP-AKA are defined in Section 8. The formats of the
	formats of the EAP header and the EAP/AKA header are shown below.		EAP header and the EAP-AKA header are shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Code | Identifier | Length |		| Code | Identifier | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Subtype | Reserved |		| Type | Subtype | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The rest of the Type-Data, immediately following the EAP/AKA header,		The rest of the Type-Data, immediately following the EAP-AKA header,
	consists of attributes that are encoded in Type, Length, Value		consists of attributes that are encoded in Type, Length, Value
	format. The figure below shows the generic format of an attribute.		format. The figure below shows the generic format of an attribute.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|Attribute Type | Length | Value...		|Attribute Type | Length | Value...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Attribute Type		Attribute Type
	Indicates the particular type of attribute. The attribute type		Indicates the particular type of attribute. The attribute type
	values are listed in Section 8.		values are listed in
			Section 8
			.
	Length		Length
	Indicates the length of this attribute in multiples of 4 bytes.		Indicates the length of this attribute in multiples of 4 bytes.
	The maximum length of an attribute is 1024 bytes. The length		The maximum length of an attribute is 1024 bytes. The length
	includes the Attribute Type and Length bytes.		includes the Attribute Type and Length bytes.
	Value		Value
			The particular data associated with this attribute. This field is
			always included and it is two or more bytes in length. The type
			and length fields determine the format and length of the value
			field.
	The particular data associated with this attribute. This field is		Attributes numbered within the range 0 through 127 are called
	always included and it is two or more bytes in length. The type		non-skippable attributes. When an EAP-AKA peer encounters a
	and length fields determine the format and length of the value		non-skippable attribute type that the peer does not recognize, the
	field.		peer MUST send the EAP-Response/AKA-Client-Error packet, and the
			authentication exchange terminates. If an EAP-AKA server encounters a
	Attributes numbered within the range 0 through 127 are called non-		non-skippable attribute that the server does not recognize, then the
	skippable attributes. When an EAP/AKA peer encounters a non-		server sends EAP-Request/AKA-Notification packet with an
	skippable attribute type that the peer does not recognize, the peer		AT_NOTIFICATION code that implies general failure (0 or 16384
	MUST send the EAP-Response/AKA-Client-Error packet, and the		depending on the phase of the exchange), and the authentication
	authentication exchange terminates. If an EAP/AKA server encounters
	a non-skippable attribute that the server does not recognize, then
	the server sends the EAP Failure packet and the authentication
	exchange terminates.		exchange terminates.
	When an attribute numbered in the range 128 through 255 is		When an attribute numbered in the range 128 through 255 is
	encountered but not recognized that particular attribute is ignored,		encountered but not recognized that particular attribute is ignored,
	EAP AKA Authentication 27 October, 2003
	but the rest of the attributes and message data MUST still be		but the rest of the attributes and message data MUST still be
	processed. The Length field of the attribute is used to skip the		processed. The Length field of the attribute is used to skip the
	attribute value when searching for the next attribute. These		attribute value when searching for the next attribute. These
	attributes are called skippable attributes.		attributes are called skippable attributes.
	Unless otherwise specified, the order of the attributes in an EAP		Unless otherwise specified, the order of the attributes in an EAP AKA
	AKA message is insignificant, and an EAP AKA implementation should		message is insignificant, and an EAP-AKA implementation should not
	not assume a certain order to be used.		assume a certain order to be used.
	Attributes can be encapsulated within other attributes. In other		Attributes can be encapsulated within other attributes. In other
	words, the value field of an attribute type can be specified to		words, the value field of an attribute type can be specified to
	contain other attributes.		contain other attributes.
	5.2. Protocol Extensibility		5.2 Protocol Extensibility
	EAP/AKA can be extended by specifying new attribute types. If		EAP-AKA can be extended by specifying new attribute types. If
	skippable attributes are used, it is possible to extend the protocol		skippable attributes are used, it is possible to extend the protocol
	without breaking old implementations. As specified in Section 7.4,		without breaking old implementations. As specified in Section 7.13,
	if new attributes are specified for EAP-Request/AKA-Identity or EAP-		if new attributes are specified for EAP-Request/AKA-Identity or
	Response/AKA-Identity, then the AT_CHECKCODE MUST be used to		EAP-Response/AKA-Identity, then the AT_CHECKCODE MUST be used to
	integrity protect the new attributes.		integrity protect the new attributes.
	When specifying new attributes, it should be noted that EAP/AKA does		When specifying new attributes, it should be noted that EAP-AKA does
	not support message fragmentation. Hence, the sizes of the new		not support message fragmentation. Hence, the sizes of the new
	extensions MUST be limited so that the maximum transfer unit (MTU)		extensions MUST be limited so that the maximum transfer unit (MTU) of
	of the underlying lower layer is not exceeded. According to [EAP],		the underlying lower layer is not exceeded. According to [EAP], lower
	lower layers must provide an EAP MTU of 1020 bytes or greater, so		layers must provide an EAP MTU of 1020 bytes or greater, so any
	any extensions to EAP/AKA SHOULD NOT exceed the EAP MTU of 1020		extensions to EAP-AKA SHOULD NOT exceed the EAP MTU of 1020 bytes.
	bytes.
	EAP/AKA packets do not include a version field. However, should		EAP-AKA packets do not include a version field. However, should there
	there be a reason to revise this protocol in the future, new non-		be a reason to revise this protocol in the future, new non-skippable
	skippable or skippable attributes could be specified in order to		or skippable attributes could be specified in order to implement
	implement revised EAP/AKA versions in a backward-compatible manner.		revised EAP-AKA versions in a backward-compatible manner. It is
	It is possible to introduce version negotiation in the EAP-		possible to introduce version negotiation in the EAP-Request/
	Request/AKA-Identity and EAP-Response/AKA-Identity messages by		AKA-Identity and EAP-Response/AKA-Identity messages by specifying new
	specifying new skippable attributes.		skippable attributes.
	6. Messages		6. Messages
	This section specifies the messages used in EAP/AKA. It specifies		This section specifies the messages used in EAP-AKA. It specifies
	when a message may be transmitted or accepted, which attributes are		when a message may be transmitted or accepted, which attributes are
	allowed in a message, which attributes are required in a message,		allowed in a message, which attributes are required in a message, and
	and other message specific details. Message format is specified in		other message specific details. Message format is specified in
	Section 5.1.		Section 5.1.
	6.1. EAP-Request/AKA-Identity		6.1 EAP-Request/AKA-Identity
	The EAP/AKA-Identity roundtrip MAY used for obtaining the peer		The EAP/AKA-Identity roundtrip MAY used for obtaining the peer
	identity to the server. As discussed in Section 4.1, several AKA-		identity to the server. As discussed in Section 4.1, several
	Identity rounds may be required in order to obtain a valid peer		AKA-Identity rounds may be required in order to obtain a valid peer
	identity.		identity.
	EAP AKA Authentication 27 October, 2003
	The server MUST include one of the following identity requesting		The server MUST include one of the following identity requesting
	attributes: AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ, AT_ANY_ID_REQ.		attributes: AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ, AT_ANY_ID_REQ.
	These three attributes are mutually exclusive, so the server MUST		These three attributes are mutually exclusive, so the server MUST NOT
	NOT include more than one of the attributes.		include more than one of the attributes.
	If the server has previously issued an EAP-Request/AKA-Identity		If the server has previously issued an EAP-Request/AKA-Identity
	message with the AT_PERMANENT_ID_REQ attribute, and if the server		message with the AT_PERMANENT_ID_REQ attribute, and if the server has
	has received a response from the peer, then the server MUST NOT		received a response from the peer, then the server MUST NOT issue a
	issue a new EAP-Request/AKA-Identity packet.		new EAP-Request/AKA-Identity packet.
	If the server has previously issued an EAP-Request/AKA-Identity		If the server has previously issued an EAP-Request/AKA-Identity
	message with the AT_FULLAUTH_ID_REQ attribute, and if the server has		message with the AT_FULLAUTH_ID_REQ attribute, and if the server has
	received a response from the peer, then the server MUST NOT issue a		received a response from the peer, then the server MUST NOT issue a
	new EAP-Request/AKA-Identity packet with the AT_ANY_ID_REQ or		new EAP-Request/AKA-Identity packet with the AT_ANY_ID_REQ or
	AT_FULLAUTH_ID_REQ attributes.		AT_FULLAUTH_ID_REQ attributes.
	If the server has previously issued an EAP-Request/AKA-Identity		If the server has previously issued an EAP-Request/AKA-Identity
	message with the AT_ANY_ID_REQ attribute, and if the server has		message with the AT_ANY_ID_REQ attribute, and if the server has
	received a response from the peer, then the server MUST NOT issue a		received a response from the peer, then the server MUST NOT issue a
	new EAP-Request/AKA-Identity packet with the AT_ANY_ID_REQ.		new EAP-Request/AKA-Identity packet with the AT_ANY_ID_REQ.
	This message MUST NOT include AT_MAC, AT_IV, or AT_ENCR_DATA.		This message MUST NOT include AT_MAC, AT_IV, or AT_ENCR_DATA.
	6.2. EAP-Response/AKA-Identity		6.2 EAP-Response/AKA-Identity
	The peer sends EAP-Response/AKA-Identity in response to a valid EAP-		The peer sends EAP-Response/AKA-Identity in response to a valid EAP-
	Request/AKA-Identity from the server.		Request/AKA-Identity from the server.
	The peer MUST include the AT_IDENTITY attribute. The usage of		The peer MUST include the AT_IDENTITY attribute. The usage of
	AT_IDENITY is defined in Section 4.1.		AT_IDENITY is defined in Section 4.1.
	This message MUST NOT include AT_MAC, AT_IV, or AT_ENCR_DATA.		This message MUST NOT include AT_MAC, AT_IV, or AT_ENCR_DATA.
	6.3. EAP-Request/AKA-Challenge		6.3 EAP-Request/AKA-Challenge
	The server sends the EAP-Request/AKA-Challenge on full		The server sends the EAP-Request/AKA-Challenge on full authentication
	authentication after successfully obtaining the subscriber identity.		after successfully obtaining the subscriber identity.
	The AT_RAND attribute MUST be included.		The AT_RAND attribute MUST be included.
	AT_MAC MUST be included. In EAP-Request/AKA-Challenge, there is no		AT_MAC MUST be included. In EAP-Request/AKA-Challenge, there is no
	message-specific data covered by the MAC, see Section 7.2.		message-specific data covered by the MAC, see Section 7.15.
			The AT_RESULT_IND attribute MAY be included. The usage of this
			attribute is discussed in Section 4.3.2.
	The AT_CHECKCODE attribute MAY be included, and in certain cases		The AT_CHECKCODE attribute MAY be included, and in certain cases
	specified in Section 7.4, it MUST be included.		specified in Section 7.13, it MUST be included.
	The EAP-Request/AKA-Challenge packet MAY include encrypted		The EAP-Request/AKA-Challenge packet MAY include encrypted attributes
	attributes for identity privacy and for communicating the next re-		for identity privacy and for communicating the next re-
	authentication identity. In this case, the AT_IV and AT_ENCR_DATA		authentication identity. In this case, the AT_IV and AT_ENCR_DATA
	attributes are included (Section 7.3).		attributes are included (Section 7.12).
	The plaintext of the AT_ENCR_DATA value field consist of nested		The plaintext of the AT_ENCR_DATA value field consist of nested
	attributes. The nested attributes MAY include AT_PADDING (as		attributes. The nested attributes MAY include AT_PADDING (as
	specified in Section 7.3). If the server supports identity privacy		specified in Section 7.12). If the server supports identity privacy
	EAP AKA Authentication 27 October, 2003
	and wants to communicate a pseudonym to the peer for the next full		and wants to communicate a pseudonym to the peer for the next full
	authentication, then the nested encrypted attributes include the		authentication, then the nested encrypted attributes include the
	AT_NEXT_PSEUDONYM attribute. If the server supports re-		AT_NEXT_PSEUDONYM attribute. If the server supports re-
	authentication and wants to communicate a re-authentication identity		authentication and wants to communicate a fast re-authentication
	to the peer, then the nested encrypted attributes include the		identity to the peer, then the nested encrypted attributes include
	AT_NEXT_REAUTH_ID attribute. Later versions of this protocol MAY		the AT_NEXT_REAUTH_ID attribute. Later versions of this protocol MAY
	specify additional attributes to be included within the encrypted		specify additional attributes to be included within the encrypted
	data.		data.
	6.4. EAP-Response/AKA-Challenge		When processing this message, the peer MUST process AT_RAND and
			AT_AUTN before processing other attributes. Only if these attributes
			are verified to be valid, the peer derives keys and verifies AT_MAC.
