< draft-ietf-cat-kerberos-pk-init-26.txt		draft-ietf-cat-kerberos-pk-init-27.txt >
	NETWORK WORKING GROUP B. Tung		NETWORK WORKING GROUP B. Tung
	Internet-Draft USC Information Sciences Institute		Internet-Draft USC Information Sciences Institute
	Expires: November 24, 2005 L. Zhu		Expires: January 20, 2006 L. Zhu
	Microsoft Corporation		Microsoft Corporation
	May 23, 2005		July 19, 2005
	Public Key Cryptography for Initial Authentication in Kerberos		Public Key Cryptography for Initial Authentication in Kerberos
	draft-ietf-cat-kerberos-pk-init-26		draft-ietf-cat-kerberos-pk-init-27
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is subject to all provisions
	of Section 3 of RFC 3667.
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
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	Drafts.		Drafts.
	skipping to change at page 1, line 38 ¶		skipping to change at page 1, line 35 ¶
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
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	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
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	This Internet-Draft will expire on November 24, 2005.		This Internet-Draft will expire on January 20, 2006.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2005).		Copyright (C) The Internet Society (2005).
	Abstract		Abstract
	This document describes protocol extensions (hereafter called PKINIT)		This document describes protocol extensions (hereafter called PKINIT)
	to the Kerberos protocol specification. These extensions provide a		to the Kerberos protocol specification. These extensions provide a
	method for integrating public key cryptography into the initial		method for integrating public key cryptography into the initial
	skipping to change at page 2, line 17 ¶		skipping to change at page 2, line 17 ¶
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Conventions Used in This Document . . . . . . . . . . . . . . 3		2. Conventions Used in This Document . . . . . . . . . . . . . . 3
	3. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3.1 Definitions, Requirements, and Constants . . . . . . . . . 4		3.1 Definitions, Requirements, and Constants . . . . . . . . . 4
	3.1.1 Required Algorithms . . . . . . . . . . . . . . . . . 4		3.1.1 Required Algorithms . . . . . . . . . . . . . . . . . 4
	3.1.2 Defined Message and Encryption Types . . . . . . . . . 5		3.1.2 Defined Message and Encryption Types . . . . . . . . . 5
	3.1.3 Algorithm Identifiers . . . . . . . . . . . . . . . . 6		3.1.3 Algorithm Identifiers . . . . . . . . . . . . . . . . 6
	3.2 PKINIT Pre-authentication Syntax and Use . . . . . . . . . 7		3.2 PKINIT Pre-authentication Syntax and Use . . . . . . . . . 7
	3.2.1 Generation of Client Request . . . . . . . . . . . . . 7		3.2.1 Generation of Client Request . . . . . . . . . . . . . 7
	3.2.2 Receipt of Client Request . . . . . . . . . . . . . . 10		3.2.2 Receipt of Client Request . . . . . . . . . . . . . . 10
	3.2.3 Generation of KDC Reply . . . . . . . . . . . . . . . 13		3.2.3 Generation of KDC Reply . . . . . . . . . . . . . . . 14
	3.2.4 Receipt of KDC Reply . . . . . . . . . . . . . . . . . 19		3.2.4 Receipt of KDC Reply . . . . . . . . . . . . . . . . . 19
	3.3 Interoperability Requirements . . . . . . . . . . . . . . 20		3.3 Interoperability Requirements . . . . . . . . . . . . . . 20
	3.4 KDC Indication of PKINIT Support . . . . . . . . . . . . . 20		3.4 KDC Indication of PKINIT Support . . . . . . . . . . . . . 21
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 21		4. Security Considerations . . . . . . . . . . . . . . . . . . . 21
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22		5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22		7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
	7.1 Normative References . . . . . . . . . . . . . . . . . . . 22		7.1 Normative References . . . . . . . . . . . . . . . . . . . 23
	7.2 Informative References . . . . . . . . . . . . . . . . . . 24		7.2 Informative References . . . . . . . . . . . . . . . . . . 24
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 24		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 25
	A. PKINIT ASN.1 Module . . . . . . . . . . . . . . . . . . . . . 25		A. PKINIT ASN.1 Module . . . . . . . . . . . . . . . . . . . . . 25
	Intellectual Property and Copyright Statements . . . . . . . . 30		Intellectual Property and Copyright Statements . . . . . . . . 31
	1. Introduction		1. Introduction
	A client typically authenticates itself to a service in Kerberos		A client typically authenticates itself to a service in Kerberos
	using three distinct though related exchanges. First, the client		using three distinct though related exchanges. First, the client
	requests a ticket-granting ticket (TGT) from the Kerberos		requests a ticket-granting ticket (TGT) from the Kerberos
	authentication server (AS). Then, it uses the TGT to request a		authentication server (AS). Then, it uses the TGT to request a
	service ticket from the Kerberos ticket-granting server (TGS).		service ticket from the Kerberos ticket-granting server (TGS).
	Usually, the AS and TGS are integrated in a single device known as a		Usually, the AS and TGS are integrated in a single device known as a
	Kerberos Key Distribution Center, or KDC. Finally, the client uses		Kerberos Key Distribution Center, or KDC. Finally, the client uses
	the service ticket to authenticate itself to the service.		the service ticket to authenticate itself to the service.
	The advantage afforded by the TGT is that the client exposes his		The advantage afforded by the TGT is that the client exposes his
	long-term secrets only once. The TGT and its associated session key		long-term secrets only once. The TGT and its associated session key
	can then be used for any subsequent service ticket requests. One		can then be used for any subsequent service ticket requests. One
	result of this is that all further authentication is independent of		result of this is that all further authentication is independent of
	the method by which the initial authentication was performed.		the method by which the initial authentication was performed.
	Consequently, initial authentication provides a convenient place to		Consequently, initial authentication provides a convenient place to
	integrate public-key cryptography into Kerberos authentication.		integrate public-key cryptography into Kerberos authentication.
	As defined in [CLAR], Kerberos authentication exchanges use		As defined in [RFC4120], Kerberos authentication exchanges use
	symmetric-key cryptography, in part for performance. One		symmetric-key cryptography, in part for performance. One
	disadvantage of using symmetric-key cryptography is that the keys		disadvantage of using symmetric-key cryptography is that the keys
	must be shared, so that before a client can authenticate itself, he		must be shared, so that before a client can authenticate itself, he
	must already be registered with the KDC.		must already be registered with the KDC.
	Conversely, public-key cryptography (in conjunction with an		Conversely, public-key cryptography (in conjunction with an
	established Public Key Infrastructure) permits authentication without		established Public Key Infrastructure) permits authentication without
	prior registration with a KDC. Adding it to Kerberos allows the		prior registration with a KDC. Adding it to Kerberos allows the
	widespread use of Kerberized applications by clients without		widespread use of Kerberized applications by clients without
	requiring them to register first with a KDC--a requirement that has		requiring them to register first with a KDC--a requirement that has
	skipping to change at page 3, line 52 ¶		skipping to change at page 3, line 52 ¶
	2. Conventions Used in This Document		2. 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 [RFC2119].		document are to be interpreted as described in [RFC2119].
	Both the AS and the TGS are referred to as the KDC.		Both the AS and the TGS are referred to as the KDC.
	In this document, the encryption key used to encrypt the enc-part		In this document, the encryption key used to encrypt the enc-part
	field of the KDC-REP in the AS-REP [CLAR] is referred to as the AS		field of the KDC-REP in the AS-REP [RFC4120] is referred to as the AS
	reply key.		reply key.
	3. Extensions		3. Extensions
	This section describes extensions to [CLAR] for supporting the use of		This section describes extensions to [RFC4120] for supporting the use
	public-key cryptography in the initial request for a ticket.		of public-key cryptography in the initial request for a ticket.
	Briefly, this document defines the following extensions to [CLAR]:		Briefly, this document defines the following extensions to [RFC4120]:
	1. The client indicates the use of public-key authentication by		1. The client indicates the use of public-key authentication by
	including a special preauthenticator in the initial request. This		including a special preauthenticator in the initial request. This
	preauthenticator contains the client's public-key data and a		preauthenticator contains the client's public-key data and a
	signature.		signature.