			The operation in case an error occurs is specified in Section 4.4.1.
			6.4 EAP-Response/AKA-Challenge
	The peer sends EAP-Response/AKA-Challenge in response to a valid		The peer sends EAP-Response/AKA-Challenge in response to a valid
	EAP-Request/AKA-Challenge.		EAP-Request/AKA-Challenge.
	The AT_MAC attribute MUST be included. In EAP-Response/AKA-		Sending this packet indicates, that the peer has successfully
	Challenge, there is no message-specific data covered by the MAC, see		authenticated the server and that the EAP exchange will be accepted
	Section 7.2.		by the peer's local policy. Hence, if these conditions are not met,
			then the peer MUST NOT send EAP-Response/AKA-Challenge, but the peer
			MUST send EAP-Response/AKA-Client-Error.
			The AT_MAC attribute MUST be included. In EAP-Response/AKA-Challenge,
			there is no message-specific data covered by the MAC, see Section
			7.15.
	The AT_RES attribute MUST be included.		The AT_RES attribute MUST be included.
	The AT_CHECKCODE attribute MAY be included, and in certain cases		The AT_CHECKCODE attribute MAY be included, and in certain cases
	specified in Section 7.4, it MUST be included.		specified in Section 7.13, it MUST be included.
			The AT_RESULT_IND attribute MAY be included, if it was included in
			EAP-Request/AKA-Challenge. The usage of this attribute is discussed
			in Section 4.3.2.
	Later versions of this protocol MAY make use of the AT_ENCR_DATA and		Later versions of this protocol MAY make use of the AT_ENCR_DATA and
	AT_IV attributes in this message to include encrypted (skippable)		AT_IV attributes in this message to include encrypted (skippable)
	attributes. The EAP server MUST process EAP-Response/AKA-Challenge		attributes. The EAP server MUST process EAP-Response/AKA-Challenge
	messages that include these attributes even if the server did not		messages that include these attributes even if the server did not
	implement these optional attributes.		implement these optional attributes.
	6.5. EAP-Response/AKA-Authentication-Reject		6.5 EAP-Response/AKA-Authentication-Reject
	The peer sends the EAP-Response/AKA-Authentication-Reject packet if		The peer sends the EAP-Response/AKA-Authentication-Reject packet if
	it does not accept the AUTN parameter. This version of the protocol		it does not accept the AUTN parameter. This version of the protocol
	does not specify any attributes for this message. Future versions of		does not specify any attributes for this message. Future versions of
	the protocol MAY specify attributes for this message.		the protocol MAY specify attributes for this message.
	The AT_MAC, AT_ENCR_DATA, or AT_IV attributes MUST NOT be used in		The AT_MAC, AT_ENCR_DATA, or AT_IV attributes MUST NOT be used in
	this message.		this message.
	6.6. EAP-Response/AKA-Synchronization-Failure		6.6 EAP-Response/AKA-Synchronization-Failure
	The peer sends the EAP-Response/AKA-Synchronization-Failure, when		The peer sends the EAP-Response/AKA-Synchronization-Failure, when the
	the sequence number in the AUTN parameter is incorrect.		sequence number in the AUTN parameter is incorrect.
	The peer MUST include the AT_AUTS attribute. Future versions of the		The peer MUST include the AT_AUTS attribute. Future versions of the
	protocol MAY specify other additional attributes for this message.		protocol MAY specify other additional attributes for this message.
	The AT_MAC, AT_ENCR_DATA, or AT_IV attributes MUST NOT be used in		The AT_MAC, AT_ENCR_DATA, or AT_IV attributes MUST NOT be used in
	this message.		this message.
	6.7. EAP-Request/AKA-Reauthentication		6.7 EAP-Request/AKA-Reauthentication
	EAP AKA Authentication 27 October, 2003
	The server sends the EAP-Request/AKA-Reauthentication message if it		The server sends the EAP-Request/AKA-Reauthentication message if it
	wants to use re-authentication, and if it has received a valid re-		wants to use fast re-authentication, and if it has received a valid
	authentication identity in EAP-Response/Identity or EAP-		fast re-authentication identity in EAP-Response/Identity or
	Response/AKA-Identity.		EAP-Response/AKA-Identity.
	The AT_MAC attribute MUST be included. No message-specific data is		The AT_MAC attribute MUST be included. No message-specific data is
	included in the MAC calculation, see Section 7.2.		included in the MAC calculation, see Section 7.15.
			The AT_RESULT_IND attribute MAY be included. The usage of this
			attribute is discussed in Section 4.3.2.
	The AT_CHECKCODE attribute MAY be included, and in certain cases		The AT_CHECKCODE attribute MAY be included, and in certain cases
	specified in Section 7.4, it MUST be included.		specified in Section 7.13, it MUST be included.
	The AT_IV and AT_ENCR_DATA attributes MUST be included. The		The AT_IV and AT_ENCR_DATA attributes MUST be included. The plaintext
	plaintext consists of the following nested encrypted attributes,		consists of the following nested encrypted attributes, which MUST be
	which MUST be included: AT_COUNTER and AT_NONCE_S. In addition, the		included: AT_COUNTER and AT_NONCE_S. In addition, the nested
	nested encrypted attributes MAY include the following attributes:		encrypted attributes MAY include the following attributes:
	AT_NEXT_REAUTH_ID and AT_PADDING.		AT_NEXT_REAUTH_ID and AT_PADDING.
	6.8. EAP-Response/AKA-Reauthentication		6.8 EAP-Response/AKA-Reauthentication
	The client sends the EAP-Response/AKA-Reauthentication packet in		The client sends the EAP-Response/AKA-Reauthentication packet in
	response to a valid EAP-Request/AKA-Reauthentication.		response to a valid EAP-Request/AKA-Reauthentication.
	The AT_MAC attribute MUST be included. For EAP-Response/AKA-		The AT_MAC attribute MUST be included. For EAP-Response/AKA-
	Reauthentication, the MAC code is calculated over the following		Reauthentication, the MAC code is calculated over the following data:
	data: EAP packet| NONCE_S. The EAP packet is represented as		EAP packet| NONCE_S. The EAP packet is represented as specified in
	specified in Section 5.1. It is followed by the 16-byte NONCE_S		Section 5.1. It is followed by the 16-byte NONCE_S value from the
	value from the server's AT_NONCE_S attribute.		server's AT_NONCE_S attribute.
	The AT_CHECKCODE attribute MAY be included, and in certain cases		The AT_CHECKCODE attribute MAY be included, and in certain cases
	specified in Section 7.4, it MUST be included.		specified in Section 7.13, it MUST be included.
	The AT_IV and AT_ENCR_DATA attributes MUST be included. The nested		The AT_IV and AT_ENCR_DATA attributes MUST be included. The nested
	encrypted attributes MUST include the AT_COUNTER attribute. The		encrypted attributes MUST include the AT_COUNTER attribute. The
	AT_COUNTER_TOO_SMALL attribute MAY be included in the nested		AT_COUNTER_TOO_SMALL attribute MAY be included in the nested
	encrypted attributes, and it is included in cases specified in		encrypted attributes, and it is included in cases specified in
	Section 4.2. The AT_PADDING attribute MAY be included.		Section 4.2. The AT_PADDING attribute MAY be included.
	6.9. EAP-Response/AKA-Client-Error		The AT_RESULT_IND attribute MAY be included, if it was included in
			EAP-Request/AKA-Reauthentication. The usage of this attribute is
			discussed in Section 4.3.2.
			Sending this packet without AT_COUNTER_TOO_SMALL indicates, that the
			peer has successfully authenticated the server and that the EAP
			exchange will be accepted by the peer's local policy. Hence, if these
			conditions are not met, then the peer MUST NOT send EAP-Response/
			AKA-Reauthentication, but the peer MUST send EAP-Response/
			AKA-Client-Error.
			6.9 EAP-Response/AKA-Client-Error
	The peer sends EAP-Response/AKA-Client-Error in error cases, as		The peer sends EAP-Response/AKA-Client-Error in error cases, as
	specified in Section 4.4.1.		specified in Section 4.4.1.
	The AT_CLIENT_ERROR_CODE attribute MUST be included.		The AT_CLIENT_ERROR_CODE attribute MUST be included. The AT_MAC,
	The AT_MAC, AT_IV, or AT_ENCR_DATA attributes MUST NOT be used with		AT_IV, or AT_ENCR_DATA attributes MUST NOT be used with this packet.
	this packet.
	6.10. EAP-Request/AKA-Notification		6.10 EAP-Request/AKA-Notification
	The usage of this message is specified in Section 4.3.		The usage of this message is specified in Section 4.3.
	The AT_NOTIFICATION attribute MUST be included.		The AT_NOTIFICATION attribute MUST be included.
	EAP AKA Authentication 27 October, 2003		The AT_MAC attribute MUST be included if the P bit of the
			AT_NOTIFICATION code is set to zero, and MUST NOT be included if the
			P bit is set to one. The P bit is discussed in in Section 4.3.
	The AT_MAC attribute is included in cases discussed in Section 4.3.
	No message-specific data is included in the MAC calculation. See		No message-specific data is included in the MAC calculation. See
	Section 7.2.		Section 7.15.
	Later versions of this protocol MAY make use of the AT_ENCR_DATA and		If EAP-Request/AKA-Notification is used on a fast re-authentication
	AT_IV attributes in this message to include encrypted (skippable)		exchange, and if the P bit in AT_NOTIFICATION is set to zero, then
	attributes. These attributes MAY be included only if the P bit of		AT_COUNTER is used for replay protection. In this case, the
	the notification code in AT_NOTIFICATION is set to zero.		AT_ENCR_DATA and AT_IV attributes MUST be included, and the
			encapsulated plaintext attributes MUST include the AT_COUNTER
			attribute. The counter value included in AT_COUNTER MUST be the same
			as in the EAP-Request/AKA-Reauthentication packet on the same fast
			re-authentication exchange.
	6.11. EAP-Response/AKA-Notification		6.11 EAP-Response/AKA-Notification
	The usage of this message is specified in Section 4.3. Because this		The usage of this message is specified in Section 4.3. This packet is
	packet is only an acknowledgement of EAP-Request/AKA-Notification,		an acknowledgement of EAP-Request/AKA-Notification.
	it does not contain any mandatory attributes.
	The AT_MAC attribute is included in cases described in Section 4.3.		The AT_MAC attribute MUST included in cases when the P bit of the
	No message-specific data is included in the MAC calculation. See		notification code in AT_NOTIFICATION of EAP-Request/AKA-Notification
	Section 7.2.		is set to zero, and MUST NOT be included in cases when the P bit is
			set to one. The P bit is discussed in Section 4.3.
	Later versions of this protocol MAY make use of the AT_ENCR_DATA and		If EAP-Request/AKA-Notification is used on fast a re-authentication
	AT_IV attributes in this message to include encrypted (skippable)		exchange, and if the P bit in AT_NOTIFICATION is set to zero, then
	attributes. These attributes MAY be included only if the P bit of		AT_COUNTER is used for replay protection. In this case, the
	the notification code in the AT_NOTIFICATION attribute of the		AT_ENCR_DATA and AT_IV attributes MUST be included, and the
	server's EAP-Request/AKA-Notification packet is set to zero.		encapsulated plaintext attributes MUST include the AT_COUNTER
			attribute. The counter value included in AT_COUNTER MUST be the same
			as in the EAP-Request/AKA-Reauthentication packet on the same fast
			re-authentication exchange.
	7. Attributes		7. Attributes
	This section specifies the format of message attributes. The		This section specifies the format of message attributes. The
	attribute type numbers are specified in Section 8.		attribute type numbers are specified in Section 8.
	7.1. Table of Attributes		7.1 Table of Attributes
	The following table provides a guide to which attributes may be		The following table provides a guide to which attributes may be found
	found in which kinds of messages, and in what quantity. Messages are		in which kinds of messages, and in what quantity. Messages are
	denoted with numbers in parentheses as follows: (1) EAP-Request/AKA-		denoted with numbers in parentheses as follows: (1) EAP-Request/
	Identity, (2) EAP-Response/AKA-Identity, (3) EAP-Request/AKA-		AKA-Identity, (2) EAP-Response/AKA-Identity, (3) EAP-Request/
	Challenge, (4) EAP-Response/AKA-Challenge, (5) EAP-Request/AKA-		AKA-Challenge, (4) EAP-Response/AKA-Challenge, (5) EAP-Request/
	Notification, (6) EAP-Response/AKA-Notification, (7) EAP-		AKA-Notification, (6) EAP-Response/AKA-Notification, (7) EAP-
	Response/AKA-Client-Error (8) EAP-Request/AKA-Reauthentication, (9)		Response/AKA-Client-Error (8) EAP-Request/AKA-Reauthentication, (9)
	EAP-Response/AKA-Re-authentication, (10) EAP-Response/AKA-		EAP-Response/AKA-Re-authentication, (10) EAP-Response/
	Authentication-Reject, and (11) EAP-Response/AKA-Synchronization-		AKA-Authentication-Reject, and (11) EAP-Response/
	Failure. The column denoted with "E" indicates whether the attribute		AKA-Synchronization-Failure. The column denoted with "E" indicates
	is a nested attribute that MUST be included within AT_ENCR_DATA.		whether the attribute is a nested attribute that MUST be included
			within AT_ENCR_DATA.