	2. The KDC tests the client's request against its authentication		2. The KDC tests the client's request against its authentication
	policy and trusted Certification Authorities (CAs).		policy and trusted Certification Authorities (CAs).
	3. If the request passes the verification tests, the KDC replies as		3. If the request passes the verification tests, the KDC replies as
	skipping to change at page 4, line 48 ¶		skipping to change at page 4, line 48 ¶
	Section 3.1 of this document enumerates the required algorithms and		Section 3.1 of this document enumerates the required algorithms and
	necessary extension message types. Section 3.2 describes the		necessary extension message types. Section 3.2 describes the
	extension messages in greater detail.		extension messages in greater detail.
	3.1 Definitions, Requirements, and Constants		3.1 Definitions, Requirements, and Constants
	3.1.1 Required Algorithms		3.1.1 Required Algorithms
	All PKINIT implementations MUST support the following algorithms:		All PKINIT implementations MUST support the following algorithms:
	o AS reply key enctype: AES256-CTS-HMAC-SHA1-96 etype [RFC3962].		o AS reply key enctype: aes128-cts-hmac-sha1-96 and aes256-cts-hmac-
			sha1-96 [RFC3962].
	o Signature algorithm: sha-1WithRSAEncryption [RFC3279].		o Signature algorithm: sha-1WithRSAEncryption [RFC3279].
	o AS reply key delivery method: Diffie-Hellman key exchange		o AS reply key delivery method: Diffie-Hellman key exchange
	[RFC2631].		[RFC2631].
	3.1.2 Defined Message and Encryption Types		3.1.2 Defined Message and Encryption Types
	PKINIT makes use of the following new pre-authentication types:		PKINIT makes use of the following new pre-authentication types:
	skipping to change at page 6, line 26 ¶		skipping to change at page 6, line 26 ¶
	wrapped CMS objects encoded with BER but not DER; specifically, they		wrapped CMS objects encoded with BER but not DER; specifically, they
	may not be able to decode infinite length encodings. To maximize		may not be able to decode infinite length encodings. To maximize
	interoperability, implementers SHOULD encode CMS objects used in		interoperability, implementers SHOULD encode CMS objects used in
	PKINIT with DER.		PKINIT with DER.
	3.1.3 Algorithm Identifiers		3.1.3 Algorithm Identifiers
	PKINIT does not define, but does make use of, the following algorithm		PKINIT does not define, but does make use of, the following algorithm
	identifiers.		identifiers.
	PKINIT uses the following algorithm identifiers for Diffie-Hellman		PKINIT uses the following algorithm identifier(s) for Diffie-Hellman
	key agreement [RFC3279]:		key agreement [RFC3279]:
	dhpublicnumber (Modular Exponential Diffie-Hellman [RFC2631])		dhpublicnumber (Modular Exponential Diffie-Hellman [RFC2631])
	id-ecPublicKey (Elliptic Curve Diffie-Hellman [IEEE1363])
	PKINIT uses the following signature algorithm identifiers [RFC3279]:		PKINIT uses the following signature algorithm identifiers [RFC3279]:
	sha-1WithRSAEncryption (RSA with SHA1)		sha-1WithRSAEncryption (RSA with SHA1)
	md5WithRSAEncryption (RSA with MD5)		md5WithRSAEncryption (RSA with MD5)
	id-dsa-with-sha1 (DSA with SHA1)		id-dsa-with-sha1 (DSA with SHA1)
	PKINIT uses the following encryption algorithm identifiers [RFC3447]		PKINIT uses the following encryption algorithm identifiers [RFC3447]
	for encrypting the temporary key with a public key:		for encrypting the temporary key with a public key:
	skipping to change at page 7, line 12 ¶		skipping to change at page 7, line 12 ¶
	rc2-cbc (RC2, CBC mode)		rc2-cbc (RC2, CBC mode)
	id-aes256-CBC (AES-256, CBC mode)		id-aes256-CBC (AES-256, CBC mode)
	3.2 PKINIT Pre-authentication Syntax and Use		3.2 PKINIT Pre-authentication Syntax and Use
	This section defines the syntax and use of the various pre-		This section defines the syntax and use of the various pre-
	authentication fields employed by PKINIT.		authentication fields employed by PKINIT.
	3.2.1 Generation of Client Request		3.2.1 Generation of Client Request
	The initial authentication request (AS-REQ) is sent as per [CLAR]; in		The initial authentication request (AS-REQ) is sent as per [RFC4120];
	addition, a pre-authentication data element, whose padata-type is		in addition, a pre-authentication data element, whose padata-type is
	PA_PK_AS_REQ and whose padata-value contains the DER encoding of the		PA_PK_AS_REQ and whose padata-value contains the DER encoding of the
	type PA-PK-AS-REQ, is included.		type PA-PK-AS-REQ, is included.
	PA-PK-AS-REQ ::= SEQUENCE {		PA-PK-AS-REQ ::= SEQUENCE {
	signedAuthPack [0] IMPLICIT OCTET STRING,		signedAuthPack [0] IMPLICIT OCTET STRING,
	-- Contains a CMS type ContentInfo encoded		-- Contains a CMS type ContentInfo encoded
	-- according to [RFC3852].		-- according to [RFC3852].
	-- The contentType field of the type ContentInfo		-- The contentType field of the type ContentInfo
	-- is id-signedData (1.2.840.113549.1.7.2),		-- is id-signedData (1.2.840.113549.1.7.2),
	-- and the content field is a SignedData.		-- and the content field is a SignedData.
	-- The eContentType field for the type SignedData is		-- The eContentType field for the type SignedData is
	-- id-pkauthdata (1.3.6.1.5.2.3.1), and the		-- id-pkauthdata (1.3.6.1.5.2.3.1), and the
	-- eContent field contains the DER encoding of the		-- eContent field contains the DER encoding of the
	-- type AuthPack.		-- type AuthPack.
	-- AuthPack is defined below.		-- AuthPack is defined below.
	trustedCertifiers [1] SEQUENCE OF TrustedCA OPTIONAL,		trustedCertifiers [1] SEQUENCE OF
			ExternalPrincipalIdentifier OPTIONAL,
	-- A list of CAs, trusted by the client, that can		-- A list of CAs, trusted by the client, that can
	-- be used to certify the KDC.		-- be used to certify the KDC.
	-- Each TrustedCA identifies a CA or a CA		-- Each ExternalPrincipalIdentifier identifies a CA
	-- certificate (thereby its public key).		-- or a CA certificate (thereby its public key).
	-- The information contained in the		-- The information contained in the
	-- trustedCertifiers SHOULD be used by the KDC as		-- trustedCertifiers SHOULD be used by the KDC as
	-- hints to guide its selection of an appropriate		-- hints to guide its selection of an appropriate
	-- certificate chain to return to the client.		-- certificate chain to return to the client.
	kdcPkId [2] IMPLICIT OCTET STRING		kdcPkId [2] IMPLICIT OCTET STRING
	OPTIONAL,		OPTIONAL,
	-- Contains a CMS type SignerIdentifier encoded		-- Contains a CMS type SignerIdentifier encoded
	-- according to [RFC3852].		-- according to [RFC3852].
	-- Identifies, if present, a particular KDC		-- Identifies, if present, a particular KDC
	-- public key that the client already has.		-- public key that the client already has.
	...		...
	}		}
	DHNonce ::= OCTET STRING		DHNonce ::= OCTET STRING
	TrustedCA ::= SEQUENCE {		ExternalPrincipalIdentifier ::= SEQUENCE {
	caName [0] IMPLICIT OCTET STRING,		subjectName [0] IMPLICIT OCTET STRING OPTIONAL,
	-- Contains a PKIX type Name encoded according to		-- Contains a PKIX type Name encoded according to
	-- [RFC3280].		-- [RFC3280].
			-- Identifies the certificate subject by the
	-- Identifies a CA by the CA's distinguished subject		-- distinguished subject name.
	-- name.		-- REQUIRED when there is a distinguished subject
	certificateSerialNumber [1] INTEGER OPTIONAL,		-- name present in the certificate.
	-- Specifies the CA certificate's serial number.		issuerAndSerialNumber [1] IMPLICIT OCTET STRING OPTIONAL,
	-- The defintion of the certificate serial number		-- Contains a CMS type IssuerAndSerialNumber encoded
	-- is taken from X.509 [X.509-97].		-- according to [RFC3852].
	subjectKeyIdentifier [2] OCTET STRING OPTIONAL,		-- Identifies a certificate of the subject.