	"0" indicates that the attribute MUST NOT be included in the
	message, "1" indicates that the attribute MUST be included in the
	message, "0-1" indicates that the attribute is sometimes included in
	the message, and "0*" indicates that the attribute is not included
	in the message in cases specified in this document, but MAY be
	included in the future versions of the protocol.
	EAP AKA Authentication 27 October, 2003		"0" indicates that the attribute MUST NOT be included in the message,
			"1" indicates that the attribute MUST be included in the message,
			"0-1" indicates that the attribute is sometimes included in the
			message, and "0*" indicates that the attribute is not included in the
			message in cases specified in this document, but MAY be included in
			the future versions of the protocol.
	Attribute (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)(11) E		Attribute (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)(11) E
	AT_MAC 0 0 1 1 0-1 0-1 0 1 1 0 0 N
	AT_IV 0 0 0-1 0* 0* 0* 0 1 1 0 0 N
	AT_ENCR_DATA 0 0 0-1 0* 0* 0* 0 1 1 0 0 N
	AT_PADDING 0 0 0-1 0* 0* 0* 0 0-1 0-1 0 0 Y
	AT_CHECKCODE 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N
	AT_PERMANENT_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N		AT_PERMANENT_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N
	AT_ANY_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N		AT_ANY_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N
	AT_FULLAUTH_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N		AT_FULLAUTH_ID_REQ 0-1 0 0 0 0 0 0 0 0 0 0 N
	AT_IDENTITY 0 0-1 0 0 0 0 0 0 0 0 0 N		AT_IDENTITY 0 0-1 0 0 0 0 0 0 0 0 0 N
	AT_RAND 0 0 1 0 0 0 0 0 0 0 0 N		AT_RAND 0 0 1 0 0 0 0 0 0 0 0 N
	AT_AUTN 0 0 1 0 0 0 0 0 0 0 0 N		AT_AUTN 0 0 1 0 0 0 0 0 0 0 0 N
	AT_RES 0 0 0 1 0 0 0 0 0 0 0 N		AT_RES 0 0 0 1 0 0 0 0 0 0 0 N
	AT_AUTS 0 0 0 0 0 0 0 0 0 0 1 N		AT_AUTS 0 0 0 0 0 0 0 0 0 0 1 N
	AT_NEXT_PSEUDONYM 0 0 0-1 0 0 0 0 0 0 0 0 Y		AT_NEXT_PSEUDONYM 0 0 0-1 0 0 0 0 0 0 0 0 Y
	AT_NEXT_REAUTH_ID 0 0 0-1 0 0 0 0 0-1 0 0 0 Y		AT_NEXT_REAUTH_ID 0 0 0-1 0 0 0 0 0-1 0 0 0 Y
	AT_COUNTER 0 0 0 0 0 0 0 1 1 0 0 Y		AT_IV 0 0 0-1 0* 0-1 0-1 0 1 1 0 0 N
			AT_ENCR_DATA 0 0 0-1 0* 0-1 0-1 0 1 1 0 0 N
			AT_PADDING 0 0 0-1 0* 0-1 0-1 0 0-1 0-1 0 0 Y
			AT_CHECKCODE 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N
			AT_RESULT_IND 0 0 0-1 0-1 0 0 0 0-1 0-1 0 0 N
			AT_MAC 0 0 1 1 0-1 0-1 0 1 1 0 0 N
			AT_COUNTER 0 0 0 0 0-1 0-1 0 1 1 0 0 Y
	AT_COUNTER_TOO_SMALL 0 0 0 0 0 0 0 0 0-1 0 0 Y		AT_COUNTER_TOO_SMALL 0 0 0 0 0 0 0 0 0-1 0 0 Y
	AT_NONCE_S 0 0 0 0 0 0 0 1 0 0 0 Y		AT_NONCE_S 0 0 0 0 0 0 0 1 0 0 0 Y
	AT_NOTIFICATION 0 0 0 0 1 0 0 0 0 0 0 N		AT_NOTIFICATION 0 0 0 0 1 0 0 0 0 0 0 N
	AT_CLIENT_ERROR_CODE 0 0 0 0 0 0 1 0 0 0 0 N		AT_CLIENT_ERROR_CODE 0 0 0 0 0 0 1 0 0 0 0 N
	It should be noted that attributes AT_PERMANENT_ID_REQ,		It should be noted that attributes AT_PERMANENT_ID_REQ, AT_ANY_ID_REQ
	AT_ANY_ID_REQ and AT_FULLAUTH_ID_REQ are mutually exclusive, so that		and AT_FULLAUTH_ID_REQ are mutually exclusive, so that only one of
	only one of them can be included at the same time. If one of the		them can be included at the same time. If one of the attributes AT_IV
	attributes AT_IV and AT_ENCR_DATA is included, then both of the		and AT_ENCR_DATA is included, then both of the attributes MUST be
	attributes MUST be included.		included.
	7.2. AT_MAC
	The AT_MAC attribute is used for EAP/AKA message authentication.
	Section 6 specifies which messages AT_MAC MUST be included.
	The value field of the AT_MAC attribute contains two reserved bytes
	followed by a keyed message authentication code (MAC). The MAC is
	calculated over the whole EAP packet, concatenated with optional
	message-specific data, with the exception that the value field of
	the MAC attribute is set to zero when calculating the MAC. The EAP
	packet includes the EAP header that begins with the Code field, the
	EAP/AKA header that begins with the Subtype field, and all the
	attributes, as specified in Section 5.1. The reserved bytes in
	AT_MAC are set to zero when sending and ignored on reception. The
	contents of the message-specific data that may be included in the
	MAC calculation are specified separately for each EAP/AKA message in
	Section 6.
	The format of the AT_MAC attribute is shown below.		7.2 AT_PERMANENT_ID_REQ
	EAP AKA Authentication 27 October, 2003		The format of the AT_PERMANENT_ID_REQ attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_MAC | Length = 5 | Reserved |		|AT_PERM..._REQ | Length = 1 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |
	| MAC |
	| |
	| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The MAC algorithm is HMAC-SHA1-128 [RFC 2104] keyed hash value. (The		The use of the AT_PERMANENT_ID_REQ is defined in Section 4.1. The
	HMAC-SHA1-128 value is obtained from the 20-byte HMAC-SHA1 value by		value field only contains two reserved bytes, which are set to zero
	truncating the output to 16 bytes. Hence, the length of the MAC is		on sending and ignored on reception.
	16 bytes.) The derivation of the authentication key (K_aut) used in
	the calculation of the MAC is specified in Section 4.5.
	When the AT_MAC attribute is included in an EAP/AKA message, the
	recipient MUST process the AT_MAC attribute before looking at any
	other attributes. If the message authentication code is invalid,
	then the recipient MUST ignore all other attributes in the message
	and operate as specified in Section 4.4.
	7.3. AT_IV, AT_ENCR_DATA and AT_PADDING
	AT_IV and AT_ENCR_DATA attributes can be used to transmit encrypted
	information between the EAP/SIM peer and server.
	The value field of AT_IV contains two reserved bytes followed by a
	16-byte initialization vector required by the AT_ENCR_DATA
	attribute. The reserved bytes are set to zero when sending and
	ignored on reception. The AT_IV attribute MUST be included if and
	only if the AT_ENCR_DATA is included. Section 4.4 specifies the
	operation if a packet that does not meet this condition is
	encountered.
	The sender of the AT_IV attribute chooses the initialization vector
	by random. The sender MUST NOT reuse the initialization vector value
	from previous EAP AKA packets and the sender MUST choose it freshly
	for each AT_IV attribute. The sender SHOULD use a good source of
	randomness to generate the initialization vector. Please see [RFC
	1750] for more information about generating random numbers for
	security applications. The format of AT_IV is shown below.
	EAP AKA Authentication 27 October, 2003
	0 1 2 3		7.3 AT_ANY_ID_REQ
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_IV | Length = 5 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |
	| Initialization Vector |
	| |
	| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of the AT_ENCR_DATA attribute consists of two		The format of the AT_ANY_ID_REQ attribute is shown below.
	reserved bytes followed by cipher text bytes encrypted using the
	Advanced Encryption Standard (AES) [AES] in the Cipher Block
	Chaining (CBC) mode of operation using the initialization vector
	from the AT_IV attribute. The reserved bytes are set to zero when
	sending and ignored on reception. Please see [CBC] for a description
	of the CBC mode. The format of the AT_ENCR_DATA attribute is shown
	below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_ENCR_DATA | Length | Reserved |		|AT_ANY_ID_REQ | Length = 1 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |
	. Encrypted Data .
	. .
	| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The derivation of the encryption key (K_encr) is specified in		The use of the AT_ANY_ID_REQ is defined in Section 4.1. The value
	Section 4.5.		field only contains two reserved bytes, which are set to zero on
			sending and ignored on reception.
	The plaintext consists of nested EAP/AKA attributes.
	The encryption algorithm requires the length of the plaintext to be		7.4 AT_FULLAUTH_ID_REQ
	a multiple of 16 bytes. The sender may need to include the
	AT_PADDING attribute as the last attribute within AT_ENCR_DATA. The
	AT_PADDING attribute is not included if the total length of other
	nested attributes within the AT_ENCR_DATA attribute is a multiple of
	16 bytes. As usual, the Length of the Padding attribute includes the
	Attribute Type and Attribute Length fields. The length of the
	Padding attribute is 4, 8 or 12 bytes. It is chosen so that the
	length of the value field of the AT_ENCR_DATA attribute becomes a
	multiple of 16 bytes. The actual pad bytes in the value field are
	set to zero (0x00) on sending. The recipient of the message MUST
	verify that the pad bytes are set to zero. If this verification
	fails on the peer, then it MUST send the EAP-Response/AKA-Client-
	Error packet with the error code "unable to process packet" to
	terminate the authentication exchange. If this verification fails on
	the server, then the server sends EAP Failure, and the
	authentication exchange terminates. The format of the AT_PADDING
	attribute is shown below.
	EAP AKA Authentication 27 October, 2003		The format of the AT_FULLAUTH_ID_REQ attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_PADDING | Length | Padding... |		|AT_FULLAUTH_...| Length = 1 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |		+---------------+---------------+-------------------------------+
	| |
	| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	7.4. AT_CHECKCODE		The use of the AT_FULLAUTH_ID_REQ is defined in Section 4.1. The
			value field only contains two reserved bytes, which are set to zero
			on sending and ignored on reception.
	The AT_MAC attribute is not used in the very first EAP/AKA messages		7.5 AT_IDENTITY
	during the AKA-Identity round, because keying material has not been
	derived yet. The peer and the server may exchange one or more pairs
	of EAP/AKA messages of the Subtype AKA-Identity before keys are
	derived and before the AT_MAC attribute can be applied. The EAP/AKA-
	Identity messages may also be used upon re-authentication.
	The AT_CHECKCODE attribute MAY be used to protect the EAP/AKA-		The format of the AT_IDENTITY attribute is shown below.
	Identity messages. AT_CHECKCODE is included in EAP-Request/AKA-
	Challenge and/or EAP-Response/AKA-Challenge upon full
	authentication. In re-authentication, AT_CHECKCODE MAY be included
	in EAP-Request/AKA-Reauthentication and/or EAP-Response/AKA-
	Reauthentication. Because the AT_MAC attribute is used in these
	messages, AT_CHECKCODE will be integrity protected with AT_MAC.
	The format of the AT_CHECKCODE attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_CHECKCODE | Length | Reserved |		| AT_IDENTITY | Length | Actual Identity Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| Checkcode (0 or 20 bytes) |		. Identity .
	| |		. .
	| |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of AT_CHECKCODE begins with two reserved bytes,		The use of the AT_IDENTITY is defined in Section 4.1. The value field
	which may be followed by a 20-byte checkcode. If the checkcode is		of this attribute begins with 2-byte actual identity length, which
	not included in AT_CHECKCODE, then the attribute indicates that no		specifies the length of the identity in bytes. This field is followed
	EAP/AKA-Identity messages were exchanged. This may occur in both		by the subscriber identity of the indicated actual length. The
	full authentication and re-authentication. The reserved bytes are		identity is the permanent identity, a pseudonym identity or a fast
	set to zero when sending and ignored on reception.