	-- Identifies the CA's public key by a key		-- REQUIRED for TD-INVALID-CERTIFICATES and
			-- TD-TRUSTED-CERTIFIERS.
			subjectKeyIdentifier [2] IMPLICIT OCTET STRING OPTIONAL,
			-- Identifies the subject's public key by a key
	-- identifier. When an X.509 certificate is		-- identifier. When an X.509 certificate is
	-- referenced, this key identifier matches the X.509		-- referenced, this key identifier matches the X.509
	-- subjectKeyIdentifier extension value. When other		-- subjectKeyIdentifier extension value. When other
	-- certificate formats are referenced, the documents		-- certificate formats are referenced, the documents
	-- that specify the certificate format and their use		-- that specify the certificate format and their use
	-- with the CMS must include details on matching the		-- with the CMS must include details on matching the
	-- key identifier to the appropriate certificate		-- key identifier to the appropriate certificate
	-- field.		-- field.
			-- RECOMMENDED for TD-TRUSTED-CERTIFIERS.
	...		...
	}		}
	AuthPack ::= SEQUENCE {		AuthPack ::= SEQUENCE {
	pkAuthenticator [0] PKAuthenticator,		pkAuthenticator [0] PKAuthenticator,
	clientPublicValue [1] SubjectPublicKeyInfo OPTIONAL,		clientPublicValue [1] SubjectPublicKeyInfo OPTIONAL,
	-- Type SubjectPublicKeyInfo is defined in		-- Type SubjectPublicKeyInfo is defined in
	-- [RFC3280].		-- [RFC3280].
	-- Specifies Diffie-Hellman domain parameters		-- Specifies Diffie-Hellman domain parameters
	-- and the client's public key value [IEEE1363].		-- and the client's public key value [IEEE1363].
	skipping to change at page 8, line 47 ¶		skipping to change at page 9, line 4 ¶
	OPTIONAL,		OPTIONAL,
	-- Type AlgorithmIdentifier is defined in		-- Type AlgorithmIdentifier is defined in
	-- [RFC3280].		-- [RFC3280].
	-- List of CMS encryption types supported by the		-- List of CMS encryption types supported by the
	-- client in order of (decreasing) preference.		-- client in order of (decreasing) preference.
	clientDHNonce [3] DHNonce OPTIONAL,		clientDHNonce [3] DHNonce OPTIONAL,
	-- Present only if the client indicates that it		-- Present only if the client indicates that it
	-- wishes to reuse DH keys or to allow the KDC to		-- wishes to reuse DH keys or to allow the KDC to
	-- do so (see Section 3.2.3.1).		-- do so (see Section 3.2.3.1).
	...		...
	}		}
	PKAuthenticator ::= SEQUENCE {		PKAuthenticator ::= SEQUENCE {
	cusec [0] INTEGER (0..999999),		cusec [0] INTEGER (0..999999),
	ctime [1] KerberosTime,		ctime [1] KerberosTime,
	-- cusec and ctime are used as in [CLAR], for replay		-- cusec and ctime are used as in [RFC4120], for
	-- prevention.		-- replay prevention.
	nonce [2] INTEGER (0..4294967295),		nonce [2] INTEGER (0..4294967295),
	-- Chosen randomly; This nonce does not need to		-- Chosen randomly; This nonce does not need to
	-- match with the nonce in the KDC-REQ-BODY.		-- match with the nonce in the KDC-REQ-BODY.
	paChecksum [3] OCTET STRING,		paChecksum [3] OCTET STRING,
	-- Contains the SHA1 checksum, performed over		-- Contains the SHA1 checksum, performed over
	-- KDC-REQ-BODY.		-- KDC-REQ-BODY.
	...		...
	}		}
	The ContentInfo [RFC3852] structure for the signedAuthPack field is		The ContentInfo [RFC3852] structure for the signedAuthPack field is
	skipping to change at page 9, line 50 ¶		skipping to change at page 10, line 8 ¶
	6. The client's Diffie-Hellman public value (clientPublicValue) is		6. The client's Diffie-Hellman public value (clientPublicValue) is
	included if and only if the client wishes to use the Diffie-		included if and only if the client wishes to use the Diffie-
	Hellman key agreement method. The Diffie-Hellman domain		Hellman key agreement method. The Diffie-Hellman domain
	parameters [IEEE1363] for the client's public key are specified		parameters [IEEE1363] for the client's public key are specified
	in the algorithm field of the type SubjectPublicKeyInfo [RFC3279]		in the algorithm field of the type SubjectPublicKeyInfo [RFC3279]
	and the client's Diffie-Hellman public key value is mapped to a		and the client's Diffie-Hellman public key value is mapped to a
	subjectPublicKey (a BIT STRING) according to [RFC3279]. When		subjectPublicKey (a BIT STRING) according to [RFC3279]. When
	using the Diffie-Hellman key agreement method, implementations		using the Diffie-Hellman key agreement method, implementations
	MUST support Oakley 1024-bit Modular Exponential (MODP) well-		MUST support Oakley 1024-bit Modular Exponential (MODP) well-
	known group 2 [RFC2412] and SHOULD support Oakley 2048-bit MODP		known group 2 [RFC2412] and Oakley 2048-bit MODP well-known group
	well-known group 14 and Oakley 4096-bit MODP well-known group 16		14 [RFC3526], and SHOULD support Oakley 4096-bit MODP well-known
			group 16 [RFC3526].
	[RFC3526].
	The Diffie-Hellman field size should be chosen so as to provide		The Diffie-Hellman field size should be chosen so as to provide
	sufficient cryptographic security [RFC3766].		sufficient cryptographic security [RFC3766].
	When MODP Diffie-Hellman is used, the exponents should have at		When MODP Diffie-Hellman is used, the exponents should have at
	least twice as many bits as the symmetric keys that will be		least twice as many bits as the symmetric keys that will be
	derived from them [ODL99].		derived from them [ODL99].
	7. The client may wish to reuse DH keys or to allow the KDC to do so		7. The client may wish to reuse DH keys or to allow the KDC to do so
	(see Section 3.2.3.1). If so, then the client includes the		(see Section 3.2.3.1). If so, then the client includes the
	skipping to change at page 10, line 31 ¶		skipping to change at page 10, line 36 ¶
	Upon receiving the client's request, the KDC validates it. This		Upon receiving the client's request, the KDC validates it. This
	section describes the steps that the KDC MUST (unless otherwise		section describes the steps that the KDC MUST (unless otherwise
	noted) take in validating the request.		noted) take in validating the request.
	The KDC verifies the client's signature in the signedAuthPack field		The KDC verifies the client's signature in the signedAuthPack field
	according to [RFC3852].		according to [RFC3852].
	If, while validating the client's X.509 certificate [RFC3280], the		If, while validating the client's X.509 certificate [RFC3280], the
	KDC cannot build a certification path to validate the client's		KDC cannot build a certification path to validate the client's
	certificate, it sends back a KRB-ERROR [CLAR] message with the code		certificate, it sends back a KRB-ERROR [RFC4120] message with the
	KDC_ERR_CANT_VERIFY_CERTIFICATE. The accompanying e-data for this		code KDC_ERR_CANT_VERIFY_CERTIFICATE. The accompanying e-data for
	error message is a TYPED-DATA (as defined in [CLAR]) that contains an		this error message is a TYPED-DATA (as defined in [RFC4120]) that
	element whose data-type is TD_TRUSTED_CERTIFIERS, and whose data-		contains an element whose data-type is TD_TRUSTED_CERTIFIERS, and
	value contains the DER encoding of the type TD-TRUSTED-CERTIFIERS:		whose data-value contains the DER encoding of the type TD-TRUSTED-
			CERTIFIERS:
	TD-TRUSTED-CERTIFIERS ::= SEQUENCE OF TrustedCA		TD-TRUSTED-CERTIFIERS ::= SEQUENCE OF
			ExternalPrincipalIdentifier
	-- Identifies a list of CAs trusted by the KDC.		-- Identifies a list of CAs trusted by the KDC.