	The checkcode is a hash value, calculated with SHA1 [SHA-1], over
	all EAP-Request/AKA-Identity and EAP-Response/ AKA-Identity packets
	exchanged in this authentication exchange. The packets are included
	in the order that they were transmitted, that is, starting with the
	first EAP-Request/ AKA-Identity message, followed by the
	EAP AKA Authentication 27 October, 2003
	corresponding EAP-Response/ AKA-Identity, followed by the second
	EAP-Request/ AKA-Identity (if used) etc.
	EAP packets are included in the hash calculation "as-is", as they
	were transmitted or received. All reserved bytes, padding bytes etc.
	that are specified for various attributes are included as such, and
	the receiver must not reset them to zero. No delimiter bytes,
	padding or any other framing are included between the EAP packets
	when calculating the checkcode.
	Messages are included in request/response pairs; in other words only
	full "round trips" are included. Packets that are silently discarded
	are not included. The EAP server must only include an EAP-
	Request/AKA-Identity in the calculation once it has received a
	corresponding response, with the same Identifier value.
	Retransmissions or requests to which the server does not receive
	response are not included.
	The peer must include the EAP-Request/AKA-Identity and the
	corresponding response in the calculation only if the peer receives
	a subsequent EAP-Request/AKA-Challenge, or a follow-up EAP-
	Request/AKA-Identity with different attributes (attribute types)
	than in the first EAP-Request/AKA-Identity. After sending EAP-
	Response/AKA-Identity, if the peer receives another EAP-Request/AKA-
	Identity with the same attributes as in the previous request, then
	the peer's response to the first request must have been lost. In
	this case the peer must not include the first request and its
	response in the calculation of the checkcode.
	The AT_CHECKCODE attribute is optional to implement. It is specified
	in order to allow protecting the EAP/ AKA-Identity messages and any
	future extensions to them. The implementation of AT_CHECKCODE is
	RECOMMENDED.
	If the receiver of AT_CHECKCODE implements this attribute, then the
	receiver MUST check that the checkcode is correct. If the checkcode
	is invalid, the receiver must operate as specified in Section 4.4.
	If the EAP/AKA-Identity messages are extended with new attributes
	then AT_CHECKCODE MUST be implemented and used. More specifically,
	if the server includes any other attributes than
	AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ or AT_ANY_ID_REQ in the EAP-
	Request/AKA-Identity packet, then the server MUST include
	AT_CHECKCODE in EAP-Request/AKA-Challenge or EAP-Request/AKA-
	Reauthentication. If the peer includes any other attributes than
	AT_IDENTITY in the EAP-Response/AKA-Identity message, then the peer
	MUST include AT_CHECKCODE in EAP-Response/AKA-Challenge or EAP-
	Response/AKA-Reauthentication.
	If the server implements the processing of any other attribute than
	AT_IDENTITY for the EAP-Response/AKA-Identity message, then the
	server MUST implement AT_CHECKCODE. In this case, if the server
	receives any other attribute than AT_IDENTITY in the EAP-
	Response/AKA-Identity message, then the server MUST check that
	EAP AKA Authentication 27 October, 2003
	AT_CHECKCODE is present in EAP-Response/AKA-Challenge or EAP-
	Response/AKA-Reauthentication. The operation when a mandatory
	attribute is missing is specified in Section 4.4.
	Similarly, if the peer implements the processing of any other
	attribute than AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ or
	AT_ANY_ID_REQ for the EAP-Request/AKA-Identity packet, then the peer
	MUST implement AT_CHECKCODE. In this case, if the peer receives any
	other attribute than AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ or
	AT_ANY_ID_REQ in the EAP-Request/AKA-Identity packet, then the peer
	MUST check that AT_CHECKCODE is present in EAP-Request/AKA-Challenge
	or EAP-Request/AKA-Reauthentication. The operation when a mandatory
	attribute is missing is specified in Section 4.4.
	7.5. AT_PERMANENT_ID_REQ
	The format of the AT_PERMANENT_ID_REQ attribute is shown below.
	0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|AT_PERM..._REQ | Length = 1 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The use of the AT_PERMANENT_ID_REQ is defined in Section 4.1. The
	value field only contains two reserved bytes, which are set to zero
	on sending and ignored on reception.
	7.6. AT_ANY_ID_REQ
	The format of the AT_ANY_ID_REQ attribute is shown below.
	0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|AT_ANY_ID_REQ | Length = 1 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The use of the AT_ANY_ID_REQ is defined in Section 4.1. The value
	field only contains two reserved bytes, which are set to zero on
	sending and ignored on reception.
	7.7. AT_FULLAUTH_ID_REQ
	The format of the AT_FULLAUTH_ID_REQ attribute is shown below.
	0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|AT_ANY_ID_REQ | Length = 1 | Reserved |
	+---------------+---------------+-------------------------------+
	EAP AKA Authentication 27 October, 2003
	The use of the AT_FULLAUTH_ID_REQ is defined in Section 4.1. The
	value field only contains two reserved bytes, which are set to zero
	on sending and ignored on reception.
	7.8. AT_IDENTITY
	The format of the AT_IDENTITY attribute is shown below.
	0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_IDENTITY | Length | Actual Identity Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |
	. Identity .
	. .
	| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The use of the AT_IDENTITY is defined in Section 4.1. The value
	field of this attribute begins with 2-byte actual identity length,
	which specifies the length of the identity in bytes. This field is
	followed by the subscriber identity of the indicated actual length.
	The identity is the permanent identity, a pseudonym identity or a
	re-authentication identity. The identity format is specified in		re-authentication identity. The identity format is specified in
	Section 4.1.1. The same identity format is used in the AT_IDENTITY		Section 4.1.1. The same identity format is used in the AT_IDENTITY
	attribute and the EAP-Response/Identity packet, with the exception		attribute and the EAP-Response/Identity packet, with the exception
	that the peer MUST NOT decorate the identity it includes in		that the peer MUST NOT decorate the identity it includes in
	AT_IDENTITY. The identity does not include any terminating null		AT_IDENTITY. The identity does not include any terminating null
	characters. Because the length of the attribute must be a multiple		characters. Because the length of the attribute must be a multiple of
	of 4 bytes, the sender pads the identity with zero bytes when		4 bytes, the sender pads the identity with zero bytes when necessary.
	necessary.
	7.9. AT_RAND		7.6 AT_RAND
	The format of the AT_RAND attribute is shown below.		The format of the AT_RAND attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_RAND | Length = 5 | Reserved |		| AT_RAND | Length = 5 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| RAND |		| RAND |
	| |		| |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute contains two reserved bytes		The value field of this attribute contains two reserved bytes
	followed by the AKA RAND parameter, 16 bytes (128 bits). The		followed by the AKA RAND parameter, 16 bytes (128 bits). The reserved
	reserved bytes are set to zero when sending and ignored on		bytes are set to zero when sending and ignored on reception.
	reception.
	EAP AKA Authentication 27 October, 2003
	7.10. AT_AUTN		7.7 AT_AUTN
	The format of the AT_AUTN attribute is shown below.		The format of the AT_AUTN attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_AUTN | Length = 5 | Reserved |		| AT_AUTN | Length = 5 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| AUTN |		| AUTN |
	| |		| |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute contains two reserved bytes		The value field of this attribute contains two reserved bytes
	followed by the AKA AUTN parameter, 16 bytes (128 bits). The		followed by the AKA AUTN parameter, 16 bytes (128 bits). The reserved
	reserved bytes are set to zero when sending and ignored on		bytes are set to zero when sending and ignored on reception.
	reception.
	7.11. AT_RES		7.8 AT_RES
	The format of the AT_RES attribute is shown below.		The format of the AT_RES attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_RES | Length | RES Length |		| AT_RES | Length | RES Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
	| |		| |
	| RES |		| RES |
	skipping to change at page 49, line 49 ¶		skipping to change at page 55, line 23 ¶
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute begins with the 2-byte RES Length,		The value field of this attribute begins with the 2-byte RES Length,
	which is identifies the exact length of the RES in bits. The RES		which is identifies the exact length of the RES in bits. The RES
	length is followed by the UMTS AKA RES parameter. According to [TS		length is followed by the UMTS AKA RES parameter. According to [TS
	33.105] the length of the AKA RES can vary between 32 and 128 bits.		33.105] the length of the AKA RES can vary between 32 and 128 bits.
	Because the length of the AT_RES attribute must be a multiple of 4		Because the length of the AT_RES attribute must be a multiple of 4
	bytes, the sender pads the RES with zero bits where necessary.		bytes, the sender pads the RES with zero bits where necessary.
	7.12. AT_AUTS		7.9 AT_AUTS
	The format of the AT_AUTS attribute is shown below.		The format of the AT_AUTS attribute is shown below.
	EAP AKA Authentication 27 October, 2003
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|
	| AT_AUTS | Length = 4 | |		| AT_AUTS | Length = 4 | |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
	| |		| |
	| AUTS |		| AUTS |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute contains the AKA AUTS parameter,		The value field of this attribute contains the AKA AUTS parameter,
	112 bits (14 bytes).		112 bits (14 bytes).
	7.13. AT_NEXT_PSEUDONYM		7.10 AT_NEXT_PSEUDONYM
	The format of the AT_NEXT_PSEUDONYM attribute is shown below.		The format of the AT_NEXT_PSEUDONYM attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_NEXT_PSEU..| Length | Actual Pseudonym Length |		| AT_NEXT_PSEU..| Length | Actual Pseudonym Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	. Next Pseudonym .		. Next Pseudonym .
	. .		. .
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute begins with 2-byte actual		The value field of this attribute begins with 2-byte actual pseudonym
	pseudonym length which specifies the length of the following		length which specifies the length of the following pseudonym in
	pseudonym in bytes. This field is followed by a pseudonym username		bytes. This field is followed by a pseudonym username that the peer
	that the peer can use in the next authentication. The username MUST		can use in the next authentication. The username MUST NOT include any
	NOT include any realm portion. The username does not include any		realm portion. The username does not include any terminating null
	terminating null characters. Because the length of the attribute		characters. Because the length of the attribute must be a multiple of
	must be a multiple of 4 bytes, the sender pads the pseudonym with		4 bytes, the sender pads the pseudonym with zero bytes when
	zero bytes when necessary. The username encoding MUST follow the		necessary. The username encoding MUST follow the UTF-8 transformation
	UTF-8 transformation format [RFC2279].		format [RFC2279]. This attribute MUST always be encrypted by
			encapsulating it within the AT_ENCR_DATA attribute.
	7.14. AT_NEXT_REAUTH_ID		7.11 AT_NEXT_REAUTH_ID
	The format of the AT_NEXT_REAUTH_ID attribute is shown below.		The format of the AT_NEXT_REAUTH_ID attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_NEXT_REAU..| Length | Actual Re-Auth Identity Length|		| AT_NEXT_REAU..| Length | Actual Re-Auth Identity Length|
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	. Next Re-authentication Username .		. Next Fast Re-authentication Username .
	. .		. .
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	EAP AKA Authentication 27 October, 2003		The value field of this attribute begins with 2-byte actual
			re-authentication identity length which specifies the length of the
			following fast re-authentication identity in bytes. This field is
			followed by a fast re-authentication identity that the peer can use
			in the next fast re-authentication, as described in Section 4.2. In
			environments where a realm portion is required, the fast
			re-authentication identity includes both a username portion and a
			realm name portion. The fast re-authentication identity does not
			include any terminating null characters. Because the length of the
			attribute must be a multiple of 4 bytes, the sender pads the fast
			re-authentication identity with zero bytes when necessary. The
			identity encoding MUST follow the UTF-8 transformation format
			[RFC2279]. This attribute MUST always be encrypted by encapsulating
			it within the AT_ENCR_DATA attribute.
	The value field of this attribute begins with 2-byte actual re-		7.12 AT_IV, AT_ENCR_DATA and AT_PADDING
	authentication identity length which specifies the length of the
	following re-authentication identity in bytes. This field is
	followed by a re-authentication identity that the peer can use in
	the next re-authentication, as described in Section 4.2. In
	environments where a realm portion is required, the re-
	authentication identity includes both a username portion and a realm
	name portion. The re-authentication identity does not include any
	terminating null characters. Because the length of the attribute
	must be a multiple of 4 bytes, the sender pads the re-authentication
	identity with zero bytes when necessary. The identity encoding MUST
	follow the UTF-8 transformation format [RFC2279].
	7.15. AT_COUNTER		AT_IV and AT_ENCR_DATA attributes can be used to transmit encrypted
			information between the EAP-SIM peer and server.