	-- Each TrustedCA identifies a CA or a CA		-- Each ExternalPrincipalIdentifier identifies a CA
	-- certificate (thereby its public key).		-- or a CA certificate (thereby its public key).
	Upon receiving this error message, the client SHOULD retry only if it		Upon receiving this error message, the client SHOULD retry only if it
	has a different set of certificates (from those of the previous		has a different set of certificates (from those of the previous
	requests) that form a certification path (or a partial path) from one		requests) that form a certification path (or a partial path) from one
	of the trust anchors acceptable by the KDC to its own certificate.		of the trust anchors acceptable by the KDC to its own certificate.
	If, while processing the certification path, the KDC determines that		If, while processing the certification path, the KDC determines that
	the signature on one of the certificates in the signedAuthPack field		the signature on one of the certificates in the signedAuthPack field
	is invalid, it returns a KRB-ERROR [CLAR] message with the code		is invalid, it returns a KRB-ERROR [RFC4120] message with the code
	KDC_ERR_INVALID_CERTIFICATE. The accompanying e-data for this error		KDC_ERR_INVALID_CERTIFICATE. The accompanying e-data for this error
	message is a TYPED-DATA that contains an element whose data-type is		message is a TYPED-DATA that contains an element whose data-type is
	TD_INVALID_CERTIFICATES, and whose data-value contains the DER		TD_INVALID_CERTIFICATES, and whose data-value contains the DER
	encoding of the type TD-INVALID-CERTIFICATES:		encoding of the type TD-INVALID-CERTIFICATES:
	TD-INVALID-CERTIFICATES ::= SEQUENCE OF OCTET STRING		TD-INVALID-CERTIFICATES ::= SEQUENCE OF
	-- Each OCTET STRING contains a CMS type		ExternalPrincipalIdentifier
	-- IssuerAndSerialNumber encoded according to		-- Each ExternalPrincipalIdentifier identifies a
	-- [RFC3852].
	-- Each IssuerAndSerialNumber identifies a
	-- certificate (sent by the client) with an invalid		-- certificate (sent by the client) with an invalid
	-- signature.		-- signature.
	If more than one X.509 certificate signature is invalid, the KDC MAY		If more than one X.509 certificate signature is invalid, the KDC MAY
	include one IssuerAndSerialNumber per invalid signature within the		include one IssuerAndSerialNumber per invalid signature within the
	TD-INVALID-CERTIFICATES.		TD-INVALID-CERTIFICATES.
	The client's X.509 certificate is validated according to [RFC3280].		The client's X.509 certificate is validated according to [RFC3280].
	Based on local policy, the KDC may also check whether any X.509		Based on local policy, the KDC may also check whether any X.509
	skipping to change at page 12, line 33 ¶		skipping to change at page 12, line 37 ¶
	}		}
	If the KDC does not have its own binding and there is no		If the KDC does not have its own binding and there is no
	KRB5PrincipalName name present in the client's X.509 certificate, or		KRB5PrincipalName name present in the client's X.509 certificate, or
	if the Kerberos name in the request does not match the		if the Kerberos name in the request does not match the
	KRB5PrincipalName in the client's X.509 certificate (including the		KRB5PrincipalName in the client's X.509 certificate (including the
	realm name), the KDC MUST return an error message with the code		realm name), the KDC MUST return an error message with the code
	KDC_ERR_CLIENT_NAME_MISMATCH. There is no accompanying e-data for		KDC_ERR_CLIENT_NAME_MISMATCH. There is no accompanying e-data for
	this error message.		this error message.
			Even if the certification path is validated and the certificate is
			mapped to the client's principal name, the KDC may decide not to
			accept the client's certificate, depending on local policy.
	The KDC MAY require the presence of an Extended Key Usage (EKU)		The KDC MAY require the presence of an Extended Key Usage (EKU)
	KeyPurposeId [RFC3280] id-pkekuoid in the extensions field of the		KeyPurposeId [RFC3280] id-pkekuoid in the extensions field of the
	client's X.509 certificate:		client's X.509 certificate:
	id-pkekuoid OBJECT IDENTIFIER ::=		id-pkekuoid OBJECT IDENTIFIER ::=
	{ iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2)		{ iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2)
	pkinit(3) pkekuoid(4) }		pkinit(3) pkekuoid(4) }
	-- PKINIT client authentication.		-- PKINIT client authentication.
	-- Key usage bits that MUST be consistent:		-- Key usage bits that MUST be consistent:
	-- digitalSignature.		-- digitalSignature.
	skipping to change at page 13, line 5 ¶		skipping to change at page 13, line 13 ¶
	If this EKU KeyPurposeId is required but it is not present or if the		If this EKU KeyPurposeId is required but it is not present or if the
	client certificate is restricted not to be used for PKINIT client		client certificate is restricted not to be used for PKINIT client
	authentication per Section 4.2.1.13 of [RFC3280], the KDC MUST return		authentication per Section 4.2.1.13 of [RFC3280], the KDC MUST return
	an error message of the code KDC_ERR_INCONSISTENT_KEY_PURPOSE. There		an error message of the code KDC_ERR_INCONSISTENT_KEY_PURPOSE. There
	is no accompanying e-data for this error message. KDCs implementing		is no accompanying e-data for this error message. KDCs implementing
	this requirement SHOULD also accept the EKU KeyPurposeId id-ms-sc-		this requirement SHOULD also accept the EKU KeyPurposeId id-ms-sc-
	logon (1.3.6.1.4.1.311.20.2.2) as meeting the requirement, as there		logon (1.3.6.1.4.1.311.20.2.2) as meeting the requirement, as there
	are a large number of X.509 client certificates deployed for use with		are a large number of X.509 client certificates deployed for use with
	PKINIT which have this EKU.		PKINIT which have this EKU.
	If for any other reasons, the client's public key is not accepted,		As a matter of local policy, the KDC MAY decide to reject requests on
	the KDC MUST return an error message with the code		the basis of the absence or presence of other specific EKU OID's.
	KDC_ERR_CLIENT_NOT_TRUSTED.
			If the client's public key is not accepted, the KDC returns an error
			message with the code KDC_ERR_CLIENT_NOT_TRUSTED.
	The KDC MUST check the timestamp to ensure that the request is not a		The KDC MUST check the timestamp to ensure that the request is not a
	replay, and that the time skew falls within acceptable limits. The		replay, and that the time skew falls within acceptable limits. The
	recommendations for clock skew times in [CLAR] apply here. If the		recommendations for clock skew times in [RFC4120] apply here. If the
	check fails, the KDC MUST return error code KRB_AP_ERR_REPEAT or		check fails, the KDC MUST return error code KRB_AP_ERR_REPEAT or
	KRB_AP_ERR_SKEW, respectively.		KRB_AP_ERR_SKEW, respectively.
	If the clientPublicValue is filled in, indicating that the client		If the clientPublicValue is filled in, indicating that the client
	wishes to use the Diffie-Hellman key agreement method, the KDC SHOULD		wishes to use the Diffie-Hellman key agreement method, the KDC SHOULD
	check to see if the key parameters satisfy its policy. If they do		check to see if the key parameters satisfy its policy. If they do
	not, it MUST return an error message with the code		not, it MUST return an error message with the code
	KDC_ERR_DH_KEY_PARAMETERS_NOT_ACCEPTED. The accompanying e-data is a		KDC_ERR_DH_KEY_PARAMETERS_NOT_ACCEPTED. The accompanying e-data is a
	TYPED-DATA that contains an element whose data-type is		TYPED-DATA that contains an element whose data-type is
	TD_DH_PARAMETERS, and whose data-value contains the DER encoding of		TD_DH_PARAMETERS, and whose data-value contains the DER encoding of
	skipping to change at page 13, line 41 ¶		skipping to change at page 13, line 51 ¶
	client SHOULD pick one to retry the request.		client SHOULD pick one to retry the request.
	If the client included a kdcPkId field in the PA-PK-AS-REQ and the		If the client included a kdcPkId field in the PA-PK-AS-REQ and the
	KDC does not possess the corresponding key, the KDC MUST ignore the		KDC does not possess the corresponding key, the KDC MUST ignore the
	kdcPkId field as if the client did not include one.		kdcPkId field as if the client did not include one.
	If there is a supportedCMSTypes field in the AuthPack, the KDC must		If there is a supportedCMSTypes field in the AuthPack, the KDC must
	check to see if it supports any of the listed types. If it supports		check to see if it supports any of the listed types. If it supports
	more than one of the types, the KDC SHOULD use the one listed first.		more than one of the types, the KDC SHOULD use the one listed first.
	If it does not support any of them, it MUST return an error message		If it does not support any of them, it MUST return an error message
	with the code KDC_ERR_ETYPE_NOSUPP [CLAR].		with the code KDC_ERR_ETYPE_NOSUPP [RFC4120].
	3.2.3 Generation of KDC Reply		3.2.3 Generation of KDC Reply
	Assuming that the client's request has been properly validated, the		Assuming that the client's request has been properly validated, the
	KDC proceeds as per [CLAR], except as follows.		KDC proceeds as per [RFC4120], except as follows.
	The KDC MUST set the initial flag and include an authorization data		The KDC MUST set the initial flag and include an authorization data
	element of ad-type [CLAR] AD_INITIAL_VERIFIED_CAS in the issued		element of ad-type [RFC4120] AD_INITIAL_VERIFIED_CAS in the issued
	ticket. The ad-data [CLAR] field contains the DER encoding of the		ticket. The ad-data [RFC4120] field contains the DER encoding of the
	type AD-INITIAL-VERIFIED-CAS:		type AD-INITIAL-VERIFIED-CAS:
	AD-INITIAL-VERIFIED-CAS ::= SEQUENCE OF TrustedCA		AD-INITIAL-VERIFIED-CAS ::= SEQUENCE OF
			ExternalPrincipalIdentifier
	-- Identifies the certification path based on which		-- Identifies the certification path based on which
	-- the client certificate was validated.		-- the client certificate was validated.
	-- Each TrustedCA identifies a CA or a CA		-- Each ExternalPrincipalIdentifier identifies a CA
	-- certificate (thereby its public key).		-- or a CA certificate (thereby its public key).
	The AS wraps any AD-INITIAL-VERIFIED-CAS data in AD-IF-RELEVANT		The AS wraps any AD-INITIAL-VERIFIED-CAS data in AD-IF-RELEVANT
	containers if the list of CAs satisfies the AS' realm's local policy		containers if the list of CAs satisfies the AS' realm's local policy
	(this corresponds to the TRANSITED-POLICY-CHECKED ticket flag		(this corresponds to the TRANSITED-POLICY-CHECKED ticket flag
	[CLAR]). Furthermore, any TGS MUST copy such authorization data from		[RFC4120]). Furthermore, any TGS MUST copy such authorization data
	tickets used within a PA-TGS-REQ of the TGS-REQ into the resulting		from tickets used within a PA-TGS-REQ of the TGS-REQ into the
	ticket. If the list of CAs satisfies the local KDC's realm's policy,		resulting ticket. If the list of CAs satisfies the local KDC's
	the TGS MAY wrap the data into the AD-IF-RELEVANT container,		realm's policy, the TGS MAY wrap the data into the AD-IF-RELEVANT
	otherwise it MAY unwrap the authorization data out of the AD-IF-		container, otherwise it MAY unwrap the authorization data out of the
	RELEVANT container.		AD-IF-RELEVANT container.
	Application servers that understand this authorization data type		Application servers that understand this authorization data type
	SHOULD apply local policy to determine whether a given ticket bearing		SHOULD apply local policy to determine whether a given ticket bearing
	such a type *not* contained within an AD-IF-RELEVANT container is		such a type *not* contained within an AD-IF-RELEVANT container is
	acceptable. (This corresponds to the AP server checking the		acceptable. (This corresponds to the AP server checking the
	transited field when the TRANSITED-POLICY-CHECKED flag has not been		transited field when the TRANSITED-POLICY-CHECKED flag has not been
	set [CLAR].) If such a data type is contained within an AD-IF-		set [RFC4120].) If such a data type is contained within an AD-IF-
	RELEVANT container, AP servers MAY apply local policy to determine		RELEVANT container, AP servers MAY apply local policy to determine
	whether the authorization data is acceptable.		whether the authorization data is acceptable.
	The content of the AS-REP is otherwise unchanged from [CLAR]. The		The content of the AS-REP is otherwise unchanged from [RFC4120]. The
	KDC encrypts the reply as usual, but not with the client's long-term		KDC encrypts the reply as usual, but not with the client's long-term
	key. Instead, it encrypts it with either a shared key derived from a		key. Instead, it encrypts it with either a shared key derived from a
	Diffie-Hellman exchange, or a generated encryption key. The contents		Diffie-Hellman exchange, or a generated encryption key. The contents
	of the PA-PK-AS-REP indicate which key delivery method is used:		of the PA-PK-AS-REP indicate which key delivery method is used:
	PA-PK-AS-REP ::= CHOICE {		PA-PK-AS-REP ::= CHOICE {
	dhInfo [0] DHRepInfo,		dhInfo [0] DHRepInfo,
	-- Selected when Diffie-Hellman key exchange is		-- Selected when Diffie-Hellman key exchange is
	-- used.		-- used.
	encKeyPack [1] IMPLICIT OCTET STRING,		encKeyPack [1] IMPLICIT OCTET STRING,
	skipping to change at page 17, line 12 ¶		skipping to change at page 17, line 19 ¶
	The AS reply key is derived as follows:		The AS reply key is derived as follows:
	1. Both the KDC and the client calculate the shared secret value as		1. Both the KDC and the client calculate the shared secret value as
	follows:		follows:
	a) When MODP Diffie-Hellman is used, let DHSharedSecret be the		a) When MODP Diffie-Hellman is used, let DHSharedSecret be the
	shared secret value. DHSharedSecret is the value ZZ as		shared secret value. DHSharedSecret is the value ZZ as
	described in Section 2.1.1 of [RFC2631].		described in Section 2.1.1 of [RFC2631].
	b) When Elliptic Curve Diffie-Hellman (ECDH) (with each party
	contributing one key pair) is used, let DHSharedSecret be the
	x-coordinate of the shared secret value (an elliptic curve
	point). DHSharedSecret is the output of operation ECSVDP-DH as
	described in Section 7.2.1 of [IEEE1363].
	DHSharedSecret is first padded with leading zeros such that the		DHSharedSecret is first padded with leading zeros such that the
	size of DHSharedSecret in octets is the same as that of the		size of DHSharedSecret in octets is the same as that of the
	modulus, then represented as a string of octets in big-endian		modulus, then represented as a string of octets in big-endian
	order.		order.
	Implementation note: Both the client and the KDC can cache the		Implementation note: Both the client and the KDC can cache the
	triple (ya, yb, DHSharedSecret), where ya is the client's public		triple (ya, yb, DHSharedSecret), where ya is the client's public
	key and yb is the KDC's public key. If both ya and yb are the		key and yb is the KDC's public key. If both ya and yb are the
	same in a later exchange, the cached DHSharedSecret can be used.		same in a later exchange, the cached DHSharedSecret can be used.
	2. Let K be the key-generation seed length [RFC3961] of the AS reply		2. Let K be the key-generation seed length [RFC3961] of the AS reply
	key whose enctype is selected according to [CLAR].		key whose enctype is selected according to [RFC4120].
	3. Define the function octetstring2key() as follows:		3. Define the function octetstring2key() as follows:
	octetstring2key(x) == random-to-key(K-truncate(		octetstring2key(x) == random-to-key(K-truncate(
	SHA1(0x00 | x) |		SHA1(0x00 | x) |
	SHA1(0x01 | x) |		SHA1(0x01 | x) |
	SHA1(0x02 | x) |		SHA1(0x02 | x) |
	...		...