			The value field of AT_IV contains two reserved bytes followed by a
			16-byte initialization vector required by the AT_ENCR_DATA attribute.
			The reserved bytes are set to zero when sending and ignored on
			reception. The AT_IV attribute MUST be included if and only if the
			AT_ENCR_DATA is included. Section 4.4 specifies the operation if a
			packet that does not meet this condition is encountered.
			The sender of the AT_IV attribute chooses the initialization vector
			by random. The sender MUST NOT reuse the initialization vector value
			from previous EAP-AKA packets. The sender SHOULD use a good source of
			randomness to generate the initialization vector. Please see
			[RFC1750] for more information about generating random numbers for
			security applications. The format of AT_IV is shown below.
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| AT_IV | Length = 5 | Reserved |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| |
			| Initialization Vector |
			| |
			| |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The value field of the AT_ENCR_DATA attribute consists of two
			reserved bytes followed by cipher text bytes encrypted using the
			Advanced Encryption Standard (AES) [AES] with a 128-bit key in the
			Cipher Block Chaining (CBC) mode of operation using the
			initialization vector from the AT_IV attribute. The reserved bytes
			are set to zero when sending and ignored on reception. Please see
			[CBC] for a description of the CBC mode. The format of the
			AT_ENCR_DATA attribute is shown below.
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| AT_ENCR_DATA | Length | Reserved |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| |
			. Encrypted Data .
			. .
			| |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The derivation of the encryption key (K_encr) is specified in Section
			4.5.
			The plaintext consists of nested EAP-AKA attributes.
			The encryption algorithm requires the length of the plaintext to be a
			multiple of 16 bytes. The sender may need to include the AT_PADDING
			attribute as the last attribute within AT_ENCR_DATA. The AT_PADDING
			attribute is not included if the total length of other nested
			attributes within the AT_ENCR_DATA attribute is a multiple of 16
			bytes. As usual, the Length of the Padding attribute includes the
			Attribute Type and Attribute Length fields. The length of the Padding
			attribute is 4, 8 or 12 bytes. It is chosen so that the length of the
			value field of the AT_ENCR_DATA attribute becomes a multiple of 16
			bytes. The actual pad bytes in the value field are set to zero (00
			hexadecimal) on sending. The recipient of the message MUST verify
			that the pad bytes are set to zero. If this verification fails on the
			peer, then it MUST send the EAP-Response/AKA-Client- Error packet
			with the error code "unable to process packet" to terminate the
			authentication exchange. If this verification fails on the server,
			then the server sends the EAP-Response/AKA-Notification packet with
			an AT_NOTIFICATION code that implies failure to terminate the
			authentication exchange. The format of the AT_PADDING attribute is
			shown below.
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| AT_PADDING | Length | Padding... |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
			| |
			| |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			7.13 AT_CHECKCODE
			The AT_MAC attribute is not used in the very first EAP-AKA messages
			during the AKA-Identity round, because keying material has not been
			derived yet. The peer and the server may exchange one or more pairs
			of EAP-AKA messages of the Subtype AKA-Identity before keys are
			derived and before the AT_MAC attribute can be applied. The EAP/
			AKA-Identity messages may also be used upon fast re-authentication.
			The AT_CHECKCODE attribute MAY be used to protect the EAP/
			AKA-Identity messages. AT_CHECKCODE is included in EAP-Request/
			AKA-Challenge and/or EAP-Response/AKA-Challenge upon full
			authentication. In fast re-authentication, AT_CHECKCODE MAY be
			included in EAP-Request/AKA-Reauthentication and/or EAP-Response/
			AKA-Reauthentication. Because the AT_MAC attribute is used in these
			messages, AT_CHECKCODE will be integrity protected with AT_MAC. The
			format of the AT_CHECKCODE attribute is shown below.
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| AT_CHECKCODE | Length | Reserved |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| |
			| Checkcode (0 or 20 bytes) |
			| |
			| |
			| |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The value field of AT_CHECKCODE begins with two reserved bytes, which
			may be followed by a 20-byte checkcode. If the checkcode is not
			included in AT_CHECKCODE, then the attribute indicates that no EAP/
			AKA-Identity messages were exchanged. This may occur in both full
			authentication and fast re-authentication. The reserved bytes are set
			to zero when sending and ignored on reception.
			The checkcode is a hash value, calculated with SHA1 [SHA-1], over all
			EAP-Request/AKA-Identity and EAP-Response/ AKA-Identity packets
			exchanged in this authentication exchange. The packets are included
			in the order that they were transmitted, that is, starting with the
			first EAP-Request/ AKA-Identity message, followed by the
			corresponding EAP-Response/ AKA-Identity, followed by the second
			EAP-Request/ AKA-Identity (if used) etc.
			EAP packets are included in the hash calculation "as-is", as they
			were transmitted or received. All reserved bytes, padding bytes etc.
			that are specified for various attributes are included as such, and
			the receiver must not reset them to zero. No delimiter bytes, padding
			or any other framing are included between the EAP packets when
			calculating the checkcode.
			Messages are included in request/response pairs; in other words only
			full "round trips" are included. Packets that are silently discarded
			are not included. The EAP server must only include an EAP-Request/
			AKA-Identity in the calculation once it has received a corresponding
			response, with the same Identifier value. Retransmissions or requests
			to which the server does not receive response are not included.
			The peer must include the EAP-Request/AKA-Identity and the
			corresponding response in the calculation only if the peer receives a
			subsequent EAP-Request/AKA-Challenge, or a follow-up EAP-Request/
			AKA-Identity with different attributes (attribute types) than in the
			first EAP-Request/AKA-Identity. After sending EAP-Response/
			AKA-Identity, if the peer receives another EAP-Request/AKA-Identity
			with the same attributes as in the previous request, then the peer's
			response to the first request must have been lost. In this case the
			peer must not include the first request and its response in the
			calculation of the checkcode.
			The AT_CHECKCODE attribute is optional to implement. It is specified
			in order to allow protecting the EAP/AKA-Identity messages and any
			future extensions to them. The implementation of AT_CHECKCODE is
			RECOMMENDED.
			If the receiver of AT_CHECKCODE implements this attribute, then the
			receiver MUST check that the checkcode is correct. If the checkcode
			is invalid, the receiver must operate as specified in Section 4.4.
			If the EAP/AKA-Identity messages are extended with new attributes
			then AT_CHECKCODE MUST be implemented and used. More specifically, if
			the server includes any other attributes than AT_PERMANENT_ID_REQ,
			AT_FULLAUTH_ID_REQ or AT_ANY_ID_REQ in the EAP-Request/AKA-Identity
			packet, then the server MUST include AT_CHECKCODE in EAP-Request/
			AKA-Challenge or EAP-Request/AKA-Reauthentication. If the peer
			includes any other attributes than AT_IDENTITY in the EAP-Response/
			AKA-Identity message, then the peer MUST include AT_CHECKCODE in
			EAP-Response/AKA-Challenge or EAP-Response/AKA-Reauthentication.
			If the server implements the processing of any other attribute than
			AT_IDENTITY for the EAP-Response/AKA-Identity message, then the
			server MUST implement AT_CHECKCODE. In this case, if the server
			receives any other attribute than AT_IDENTITY in the EAP- Response/
			AKA-Identity message, then the server MUST check that AT_CHECKCODE is
			present in EAP-Response/AKA-Challenge or EAP- Response/
			AKA-Reauthentication. The operation when a mandatory attribute is
			missing is specified in Section 4.4.
			Similarly, if the peer implements the processing of any other
			attribute than AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ or
			AT_ANY_ID_REQ for the EAP-Request/AKA-Identity packet, then the peer
			MUST implement AT_CHECKCODE. In this case, if the peer receives any
			other attribute than AT_PERMANENT_ID_REQ, AT_FULLAUTH_ID_REQ or
			AT_ANY_ID_REQ in the EAP-Request/AKA-Identity packet, then the peer
			MUST check that AT_CHECKCODE is present in EAP-Request/AKA-Challenge
			or EAP-Request/AKA-Reauthentication. The operation when a mandatory
			attribute is missing is specified in Section 4.4.
			7.14 AT_RESULT_IND
			The format of the AT_RESULT_IND attribute is shown below.
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| AT_RESULT_...| Length = 1 | Reserved |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The value field of this attribute consists of two reserved bytes,
			which are set to zero upon sending and ignored upon reception. This
			attribute is always sent unencrypted, so it MUST NOT be encapsulated
			within the AT_ENCR_DATA attribute.
			7.15 AT_MAC
			The AT_MAC attribute is used for EAP-AKA message authentication.
			Section 6 specifies which messages AT_MAC MUST be included.
			The value field of the AT_MAC attribute contains two reserved bytes
			followed by a keyed message authentication code (MAC). The MAC is
			calculated over the whole EAP packet, concatenated with optional
			message-specific data, with the exception that the value field of the
			MAC attribute is set to zero when calculating the MAC. The EAP packet
			includes the EAP header that begins with the Code field, the EAP-AKA
			header that begins with the Subtype field, and all the attributes, as
			specified in Section 5.1. The reserved bytes in AT_MAC are set to
			zero when sending and ignored on reception. The contents of the
			message-specific data that may be included in the MAC calculation are
			specified separately for each EAP-AKA message in Section 6.
			The format of the AT_MAC attribute is shown below.
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| AT_MAC | Length = 5 | Reserved |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| |
			| MAC |
			| |
			| |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			The MAC algorithm is HMAC-SHA1-128 [RFC2104] keyed hash value. (The
			HMAC-SHA1-128 value is obtained from the 20-byte HMAC-SHA1 value by
			truncating the output to 16 bytes. Hence, the length of the MAC is 16
			bytes.) The derivation of the authentication key (K_aut) used in the
			calculation of the MAC is specified in Section 4.5.
			When the AT_MAC attribute is included in an EAP-AKA message, the
			recipient MUST process the AT_MAC attribute before looking at any
			other attributes, except when processing EAP-Request/AKA-Challenge.
			The processing of EAP-Request/AKA-Challenge is specified in Section
			6.3. If the message authentication code is invalid, then the
			recipient MUST ignore all other attributes in the message and operate
			as specified in Section 4.4.
			7.16 AT_COUNTER
	The format of the AT_COUNTER attribute is shown below.		The format of the AT_COUNTER attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_COUNTER | Length = 1 | Counter |		| AT_COUNTER | Length = 1 | Counter |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of the AT_COUNTER attribute consists of a 16-bit		The value field of the AT_COUNTER attribute consists of a 16-bit
	unsigned integer counter value, represented in network byte order.		unsigned integer counter value, represented in network byte order.
			This attribute MUST always be encrypted by encapsulating it within
			the AT_ENCR_DATA attribute.
	7.16. AT_COUNTER_TOO_SMALL		7.17 AT_COUNTER_TOO_SMALL
	The format of the AT_COUNTER_TOO_SMALL attribute is shown below.		The format of the AT_COUNTER_TOO_SMALL attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_COUNTER...| Length = 1 | Reserved |		| AT_COUNTER...| Length = 1 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute consists of two reserved bytes,		The value field of this attribute consists of two reserved bytes,
	which are set to zero upon sending and ignored upon reception.		which are set to zero upon sending and ignored upon reception. This
			attribute MUST always be encrypted by encapsulating it within the
			AT_ENCR_DATA attribute.
	7.17. AT_NONCE_S		7.18 AT_NONCE_S
	The format of the AT_NONCE_S attribute is shown below.		The format of the AT_NONCE_S attribute is shown below.
	EAP AKA Authentication 27 October, 2003
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_COUNTER | Length = 1 | Counter |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| AT_NONCE_S | Length = 5 | Reserved |		| AT_NONCE_S | Length = 5 | Reserved |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| |		| |
	| NONCE_S |		| NONCE_S |
	| |		| |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of the AT_NONCE_S attribute contains two reserved		The value field of the AT_NONCE_S attribute contains two reserved
	bytes followed by a random number generated by the server (16 bytes)		bytes followed by a random number generated by the server (16 bytes)
	freshly for this EAP/AKA re-authentication. The random number is		freshly for this EAP-AKA fast re-authentication. The random number is
	used as challenge for the peer and also a seed value for the new		used as challenge for the peer and also a seed value for the new
	keying material. The reserved bytes are set to zero upon sending and		keying material. The reserved bytes are set to zero upon sending and
	ignored upon reception.		ignored upon reception. This attribute MUST always be encrypted by
			encapsulating it within the AT_ENCR_DATA attribute.