	))		))
	skipping to change at page 18, line 19 ¶		skipping to change at page 18, line 23 ¶
	3.2.3.2 Using Public Key Encryption		3.2.3.2 Using Public Key Encryption
	In this case, the PA-PK-AS-REP contains a ContentInfo structure		In this case, the PA-PK-AS-REP contains a ContentInfo structure
	wrapped in an OCTET STRING. The AS reply key is encrypted in the		wrapped in an OCTET STRING. The AS reply key is encrypted in the
	encKeyPack field, which contains data of type ReplyKeyPack:		encKeyPack field, which contains data of type ReplyKeyPack:
	ReplyKeyPack ::= SEQUENCE {		ReplyKeyPack ::= SEQUENCE {
	replyKey [0] EncryptionKey,		replyKey [0] EncryptionKey,
	-- Contains the session key used to encrypt the		-- Contains the session key used to encrypt the
	-- enc-part field in the AS-REP.		-- enc-part field in the AS-REP.
	nonce [1] INTEGER (0..4294967295),		asChecksum [1] Checksum,
	-- Contains the nonce in the PKAuthenticator of the		-- Contains the checksum of the AS-REQ
	-- request.		-- corresponding to the containing AS-REP.
			-- The checksum is performed over the type AS-REQ.
			-- The protocol key [RFC3961] of the checksum is the
			-- replyKey and the key usage number is 6.
			-- If the replyKey's enctype is "newer" [RFC4120]
			-- [RFC4121], the checksum is the required
			-- checksum operation [RFC3961] for that enctype.
			-- The client MUST verify this checksum upon receipt
			-- of the AS-REP.
	...		...
	}		}
	The ContentInfo [RFC3852] structure for the encKeyPack field is		The ContentInfo [RFC3852] structure for the encKeyPack field is
	filled in as follows:		filled in as follows:
	1. The contentType field of the type ContentInfo is id-envelopedData		1. The contentType field of the type ContentInfo is id-envelopedData
	(as defined in [RFC3852]), and the content field is an		(as defined in [RFC3852]), and the content field is an
	EnvelopedData (as defined in [RFC3852]).		EnvelopedData (as defined in [RFC3852]).
	skipping to change at page 19, line 23 ¶		skipping to change at page 19, line 35 ¶
	certificates field MUST NOT contain "root" CA certificates.		certificates field MUST NOT contain "root" CA certificates.
	7. The recipientInfos field of the type EnvelopedData is a SET which		7. The recipientInfos field of the type EnvelopedData is a SET which
	MUST contain exactly one member of type KeyTransRecipientInfo.		MUST contain exactly one member of type KeyTransRecipientInfo.
	The encryptedKey of this member contains the temporary key which		The encryptedKey of this member contains the temporary key which
	is encrypted using the client's public key.		is encrypted using the client's public key.
	8. The unprotectedAttrs or originatorInfo fields of the type		8. The unprotectedAttrs or originatorInfo fields of the type
	EnvelopedData MAY be present.		EnvelopedData MAY be present.
			Implementations of this RSA encryption key delivery method are
			RECOMMENDED to support for RSA keys at least 2048 bits in size.
	3.2.4 Receipt of KDC Reply		3.2.4 Receipt of KDC Reply
	Upon receipt of the KDC's reply, the client proceeds as follows. If		Upon receipt of the KDC's reply, the client proceeds as follows. If
	the PA-PK-AS-REP contains the dhSignedData field, the client derives		the PA-PK-AS-REP contains the dhSignedData field, the client derives
	the AS reply key using the same procedure used by the KDC as defined		the AS reply key using the same procedure used by the KDC as defined
	in Section 3.2.3.1. Otherwise, the message contains the encKeyPack		in Section 3.2.3.1. Otherwise, the message contains the encKeyPack
	field, and the client decrypts and extracts the temporary key in the		field, and the client decrypts and extracts the temporary key in the
	encryptedKey field of the member KeyTransRecipientInfo, and then uses		encryptedKey field of the member KeyTransRecipientInfo, and then uses
	that as the AS reply key.		that as the AS reply key.
	In either case, the client MUST verify the signature in the		In either case, the client MUST verify the signature in the
	SignedData according to [RFC3852]. The KDC's X.509 certificate MUST		SignedData according to [RFC3852]. The KDC's X.509 certificate MUST
	be validated according to [RFC3280]. In addition, unless the client		be validated according to [RFC3280]. In addition, unless the client
	can otherwise verify that the public key used to verify the KDC's		can otherwise verify that the public key used to verify the KDC's
	signature is bound to the KDC of the target realm, the KDC's X.509		signature is bound to the KDC of the target realm, the KDC's X.509
	certificate MUST contain a Subject Alternative Name extension		certificate MUST contain a Subject Alternative Name extension
	[RFC3280] carrying an AnotherName whose type-id is id-pksan (as		[RFC3280] carrying an AnotherName whose type-id is id-pksan (as
	defined in Section 3.2.2) and whose value is a KRB5PrincipalName that		defined in Section 3.2.2) and whose value is a KRB5PrincipalName that
	matches the name of the TGS of the target realm (as defined in		matches the name of the TGS of the target realm (as defined in
	Section 7.3 of [CLAR]).		Section 7.3 of [RFC4120]).
	Based on local policy, the client MAY require that the KDC		Based on local policy, the client MAY require that the KDC
	certificate contains the EKU KeyPurposeId [RFC3280] id-pkkdcekuoid:		certificate contains the EKU KeyPurposeId [RFC3280] id-pkkdcekuoid:
	id-pkkdcekuoid OBJECT IDENTIFIER ::=		id-pkkdcekuoid OBJECT IDENTIFIER ::=
	{ iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2)		{ iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2)
	pkinit(3) pkkdcekuoid(5) }		pkinit(3) pkkdcekuoid(5) }
	-- Signing KDC responses.		-- Signing KDC responses.
	-- Key usage bits that MUST be consistent:		-- Key usage bits that MUST be consistent:
	-- digitalSignature.		-- digitalSignature.
	If all applicable checks are satisfied, the client then decrypts the		If all applicable checks are satisfied, the client then decrypts the
	enc-part field of the KDC-REP in the AS-REP using the AS reply key,		enc-part field of the KDC-REP in the AS-REP using the AS reply key,
	and then proceeds as described in [CLAR].		and then proceeds as described in [RFC4120].
	Implementation note: CAs issuing KDC certificates SHOULD place all		Implementation note: CAs issuing KDC certificates SHOULD place all
	"short" and "fully-qualified" Kerberos realm names of the KDC (one		"short" and "fully-qualified" Kerberos realm names of the KDC (one
	per GeneralName [RFC3280]) into the KDC certificate to allow maximum		per GeneralName [RFC3280]) into the KDC certificate to allow maximum
	flexibility.		flexibility.
	3.3 Interoperability Requirements		3.3 Interoperability Requirements
	The client MUST be capable of sending a set of certificates		The client MUST be capable of sending a set of certificates
	sufficient to allow the KDC to construct a certification path for the		sufficient to allow the KDC to construct a certification path for the
	skipping to change at page 20, line 43 ¶		skipping to change at page 21, line 8 ¶
	If the KDC sends all the X.509 certificates on a certification path		If the KDC sends all the X.509 certificates on a certification path
	to a trust anchor acceptable by the client, and the client can not		to a trust anchor acceptable by the client, and the client can not
	verify the KDC's public key otherwise, the client MUST be able to		verify the KDC's public key otherwise, the client MUST be able to
	process path validation for the KDC's certificate based on the		process path validation for the KDC's certificate based on the
	certificates in the reply.		certificates in the reply.
	3.4 KDC Indication of PKINIT Support		3.4 KDC Indication of PKINIT Support
	If pre-authentication is required, but was not present in the		If pre-authentication is required, but was not present in the
	request, per [CLAR] an error message with the code		request, per [RFC4120] an error message with the code
	KDC_ERR_PREAUTH_FAILED is returned and a METHOD-DATA object will be		KDC_ERR_PREAUTH_FAILED is returned and a METHOD-DATA object will be
	stored in the e-data field of the KRB-ERROR message to specify which		stored in the e-data field of the KRB-ERROR message to specify which
	pre-authentication mechanisms are acceptable. The KDC can then		pre-authentication mechanisms are acceptable. The KDC can then
	indicate the support of PKINIT by including an empty element whose		indicate the support of PKINIT by including an empty element whose
	padata-type is PA_PK_AS_REQ in that METHOD-DATA object.		padata-type is PA_PK_AS_REQ in that METHOD-DATA object.
	Otherwise if it is required by the KDC's local policy that the client		Otherwise if it is required by the KDC's local policy that the client
	must be pre-authenticated using the pre-authentication mechanism		must be pre-authenticated using the pre-authentication mechanism
	specified in this document, but no PKINIT pre-authentication was		specified in this document, but no PKINIT pre-authentication was
	present in the request, an error message with the code		present in the request, an error message with the code
	KDC_ERR_PREAUTH_FAILED SHOULD be returned.		KDC_ERR_PREAUTH_FAILED SHOULD be returned.
	KDCs MUST leave the padata-value field of the PA_PK_AS_REQ element in		KDCs MUST leave the padata-value field of the PA_PK_AS_REQ element in
	the KRB-ERROR's METHOD-DATA empty (i.e., send a zero-length OCTET		the KRB-ERROR's METHOD-DATA empty (i.e., send a zero-length OCTET
	STRING), and clients MUST ignore this and any other value. Future		STRING), and clients MUST ignore this and any other value. Future
	extensions to this protocol may specify other data to send instead of		extensions to this protocol may specify other data to send instead of
	an empty OCTET STRING.		an empty OCTET STRING.
	4. Security Considerations		4. Security Considerations
			The symmetric reply key size and Diffie-Hellman field size or RSA
			modulus size should be chosen so as to provide sufficient
			cryptographic security [RFC3766].
			When MODP Diffie-Hellman is used, the exponents should have at least
			twice as many bits as the symmetric keys that will be derived from
			them [ODL99].
	PKINIT raises certain security considerations beyond those that can		PKINIT raises certain security considerations beyond those that can
	be regulated strictly in protocol definitions. We will address them		be regulated strictly in protocol definitions. We will address them
	in this section.		in this section.
	PKINIT extends the cross-realm model to the public-key		PKINIT extends the cross-realm model to the public-key
	infrastructure. Users of PKINIT must understand security policies		infrastructure. Users of PKINIT must understand security policies
	and procedures appropriate to the use of Public Key Infrastructures		and procedures appropriate to the use of Public Key Infrastructures
	[RFC3280].		[RFC3280].
	Standard Kerberos allows the possibility of interactions between		Standard Kerberos allows the possibility of interactions between
	cryptosystems of varying strengths; this document adds interactions		cryptosystems of varying strengths; this document adds interactions
	with public-key cryptosystems to Kerberos. Some administrative		with public-key cryptosystems to Kerberos. Some administrative
	policies may allow the use of relatively weak public keys. Using		policies may allow the use of relatively weak public keys. Using
	such keys to wrap data encrypted under stronger conventional		such keys to wrap data encrypted under stronger conventional
	cryptosystems may be inappropriate.		cryptosystems may be inappropriate.
	PKINIT requires keys for symmetric cryptosystems to be generated.		PKINIT requires keys for symmetric cryptosystems to be generated.
	Some such systems contain "weak" keys. For recommendations regarding		Some such systems contain "weak" keys. For recommendations regarding
	these weak keys, see [CLAR].		these weak keys, see [RFC4120].
	PKINIT allows the use of the same RSA key pair for encryption and		PKINIT allows the use of the same RSA key pair for encryption and
	signing when doing RSA encryption based key delivery. This is not		signing when doing RSA encryption based key delivery. This is not
	recommended usage of RSA keys [RFC3447], by using DH based key		recommended usage of RSA keys [RFC3447], by using DH based key
	delivery this is avoided.		delivery this is avoided.
	Care should be taken in how certificates are chosen for the purposes		Care should be taken in how certificates are chosen for the purposes
	of authentication using PKINIT. Some local policies may require that		of authentication using PKINIT. Some local policies may require that
	key escrow be used for certain certificate types. Deployers of		key escrow be used for certain certificate types. Deployers of
	PKINIT should be aware of the implications of using certificates that		PKINIT should be aware of the implications of using certificates that
	skipping to change at page 22, line 48 ¶		skipping to change at page 23, line 21 ¶
	been invaluable.		been invaluable.
	6. IANA Considerations		6. IANA Considerations
	This document has no actions for IANA.		This document has no actions for IANA.
	7. References		7. References
	7.1 Normative References		7.1 Normative References
	[CLAR] RFC-Editor: To be replaced by RFC number for draft-ietf-
	krb-wg-kerberos-clarifications. Work in Progress.
	[IEEE1363]		[IEEE1363]
	IEEE, "Standard Specifications for Public Key		IEEE, "Standard Specifications for Public Key
	Cryptography", IEEE 1363, 2000.		Cryptography", IEEE 1363, 2000.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC2412] Orman, H., "The OAKLEY Key Determination Protocol",		[RFC2412] Orman, H., "The OAKLEY Key Determination Protocol",
	RFC 2412, November 1998.		RFC 2412, November 1998.
	skipping to change at page 24, line 8 ¶		skipping to change at page 24, line 24 ¶
	[RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)",		[RFC3852] Housley, R., "Cryptographic Message Syntax (CMS)",
	RFC 3852, July 2004.		RFC 3852, July 2004.
	[RFC3961] Raeburn, K., "Encryption and Checksum Specifications for		[RFC3961] Raeburn, K., "Encryption and Checksum Specifications for
	Kerberos 5", RFC 3961, February 2005.		Kerberos 5", RFC 3961, February 2005.
	[RFC3962] Raeburn, K., "Advanced Encryption Standard (AES)		[RFC3962] Raeburn, K., "Advanced Encryption Standard (AES)
	Encryption for Kerberos 5", RFC 3962, February 2005.		Encryption for Kerberos 5", RFC 3962, February 2005.
			[RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
			Kerberos Network Authentication Service (V5)", RFC 4120,
			July 2005.
			[RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos
			Version 5 Generic Security Service Application Program
			Interface (GSS-API) Mechanism: Version 2", RFC 4121,
			July 2005.
	[X.509-97] ITU-T. Recommendation X.509: The Directory - Authentication		[X.509-97] ITU-T. Recommendation X.509: The Directory - Authentication
	Framework. 1997.		Framework. 1997.
	[X690] ASN.1 encoding rules: Specification of Basic Encoding		[X690] ASN.1 encoding rules: Specification of Basic Encoding
	Rules (BER), Canonical Encoding Rules (CER) and		Rules (BER), Canonical Encoding Rules (CER) and
	Distinguished Encoding Rules (DER), ITU-T Recommendation		Distinguished Encoding Rules (DER), ITU-T Recommendation
	X.690 (1997) | ISO/IEC International Standard		X.690 (1997) | ISO/IEC International Standard
	8825-1:1998.		8825-1:1998.
	7.2 Informative References		7.2 Informative References
	skipping to change at page 25, line 4 ¶		skipping to change at page 25, line 27 ¶
	Larry Zhu		Larry Zhu
	Microsoft Corporation		Microsoft Corporation
	One Microsoft Way		One Microsoft Way
	Redmond, WA 98052		Redmond, WA 98052
	US		US
	Email: lzhu@microsoft.com		Email: lzhu@microsoft.com
	Appendix A. PKINIT ASN.1 Module		Appendix A. PKINIT ASN.1 Module
	KerberosV5-PK-INIT-SPEC {		KerberosV5-PK-INIT-SPEC {
	iso(1) identified-organization(3) dod(6) internet(1)		iso(1) identified-organization(3) dod(6) internet(1)
	security(5) kerberosV5(2) modules(4) pkinit(5)		security(5) kerberosV5(2) modules(4) pkinit(5)
	} DEFINITIONS EXPLICIT TAGS ::= BEGIN		} DEFINITIONS EXPLICIT TAGS ::= BEGIN
	IMPORTS		IMPORTS
	SubjectPublicKeyInfo, AlgorithmIdentifier		SubjectPublicKeyInfo, AlgorithmIdentifier
	FROM PKIX1Explicit88 { iso (1)		FROM PKIX1Explicit88 { iso (1)
	identified-organization (3) dod (6) internet (1)		identified-organization (3) dod (6) internet (1)
	security (5) mechanisms (5) pkix (7) id-mod (0)		security (5) mechanisms (5) pkix (7) id-mod (0)
	id-pkix1-explicit (18) }		id-pkix1-explicit (18) }
	-- As defined in RFC 3280.		-- As defined in RFC 3280.