	The server MUST choose the NONCE_S value freshly for each EAP/AKA		The server MUST NOT reuse the NONCE_S value from a previous EAP-AKA
	re-authentication exchange. The server SHOULD use a good source of		fast re-authentication exchange. The server SHOULD use a good source
	randomness to generate NONCE_S. Please see [RFC 1750] for more		of randomness to generate NONCE_S. Please see [RFC1750] for more
	information about generating random numbers for security		information about generating random numbers for security
	applications.		applications.
	7.18. AT_NOTIFICATION		7.19 AT_NOTIFICATION
	The format of the AT_NOTIFICATION attribute is shown below.		The format of the AT_NOTIFICATION attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|AT_NOTIFICATION| Length = 1 |F|P| Notification Code |		|AT_NOTIFICATION| Length = 1 |F|P| Notification Code |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute contains a two-byte notification		The value field of this attribute contains a two-byte notification
	code. The first and second bit (F and P) of the notification code		code. The first and second bit (F and P) of the notification code are
	are interpreted as described in Section 4.3.		interpreted as described in Section 4.3.
	The notification code values listed below have been reserved. The		The notification code values listed below have been reserved. The
	descriptions below illustrate the semantics of the notifications.		descriptions below illustrate the semantics of the notifications. The
	The peer implementation MAY use different wordings when presenting		peer implementation MAY use different wordings when presenting the
	the notifications to the user. The "requested service" depends on		notifications to the user. The "requested service" depends on the
	the environment where EAP/AKA is applied.		environment where EAP-AKA is applied.
			0 - General failure. (implies failure, used after successful
			authentication)
			16384 - General failure. (implies failure, used before
			authentication)
			32768 - User has been successfully authenticated. (does not imply
			failure, used after successful authentication). The usage of this
			code is discussed in Section 4.3.2.
	1026 - User has been temporarily denied access to the requested		1026 - User has been temporarily denied access to the requested
	service. (Implies failure, used after the challenge round)		service. (Implies failure, used after successful authentication)
	1031 - User has not subscribed to the requested service (implies		1031 - User has not subscribed to the requested service (implies
	failure, used after the challenge round)		failure, used after successful authentication)
	EAP AKA Authentication 27 October, 2003
	7.19. AT_CLIENT_ERROR_CODE		7.20 AT_CLIENT_ERROR_CODE
	The format of the AT_CLIENT_ERROR_CODE attribute is shown below.		The format of the AT_CLIENT_ERROR_CODE attribute is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|AT_CLIENT_ERR..| Length = 1 | Client Error Code |		|AT_CLIENT_ERR..| Length = 1 | Client Error Code |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	The value field of this attribute contains a two-byte client error		The value field of this attribute contains a two-byte client error
	code. The following error code values have been reserved.		code. The following error code values have been reserved.
	0 "unable to process packet": a general error code		0 "unable to process packet": a general error code
	8. IANA and Protocol Numbering Considerations		8. IANA and Protocol Numbering Considerations
	The realm name "owlan.org" has been reserved for NAI realm names		IANA has assigned the EAP type number 23 for EAP-AKA authentication.
	generated from the IMSI.
	IANA has assigned the number 23 for EAP AKA authentication.
	EAP AKA messages include a Subtype field. The following Subtypes are		EAP-AKA messages include a Subtype field. The Subtype is a new
	specified:		numbering space for which IANA administration is required. The
			following Subtypes are specified in this document:
	AKA-Challenge...................................1		AKA-Challenge...................................1
	AKA-Authentication-Reject.......................2		AKA-Authentication-Reject.......................2
	AKA-Synchronization-Failure.....................4		AKA-Synchronization-Failure.....................4
	AKA-Identity....................................5		AKA-Identity....................................5
	AKA-Notification...............................12		AKA-Notification...............................12
	AKA-Reauthentication...........................13		AKA-Reauthentication...........................13
	AKA-Client-Error...............................14		AKA-Client-Error...............................14
	EAP AKA Authentication 27 October, 2003		The messages are composed of attributes, which have attribute type
			numbers. The EAP-AKA attribute type number is a new numbering space
	The Subtype-specific data is composed of attributes, which have		for which IANA administration is required. The following attribute
	attribute type numbers. The following attribute types are specified:		types are specified in this document:
	AT_RAND.........................................1		AT_RAND.........................................1
	AT_AUTN.........................................2		AT_AUTN.........................................2
	AT_RES..........................................3		AT_RES..........................................3
	AT_AUTS.........................................4		AT_AUTS.........................................4
	AT_PADDING......................................6		AT_PADDING......................................6
	AT_PERMANENT_ID_REQ............................10		AT_PERMANENT_ID_REQ............................10
	AT_MAC.........................................11		AT_MAC.........................................11
	AT_NOTIFICATION................................12		AT_NOTIFICATION................................12
	AT_ANY_ID_REQ..................................13		AT_ANY_ID_REQ..................................13
	skipping to change at page 54, line 25 ¶		skipping to change at page 65, line 20 ¶
	AT_PERMANENT_ID_REQ............................10		AT_PERMANENT_ID_REQ............................10
	AT_MAC.........................................11		AT_MAC.........................................11
	AT_NOTIFICATION................................12		AT_NOTIFICATION................................12
	AT_ANY_ID_REQ..................................13		AT_ANY_ID_REQ..................................13
	AT_IDENTITY....................................14		AT_IDENTITY....................................14
	AT_FULLAUTH_ID_REQ.............................17		AT_FULLAUTH_ID_REQ.............................17
	AT_COUNTER.....................................19		AT_COUNTER.....................................19
	AT_COUNTER_TOO_SMALL...........................20		AT_COUNTER_TOO_SMALL...........................20
	AT_NONCE_S.....................................21		AT_NONCE_S.....................................21
	AT_CLIENT_ERROR_CODE...........................22		AT_CLIENT_ERROR_CODE...........................22
	AT_IV.........................................129		AT_IV.........................................129
	AT_ENCR_DATA..................................130		AT_ENCR_DATA..................................130
	AT_NEXT_PSEUDONYM.............................132		AT_NEXT_PSEUDONYM.............................132
	AT_NEXT_REAUTH_ID.............................133		AT_NEXT_REAUTH_ID.............................133
	AT_CHECKCODE..................................134		AT_CHECKCODE..................................134
			AT_RESULT_IND.................................135
	The AT_NOTIFICATION attribute contains a notification code value.		The AT_NOTIFICATION attribute contains a notification code value. The
	Values 1024, 1026 and 1031 have been specified in Section 7.18 of		notification code is a new numbering space for which IANA
	this document.		administration is required. Values 0, 1024, 1026, 1031, 16384 and
			32768 have been specified in Section 7.19 of this document.
	The AT_CLIENT_ERROR_CODE attribute contains a client error code.		The AT_CLIENT_ERROR_CODE attribute contains a client error code. The
	Value 0 has been specified in Section 7.19 of this document.		client error code is a new numbering space for which IANA
			administration is required. Value 0 has been specified in Section
			7.20 of this document.
	All requests for value assignment from the various number spaces		All requests for value assignment from the various number spaces
	described in this document require proper documentation, according		described in this document require proper documentation, according to
	to the "Specification Required" policy described in [RFC 2434].		the "Specification Required" policy described in [RFC2434]. Requests
	Requests must be specified in sufficient detail so that		must be specified in sufficient detail so that interoperability
	interoperability between independent implementations is possible.		between independent implementations is possible. Possible forms of
	Possible forms of documentation include, but are not limited to,		documentation include, but are not limited to, RFCs, the products of
	RFCs, the products of another standards body (e.g. 3GPP), or		another standards body (e.g. 3GPP), or permanently and readily
	permanently and readily available vendor design notes.		available vendor design notes.
	EAP AKA and EAP SIM [EAP SIM] are "sister" protocols with similar		EAP-AKA and EAP-SIM [EAP-SIM] are "sister" protocols with similar
	message structure and protocol numbering spaces. Many attributes and		message structure and protocol numbering spaces. Many attributes and
	message Subtypes have the same protocol numbers in these two		message Subtypes have the same protocol numbers in these two
	protocols. Hence, it is recommended that the same protocol number		protocols. Hence, it is recommended that the same protocol number
	value SHOULD NOT be allocated for two different purposes in EAP AKA		value SHOULD NOT be allocated for two different purposes in EAP-AKA
	and EAP SIM.		and EAP-SIM.
	9. Security Considerations		9. Security Considerations
	The EAP base protocol specification [EAP] highlights several attacks		The EAP base protocol specification [EAP] highlights several attacks
	that are possible against the EAP protocol. This section discusses		that are possible against the EAP protocol. This section discusses
			the claimed security properties of EAP-AKA as well as vulnerabilities
			and security recommendations.
	EAP AKA Authentication 27 October, 2003		9.1 Identity Protection
	the claimed security properties of EAP AKA as well as
	vulnerabilities and security recommendations.
	9.1. Identity Protection
	EAP/AKA includes optional Identity privacy support that protects the		EAP-AKA includes optional Identity privacy support that protects the
	privacy of the subscriber identity against passive eavesdropping.		privacy of the subscriber identity against passive eavesdropping.
	The mechanism cannot be used on the first exchange with a given		This document only specifies a mechanism to deliver pseudonyms from
	server, when the IMSI will have to be sent in the clear. The		the server to the peer as part of an EAP-SIM exchange. Hence, a peer
	terminal SHOULD store the pseudonym in a non-volatile memory so that		that has not yet performed any EAP-SIM exchanges does not typically
	it can be maintained across reboots. An active attacker that		have a pseudonym available. If the peer does not have a pseudonym
	impersonates the network may use the AT_PERMANENT_ID_REQ attribute		available, then the privacy mechanism cannot be used, but the
	(Section 1.1) to learn the subscriber's IMSI. However, as discussed		permanent identity will have to be sent in the clear. The terminal
	in Section 1.1, the terminal can refuse to send the cleartext IMSI		SHOULD store the pseudonym in a non-volatile memory so that it can be
	if it believes that the network should be able to recognize the		maintained across reboots. An active attacker that impersonates the
	pseudonym.		network may use the AT_PERMANENT_ID_REQ attribute (Section 4.1.2) to
			learn the subscriber's IMSI. However, as discussed in Section 4.1.2,
			the terminal can refuse to send the cleartext IMSI if it believes
			that the network should be able to recognize the pseudonym.
	If the peer and server cannot guarantee that the pseudonym will be		If the peer and server cannot guarantee that the pseudonym will be
	maintained reliably and Identity privacy is required then additional		maintained reliably and Identity privacy is required then additional
	protection from an external security mechanism such as Protected		protection from an external security mechanism such as Protected
	Extensible Authentication Protocol (PEAP) [PEAP] may be used. The		Extensible Authentication Protocol (PEAP) [PEAP] may be used. The
	benefits and the security considerations of using an external		benefits and the security considerations of using an external
	security mechanism with EAP/AKA are beyond the scope of this		security mechanism with EAP-AKA are beyond the scope of this
	document.		document.
	9.2. Mutual Authentication		9.2 Mutual Authentication
	EAP/AKA provides mutual authentication via the UMTS AKA mechanisms.		EAP-AKA provides mutual authentication via the UMTS AKA mechanisms.
	9.3. Key Derivation		9.3 Flooding the Authentication Centre
	EAP/AKA supports key derivation with 128-bit effective key strength.		The EAP-AKA server typically obtains authentication vectors from the
	The key hierarchy is specified in Section 0.		Authentication Centre (AuC). EAP-AKA introduces a new usage for the
			AuC. The protocols between the EAP-AKA server and the AuC are out of
			the scope of this document. However, it should be noted that a
			malicious EAP-AKA peer may generate a lot of protocol requests to
			mount a denial of service attack. The EAP-AKA server implementation
			SHOULD take this into account and SHOULD take steps to limit the
			traffic that it generates towards the AuC, preventing the attacker
			from flooding the AuC and from extending the denial of service attack
			from EAP-AKA to other users of the AuC.
	The Transient EAP Keys used to protect EAP AKA packets (K_encr,		9.4 Key Derivation
	K_aut) and the Master Session Keys are cryptographically separate.
	An attacker cannot derive any non-trivial information from K_encr or
	K_aut based on the Master Session Key or vice versa. An attacker
	also cannot calculate the pre-shared secret from the UMTS AKA IK,
	UMTS AKA CK, EAP AKA K_encr, EAP AKA K_aut or from the Master
	Session Key.
	9.4. Brute-Force and Dictionary Attacks		EAP-AKA supports key derivation with 128-bit effective key strength.
			The key hierarchy is specified in Section 4.5.
	The effective strength of EAP/AKA values is 128 bits, and there are		The Transient EAP Keys used to protect EAP-AKA packets (K_encr,
	no known computationally feasible brute-force attacks. Because UMTS		K_aut) and the Master Session Keys are cryptographically separate. An
	AKA is not a password protocol (the pre-shared secret must not be a		attacker cannot derive any non-trivial information from K_encr or
	weak password), EAP/AKA is not vulnerable to dictionary attacks.		K_aut based on the Master Session Key or vice versa. An attacker also
			cannot calculate the pre-shared secret from the UMTS AKA IK, UMTS AKA
			CK, EAP-AKA K_encr, EAP-AKA K_aut or from the Master Session Key.
	9.5. Integrity Protection, Replay Protection and Confidentiality		9.5 Brute-Force and Dictionary Attacks
	AT_MAC, AT_IV and AT_ENCR_DATA attributes are used to provide		The effective strength of EAP-AKA values is 128 bits, and there are
	integrity, replay and confidentiality protection for EAP/AKA		no known computationally feasible brute-force attacks. Because UMTS
	Requests and Responses. Integrity protection includes the EAP		AKA is not a password protocol (the pre-shared secret must not be a
			weak password), EAP-AKA is not vulnerable to dictionary attacks.
	EAP AKA Authentication 27 October, 2003		9.6 Protection, Replay Protection and Confidentiality
	header. Integrity protection (AT_MAC) is based on a keyed message		AT_MAC, AT_IV, AT_ENCR_DATA and AT_COUNTER attributes are used to
			provide integrity, replay and confidentiality protection for EAP-AKA
			Requests and Responses. Integrity protection with AT_MAC includes the
			EAP header. Integrity protection (AT_MAC) is based on a keyed message
	authentication code. Confidentiality (AT_ENCR_DATA and AT_IV) is		authentication code. Confidentiality (AT_ENCR_DATA and AT_IV) is
	based on a block cipher.		based on a block cipher.
	Because keys are not available in the beginning of the EAP methods,		Because keys are not available in the beginning of the EAP methods,
	the AT_MAC attribute cannot be used for protecting EAP/AKA-Identity		the AT_MAC attribute cannot be used for protecting EAP/AKA-Identity
	messages. However, the AT_CHECKCODE attribute can optionally be used		messages. However, the AT_CHECKCODE attribute can optionally be used
	to protect the integrity of the EAP/AKA-Identity roundtrip.		to protect the integrity of the EAP/AKA-Identity roundtrip.
	On full authentication, replay protection is provided by RAND and		Confidentiality protection is applied only to a part of the protocol
	AUTN values from the underlying UMTS AKA scheme. On re-		fields. The table of attributes in Section 7.1 summarizes which
	authentication, a counter and a server nonce is used to provide		fields are confidentiality protected. It should be noted that the
	replay protection.		error and notification code attributes AT_CLIENT_ERROR_CODE and
	The contents of the EAP-Response/Identity packet are implicitly		AT_NOTIFICATION are not confidential but they are transmitted in the
	integrity protected by including them in key derivation.		clear. Identity protection is discussed in Section 9.1.
	Because EAP/AKA is not a tunneling method, EAP Notification, EAP		On full authentication, replay protection of the EAP exchange is
	Success or EAP Failure packets are not confidential, integrity		provided by RAND and AUTN values from the underlying UMTS AKA scheme.
	protected or replay protected. On physically insecure networks, this		Protection against replays of EAP-AKA messages is also based on the
	may enable an attacker to mount denial of service attacks by sending		fact that messages that can include AT_MAC can only be sent once with
	false EAP Notification, EAP Success or EAP Failure packets. However,		a certain EAP-AKA Subtype, and on the fact that a different K_aut key
	the attacker cannot force the peers to believe successful		will be used for calculating AT_MAC in each full authentication
	authentication has occurred when mutual authentication failed or has		exchange.
	not happened yet.
	An eavesdropper will see the EAP Notification, EAP Success and EAP		On fast re-authentication, a counter included in AT_COUNTER and a
	Failure packets sent in the clear. With EAP AKA, confidential		server random nonce is used to provide replay protection. The
	information MUST NOT be transmitted in EAP Notification packets.		AT_COUNTER attribute is also included in EAP-AKA notifications, if
			they are used after successful authentication in order to provide
			replay protection between re-authentication exchanges.
	9.6. Negotiation Attacks		The contents of the user identity string are implicitly integrity
			protected by including them in key derivation.
	EAP/AKA does not protect the EAP-Response/Nak packet. Because		Because EAP-AKA is not a tunneling method, EAP-Request/Notification,
	EAP/AKA does not protect the EAP method negotiation, EAP method		EAP-Response/Notification, EAP-Success or EAP-Failure packets are not
	downgrading attacks may be possible, especially if the user uses the		confidential, integrity protected or replay protected. On physically
	same identity with EAP/AKA and other EAP methods.		insecure networks, this may enable an attacker to mount denial of
			service attacks by spoofing these packets. As discussed in Section
			4.4, the peer will only accept EAP-Success after successful
			authentication. Hence, the attacker cannot force the peer to believe
			successful authentication has occurred when mutual authentication
			failed or has not happened yet.
	As described in Section 5, EAP/AKA allows the protocol to be		The security considerations of EAP-AKA result indications are covered
	extended by defining new attribute types. When defining such		in Section 9.8
	attributes, it should be noted that any extra attributes included in
	EAP-Request/AKA-Identity or EAP-Response/AKA-Identity packets are
	not included in the MACs later on, and thus some other precautions
	must be taken to avoid modifications to them.
	EAP/AKA does not support ciphersuite negotiation or EAP/AKA protocol		An eavesdropper will see the EAP Notification, EAP_Success and
	version negotiation.		EAP-Failure packets sent in the clear. With EAP-AKA, confidential
			information MUST NOT be transmitted in EAP Notification packets.
	9.7. Fast Reconnect		9.7 Negotiation Attacks
	EAP/AKA includes an optional re-authentication ("fast reconnect")		EAP-AKA does not protect the EAP-Response/Nak packet. Because EAP-AKA
	procedure, as recommended in [EAP] for EAP types that are intended		does not protect the EAP method negotiation, EAP method downgrading
	for physically insecure networks.		attacks may be possible, especially if the user uses the same
			identity with EAP-AKA and other EAP methods.
	9.8. Acknowledged Result Indications		As described in Section 5, EAP-AKA allows the protocol to be extended
			by defining new attribute types. When defining such attributes, it
			should be noted that any extra attributes included in EAP-Request/
			AKA-Identity or EAP-Response/AKA-Identity packets are not included in
			the MACs later on, and thus some other precautions must be taken to
			avoid modifications to them.
	EAP AKA Authentication 27 October, 2003		EAP-AKA does not support ciphersuite negotiation or EAP-AKA protocol
			version negotiation.
	EAP/AKA does not provide acknowledged or integrity protected Success		9.8 Protected Result Indications
	or Failure indications.
	If an EAP Success or an EAP Failure packet is lost when using		EAP-AKA supports optional protected success indications, and
	EAP/AKA over an unreliable medium, and if the protocol over which		acknowledged failure indications. If a failure occurs after
	EAP/AKA is transported does not address the possible loss of Success		successful authentication, then the EAP-AKA failure indication is
	or Failure, then the peer and EAP server may end up having a		integrity and replay protected.
	different interpretation of the state of the authentication
	conversation.
	On physically insecure networks, an attacker may mount denial of		Even if an EAP-Failure packet is lost when using EAP-SIM over an
	service attacks by sending false EAP Success or EAP Failure		unreliable medium, then the EAP-SIM failure indications will help
	indications. However, the attacker cannot force the peer or the EAP		ensure that the peer and EAP server will know the other parties
	server to believe successful authentication has occurred when mutual		authentication decision. If protected success indications are used,
	authentication failed or has not happened yet.		then the loss of Success packet will also be addressed by the
			acknowledged, integrity and replay protected EAP-SIM success
			indication. If the optional success indications are not used, then
			the peer may end up believing the server succeeded authentication
			when it actually failed. Since access will not be granted in this
			case protected result indications are not needed unless the client is
			not able to realize it does not have access for an extended period of
			time.
	9.9. Man-in-the-middle Attacks		9.9 Man-in-the-middle Attacks
	In order to avoid man-in-the-middle attacks and session hijacking,		In order to avoid man-in-the-middle attacks and session hijacking,
	user data SHOULD be integrity protected on physically insecure		user data SHOULD be integrity protected on physically insecure
	networks. The EAP/AKA Master Session Key or keys derived from it MAY		networks. The EAP-AKA Master Session Key or keys derived from it MAY
	be used as the integrity protection keys, or, if an external		be used as the integrity protection keys, or, if an external security
	security mechanism such as PEAP is used, then the link integrity		mechanism such as PEAP is used, then the link integrity protection
	protection keys MAY be derived by the external security mechanism.		keys MAY be derived by the external security mechanism.
	There are man-in-the-middle attacks associated with the use of any		There are man-in-the-middle attacks associated with the use of any
	EAP method within a tunneled protocol such as PEAP, or within a		EAP method within a tunneled protocol such as PEAP, or within a
	sequence of EAP methods followed by each other. This specification		sequence of EAP methods followed by each other. This specification
	does not address these attacks. If EAP/AKA is used with a tunneling		does not address these attacks. If EAP-AKA is used with a tunneling
	protocol or as part of a sequence of methods, there should be		protocol or as part of a sequence of methods, there should be
	cryptographic binding provided between the protocols and EAP/AKA to		cryptographic binding provided between the protocols and EAP-AKA to
	prevent man-in-the-middle attacks through rogue authenticators being		prevent man-in-the-middle attacks through rogue authenticators being
	able to setup one-way authenticated tunnels. EAP/AKA Master Session		able to setup one-way authenticated tunnels. EAP-AKA Master Session
	Key MAY be used to provide the cryptographic binding. However the		Key MAY be used to provide the cryptographic binding. However the
	mechanism how the binding is provided depends on the tunneling or		mechanism how the binding is provided depends on the tunneling or
	sequencing protocol, and it is beyond the scope of this document.		sequencing protocol, and it is beyond the scope of this document.
	9.10. Generating Random Numbers		9.10 Generating Random Numbers
	An EAP/AKA implementation SHOULD use a good source of randomness to		An EAP-AKA implementation SHOULD use a good source of randomness to
	generate the random numbers required in the protocol. Please see		generate the random numbers required in the protocol. Please see
	[RFC 1750] for more information on generating random numbers for		[RFC1750] for more information on generating random numbers for
	security applications.		security applications.
	10. Security Claims		10. Security Claims
	This section provides the security claims required by [EAP].		This section provides the security claims required by [EAP].
	[a] Intended use. EAP AKA is intended for use over both physically		Auth. Mechanism: EAP-AKA is based on the UMTS AKA mechanism, which is
	insecure networks and physically or otherwise secure networks.
	Applicable media include but are not limited to PPP, IEEE 802 wired
	networks and IEEE 802.11.
	EAP AKA Authentication 27 October, 2003
	[b] Mechanism. EAP AKA is based on the UMTS AKA mechanism, which is
	an authentication and key agreement mechanism based on a symmetric		an authentication and key agreement mechanism based on a symmetric
	128-bit pre-shared secret.		128-bit pre-shared secret.
	[c] Security claims. The security properties of the method are		Ciphersuite negotiation: No
	discussed in Section 9.
	[d] Key strength. EAP/AKA supports key derivation with 128-bit		Mutual authentication: Yes
	effective key strength.
	[e] Description of key hierarchy. Please see Section 0.		Integrity protection: Yes (Section 9.6)
	[f] Indication of vulnerabilities. Vulnerabilities are discussed in		Replay protection: Yes (Section 9.6)
	Section 9.
	11. Intellectual Property Right Notices		Confidentiality: Yes, except method specific success and failure
			indications (Section 9.1, Section 9.6)
	On IPR related issues, Nokia and Ericsson refer to the their		Key derivation: Yes
	respective statements on patent licensing. Please see
	http://www.ietf.org/ietf/IPR/NOKIA and
	http://www.ietf.org/ietf/IPR/ERICSSON-General
	Acknowledgements and Contributions		Key strength: EAP-AKA supports key derivation with 128-bit effective
			key strength.
			Description of key hierarchy: Please see Section 4.5.
			Dictinary attack protection: N/A (Section 9.5)
			Fast reconnect: Yes
			Cryptographic binding: N/A
			Session independence: Yes (Section 9.4)
			Fragmentation: No
			Channel binding: No
			Indication of vulnerabilities. Vulnerabilities are discussed in
			Section 9.
			11. Acknowledgements and Contributions
	The authors wish to thank Rolf Blom of Ericsson, Bernard Aboba of		The authors wish to thank Rolf Blom of Ericsson, Bernard Aboba of
	Microsoft, Arne Norefors of Ericsson, N.Asokan of Nokia, Valtteri		Microsoft, Arne Norefors of Ericsson, N.Asokan of Nokia, Valtteri
	Niemi of Nokia, Kaisa Nyberg of Nokia, Jukka-Pekka Honkanen of		Niemi of Nokia, Kaisa Nyberg of Nokia, Jukka-Pekka Honkanen of Nokia,
	Nokia, Pasi Eronen of Nokia, Olivier Paridaens of Alcatel and Ilkka		Pasi Eronen of Nokia, Olivier Paridaens of Alcatel and Ilkka Uusitalo
	Uusitalo of Ericsson for interesting discussions in this problem		of Ericsson for interesting discussions in this problem space.
	space.
			This protocol has been partly developed in parallel with EAP-SIM
			[EAP-SIM], and hence this specification incorporates many ideas from
			EAP-SIM, and many contributions from the reviewer's of EAP-SIM.
	The attribute format is based on the extension format of Mobile IPv4		The attribute format is based on the extension format of Mobile IPv4
	[RFC 3344].		[RFC3344].
			Normative References
			[TS 33.102]
			3rd Generation Partnership Project, "3GPP Technical
			Specification 3GPP TS 33.102 V5.1.0: "Technical
			Specification Group Services and System Aspects; 3G
			Security; Security Architecture (Release 5)"", December
			2002.
			[RFC2486] Aboba, B. and M. Beadles, "The Network Access Identifier",
			RFC 2486, January 1999.
			[EAP] Blunk, L., Vollbrecht, J., Aboba, B., Carlson, J. and H.
			Levkowetz, "Extensible Authentication Protocol (EAP)",
			draft-ietf-eap-rfc2284bis-09 (work in progress), February
			2004.
			[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
			Requirement Levels", BCP 14, RFC 2119, March 1997.
			[TS 23.003]
			3rd Generation Partnership Project, "3GPP Technical
			Specification 3GPP TS 23.003 V5.5.1: "3rd Generation
			Parnership Project; Technical Specification Group Core
			Network; Numbering, addressing and identification (Release
			5)"", January 2003.
			[RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC:
			Keyed-Hashing for Message Authentication", RFC 2104,
			February 1997.
			[AES] National Institute of Standards and Technology, "Federal
			Information Processing Standards (FIPS) Publication 197,
			"Advanced Encryption Standard (AES)"", November 2001.
			http://csrc.nist.gov/publications/fips/fips197/
			fips-197.pdf
			[CBC] National Institute of Standards and Technology, "NIST
			Special Publication 800-38A, "Recommendation for Block
			Cipher Modes of Operation - Methods and Techniques"",
			December 2001.
			http://csrc.nist.gov/publications/nistpubs/800-38a/
			sp800-38a.pdf
			[SHA-1] National Institute of Standards and Technology, U.S.
			Department of Commerce, "Federal Information Processing
			Standard (FIPS) Publication 180-1, "Secure Hash
			Standard"", April 1995.
			[PRF] National Institute of Standards and Technology, "Federal
			Information Processing Standards (FIPS) Publication 186-2
			(with change notice); Digital Signature Standard (DSS)",
			January 2000.
			Available on-line at: http://csrc.nist.gov/publications/
			fips/fips186-2/fips186-2-change1.pdf
			[TS 33.105]
			3rd Generation Partnership Project, "3GPP Technical
			Specification 3GPP TS 33.105 4.1.0: "Technical
			Specification Group Services and System Aspects; 3G
			Security; Cryptographic Algorithm Requirements (Release
			4)"", June 2001.
			[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
			10646", RFC 2279, January 1998.
			[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
			IANA Considerations Section in RFCs", BCP 26, RFC 2434,
			October 1998.
			Informative References
			[RFC2548] Zorn, G., "Microsoft Vendor-specific RADIUS Attributes",
			RFC 2548, March 1999.
			[PEAP] Palekar, A., Simon, D., Zorn, G., Salowey, J., Zhou, H.
			and S. Josefsson, "Protected EAP Protocol (PEAP)",
			draft-josefsson-pppext-eap-tls-eap-07 (work in progress),
			October 2003.
			[RFC1750] Eastlake, D., Crocker, S. and J. Schiller, "Randomness
			Recommendations for Security", RFC 1750, December 1994.
			[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
			August 2002.
			[EAP-SIM] Haverinen, H. and J. Salowey, "Extensible Authentication
			Protocol Method for GSM Subscriber Identity Modules
			(EAP-SIM)", draft-haverinen-pppext-eap-sim-13 (work in
			progress), April 2004.
			[Draft 3GPP TS 23.003]
			3rd Generation Partnership Project, "Draft 3GPP Technical
			Specification 3GPP TS 23.003 V 6.1.0: "3rd Generation
			Partnership Project; Technical Specification Group Core
			Network; Numbering, addressing and identification (Release
			6)", December 2003.
			work in progress
	Authors' Addresses		Authors' Addresses
	Jari Arkko		Jari Arkko
	Ericsson		Ericsson
	02420 Jorvas Phone: +358 40 5079256		FIN-02420 Jorvas
	Finland Email: jari.arkko@ericsson.com		Finland
			Phone: +358 40 5079256
			EMail: jari.Arkko@ericsson.com
	Henry Haverinen		Henry Haverinen
	Nokia Mobile Phones		Nokia Enterprise Solutions
	P.O. Box 88		P.O. Box 12
	33721 Tampere Phone: +358 50 594 4899		FIN-40101 Jyvaskyla
	Finland E-mail: henry.haverinen@nokia.com		Finland
	EAP AKA Authentication 27 October, 2003		EMail: henry.haverinen@nokia.com
	Annex A. Pseudo-Random Number Generator		Appendix A. Pseudo-Random Number Generator
	The "|" character denotes concatenation, and "^" denotes involution.		The "|" character denotes concatenation, and "^" denotes
			exponentiation.
	Step 1: Choose a new, secret value for the seed-key, XKEY		Step 1: Choose a new, secret value for the seed-key, XKEY
	Step 2: In hexadecimal notation let		Step 2: In hexadecimal notation let
	t = 67452301 EFCDAB89 98BADCFE 10325476 C3D2E1F0		t = 67452301 EFCDAB89 98BADCFE 10325476 C3D2E1F0
	This is the initial value for H0|H1|H2|H3|H4		This is the initial value for H0|H1|H2|H3|H4
	in the FIPS SHS [SHA-1]		in the FIPS SHS <xref target="SHA-1"/>
	Step 3: For j = 0 to m - 1 do		Step 3: For j = 0 to m - 1 do
	3.1 XSEED_j = 0 /* no optional user input */		3.1 XSEED_j = 0 /* no optional user input */
	3.2 For i = 0 to 1 do		3.2 For i = 0 to 1 do
	a. XVAL = (XKEY + XSEED_j) mod 2^b		a. XVAL = (XKEY + XSEED_j) mod 2^b
	b. w_i = G(t, XVAL)		b. w_i = G(t, XVAL)
	c. XKEY = (1 + XKEY + w_i) mod 2^b		c. XKEY = (1 + XKEY + w_i) mod 2^b
	3.3 x_j = w_0|w_1		3.3 x_j = w_0|w_1
	EAP AKA Authentication 27 October, 2003		Intellectual Property Statement
	Normative References
	[TS 33.102] 3GPP Technical Specification 3GPP TS 33.102 V5.1.0:
	"Technical Specification Group Services and System Aspects; 3G
	Security; Security Architecture (Release 5)", 3rd Generation
	Partnership Project, December 2002.
	[RFC 2486] Aboba, B. and M. Beadles, "The Network Access
	Identifier", RFC 2486, January 1999.
	[EAP] L. Blunk et al., "Extensible Authentication Protocol (EAP)",
	draft-ietf-eap-rfc2284bis-05.txt, work-in-progress, September 2003.
	[RFC 2119] S. Bradner, "Key words for use in RFCs to indicate
	Requirement Levels", RFC 2119, March 1997.
	[TS 23.003] 3GPP Technical Specification 3GPP TS 23.003 V5.5.1: "3rd
	Generation Parnership Project; Technical Specification Group Core
	Network; Numbering, addressing and identification (Release 5)", 3rd
	Generation Partnership Project, January 2003
	[RFC 2104] H. Krawczyk, M. Bellare, R. Canetti, "HMAC: Keyed-Hashing
	for Message Authentication", RFC2104, February 1997.
	[SHA-1] Federal Information Processing Standard (FIPS) Publication
	180-1, "Secure Hash Standard," National Institute of Standards and
	Technology, U.S. Department of Commerce, April 17, 1995.
	[AES] Federal Information Processing Standards (FIPS) Publication
	197, "Advanced Encryption Standard (AES)", National Institute of
	Standards and Technology, November 26, 2001.
	http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
	[CBC] NIST Special Publication 800-38A, "Recommendation for Block
	Cipher Modes of Operation - Methods and Techniques", National
	Institute of Standards and Technology, December 2001.
	http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
	[TS 33.105] 3GPP Technical Specification 3GPP TS 33.105 4.1.0:
	"Technical Specification Group Services and System Aspects; 3G
	Security; Cryptographic Algorithm Requirements (Release 4)", 3rd
	Generation Partnership Project, June 2001
	[PRF] Federal Information Processing Standards (FIPS) Publication		The IETF takes no position regarding the validity or scope of any
	186-2 (with change notice), "Digital Signature Standard (DSS)",		intellectual property or other rights that might be claimed to
	National Institute of Standards and Technology, January 27, 2000		pertain to the implementation or use of the technology described in
	Available on-line at:		this document or the extent to which any license under such rights
	http://csrc.nist.gov/publications/fips/fips186-2/fips186-2-		might or might not be available; neither does it represent that it
	change1.pdf		has made any effort to identify any such rights. Information on the
			IETF's procedures with respect to rights in standards-track and
			standards-related documentation can be found in BCP-11. Copies of
			claims of rights made available for publication and any assurances of
			licenses to be made available, or the result of an attempt made to
			obtain a general license or permission for the use of such
			proprietary rights by implementors or users of this specification can
			be obtained from the IETF Secretariat.
	EAP AKA Authentication 27 October, 2003		The IETF invites any interested party to bring to its attention any
			copyrights, patents or patent applications, or other proprietary
			rights which may cover technology that may be required to practice
			this standard. Please address the information to the IETF Executive
			Director.
	[RFC 2434] T. Narten, H. Alvestrand, "Guidelines for Writing an IANA		The IETF has been notified of intellectual property rights claimed in
	Considerations Section in RFCs", RFC 2434, October 1998.		regard to some or all of the specification contained in this
			document. For more information consult the online list of claimed
			rights.
	Informative References		Full Copyright Statement
	[RFC 2548] G. Zorn, "Microsoft Vendor-specific RADIUS Attributes",		Copyright (C) The Internet Society (2004). All Rights Reserved.
	RFC 2548, March 1999
	[PEAP] H. Andersson, S. Josefsson, G. Zorn, D. Simon, A. Palekar,		This document and translations of it may be copied and furnished to
	"Protected EAP Protocol (PEAP)", draft-josefsson-pppext-eap-tls-eap-		others, and derivative works that comment on or otherwise explain it
	05.txt, work-in-progress, September 2002.		or assist in its implementation may be prepared, copied, published
			and distributed, in whole or in part, without restriction of any
			kind, provided that the above copyright notice and this paragraph are
			included on all such copies and derivative works. However, this
			document itself may not be modified in any way, such as by removing
			the copyright notice or references to the Internet Society or other
			Internet organizations, except as needed for the purpose of
			developing Internet standards in which case the procedures for
			copyrights defined in the Internet Standards process must be
			followed, or as required to translate it into languages other than
			English.
	[RFC 1750] D. Eastlake, 3rd, S. Crocker, J. Schiller, "Randomness		The limited permissions granted above are perpetual and will not be
	Recommendations for Security", RFC 1750 (Informational), December		revoked by the Internet Society or its successors or assignees.
	1994.
	[RFC 3344] C. Perkins (editor), "IP Mobility Support", RFC 3344,		This document and the information contained herein is provided on an
	August 2002.		"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
			TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
			BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
			HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
			MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	[EAP SIM] H. Haverinen, J. Salowey, "EAP SIM Authentication", draft-		Acknowledgment
	haverinen-pppext-eap-sim-12.txt, October 2003, work in progress
	[TS 23.234] Draft 3GPP Technical Specification 3GPP TS 23.234 V		Funding for the RFC Editor function is currently provided by the
	1.4.0: "Technical Specification Group Services and System Aspects;		Internet Society.
	3GPP system to Wireless Local Area Network (WLAN) Interworking;
	System Description", 3rd Generation Partnership Project, work in
	progress, January 2003.
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