	DomainParameters, EcpkParameters		DomainParameters
	FROM PKIX1Algorithms88 { iso(1)		FROM PKIX1Algorithms88 { iso(1)
	identified-organization(3) dod(6)		identified-organization(3) dod(6)
	internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)		internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
	id-mod-pkix1-algorithms(17) }		id-mod-pkix1-algorithms(17) }
	-- As defined in RFC 3279.		-- As defined in RFC 3279.
	KerberosTime, TYPED-DATA, PrincipalName, Realm, EncryptionKey		KerberosTime, TYPED-DATA, PrincipalName, Realm, EncryptionKey
	FROM KerberosV5Spec2 { iso(1) identified-organization(3)		FROM KerberosV5Spec2 { iso(1) identified-organization(3)
	dod(6) internet(1) security(5) kerberosV5(2)		dod(6) internet(1) security(5) kerberosV5(2)
	modules(4) krb5spec2(2) } ;		modules(4) krb5spec2(2) } ;
	skipping to change at page 26, line 4 ¶		skipping to change at page 26, line 30 ¶
	ad-initial-verified-cas INTEGER ::= 9		ad-initial-verified-cas INTEGER ::= 9
	td-trusted-certifiers INTEGER ::= 104		td-trusted-certifiers INTEGER ::= 104
	td-invalid-certificates INTEGER ::= 105		td-invalid-certificates INTEGER ::= 105
	td-dh-parameters INTEGER ::= 109		td-dh-parameters INTEGER ::= 109
	PA-PK-AS-REQ ::= SEQUENCE {		PA-PK-AS-REQ ::= SEQUENCE {
	signedAuthPack [0] IMPLICIT OCTET STRING,		signedAuthPack [0] IMPLICIT OCTET STRING,
	-- Contains a CMS type ContentInfo encoded		-- Contains a CMS type ContentInfo encoded
	-- according to [RFC3852].		-- according to [RFC3852].
	-- The contentType field of the type ContentInfo		-- The contentType field of the type ContentInfo
	-- is id-signedData (1.2.840.113549.1.7.2),		-- is id-signedData (1.2.840.113549.1.7.2),
	-- and the content field is a SignedData.		-- and the content field is a SignedData.
	-- The eContentType field for the type SignedData is		-- The eContentType field for the type SignedData is
	-- id-pkauthdata (1.3.6.1.5.2.3.1), and the		-- id-pkauthdata (1.3.6.1.5.2.3.1), and the
	-- eContent field contains the DER encoding of the		-- eContent field contains the DER encoding of the
	-- type AuthPack.		-- type AuthPack.
	-- AuthPack is defined below.		-- AuthPack is defined below.
	trustedCertifiers [1] SEQUENCE OF TrustedCA OPTIONAL,		trustedCertifiers [1] SEQUENCE OF
			ExternalPrincipalIdentifier OPTIONAL,
	-- A list of CAs, trusted by the client, that can		-- A list of CAs, trusted by the client, that can
	-- be used to certify the KDC.		-- be used to certify the KDC.
	-- Each TrustedCA identifies a CA or a CA		-- Each ExternalPrincipalIdentifier identifies a CA
	-- certificate (thereby its public key).		-- or a CA certificate (thereby its public key).
	-- The information contained in the		-- The information contained in the
	-- trustedCertifiers SHOULD be used by the KDC as		-- trustedCertifiers SHOULD be used by the KDC as
	-- hints to guide its selection of an appropriate		-- hints to guide its selection of an appropriate
	-- certificate chain to return to the client.		-- certificate chain to return to the client.
	kdcPkId [2] IMPLICIT OCTET STRING		kdcPkId [2] IMPLICIT OCTET STRING
	OPTIONAL,		OPTIONAL,
	-- Contains a CMS type SignerIdentifier encoded		-- Contains a CMS type SignerIdentifier encoded
	-- according to [RFC3852].		-- according to [RFC3852].
	-- Identifies, if present, a particular KDC		-- Identifies, if present, a particular KDC
	-- public key that the client already has.		-- public key that the client already has.
	...		...
	}		}
	DHNonce ::= OCTET STRING		DHNonce ::= OCTET STRING
	TrustedCA ::= SEQUENCE {		ExternalPrincipalIdentifier ::= SEQUENCE {
	caName [0] IMPLICIT OCTET STRING,		subjectName [0] IMPLICIT OCTET STRING OPTIONAL,
	-- Contains a PKIX type Name encoded according to		-- Contains a PKIX type Name encoded according to
	-- [RFC3280].		-- [RFC3280].
	-- Identifies a CA by the CA's distinguished subject		-- Identifies the certificate subject by the
	-- name.		-- distinguished subject name.
	certificateSerialNumber [1] INTEGER OPTIONAL,		-- REQUIRED when there is a distinguished subject
	-- Specifies the CA certificate's serial number.		-- name present in the certificate.
	-- The defintion of the certificate serial number		issuerAndSerialNumber [1] IMPLICIT OCTET STRING OPTIONAL,
	-- is taken from X.509 [X.509-97].		-- Contains a CMS type IssuerAndSerialNumber encoded
	subjectKeyIdentifier [2] OCTET STRING OPTIONAL,		-- according to [RFC3852].
	-- Identifies the CA's public key by a key		-- Identifies a certificate of the subject.
			-- REQUIRED for TD-INVALID-CERTIFICATES and
			-- TD-TRUSTED-CERTIFIERS.
			subjectKeyIdentifier [2] IMPLICIT OCTET STRING OPTIONAL,
			-- Identifies the subject's public key by a key
	-- identifier. When an X.509 certificate is		-- identifier. When an X.509 certificate is
	-- referenced, this key identifier matches the X.509		-- referenced, this key identifier matches the X.509
	-- subjectKeyIdentifier extension value. When other		-- subjectKeyIdentifier extension value. When other
	-- certificate formats are referenced, the documents		-- certificate formats are referenced, the documents
	-- that specify the certificate format and their use		-- that specify the certificate format and their use
	-- with the CMS must include details on matching the		-- with the CMS must include details on matching the
	-- key identifier to the appropriate certificate		-- key identifier to the appropriate certificate
	-- field.		-- field.
			-- RECOMMENDED for TD-TRUSTED-CERTIFIERS.
	...		...
	}		}
	AuthPack ::= SEQUENCE {		AuthPack ::= SEQUENCE {
	pkAuthenticator [0] PKAuthenticator,		pkAuthenticator [0] PKAuthenticator,
	clientPublicValue [1] SubjectPublicKeyInfo OPTIONAL,		clientPublicValue [1] SubjectPublicKeyInfo OPTIONAL,
	-- Type SubjectPublicKeyInfo is defined in		-- Type SubjectPublicKeyInfo is defined in
	-- [RFC3280].		-- [RFC3280].
	-- Specifies Diffie-Hellman domain parameters		-- Specifies Diffie-Hellman domain parameters
	-- and the client's public key value [IEEE1363].		-- and the client's public key value [IEEE1363].
	skipping to change at page 27, line 36 ¶		skipping to change at page 28, line 19 ¶
	clientDHNonce [3] DHNonce OPTIONAL,		clientDHNonce [3] DHNonce OPTIONAL,
	-- Present only if the client indicates that it		-- Present only if the client indicates that it
	-- wishes to reuse DH keys or to allow the KDC to		-- wishes to reuse DH keys or to allow the KDC to
	-- do so.		-- do so.
	...		...
	}		}
	PKAuthenticator ::= SEQUENCE {		PKAuthenticator ::= SEQUENCE {
	cusec [0] INTEGER (0..999999),		cusec [0] INTEGER (0..999999),
	ctime [1] KerberosTime,		ctime [1] KerberosTime,
	-- cusec and ctime are used as in [CLAR], for replay		-- cusec and ctime are used as in [RFC4120], for
	-- prevention.		-- replay prevention.
	nonce [2] INTEGER (0..4294967295),		nonce [2] INTEGER (0..4294967295),
	-- Chosen randomly; This nonce does not need to		-- Chosen randomly; This nonce does not need to
	-- match with the nonce in the KDC-REQ-BODY.		-- match with the nonce in the KDC-REQ-BODY.
	paChecksum [3] OCTET STRING,		paChecksum [3] OCTET STRING,
	-- Contains the SHA1 checksum, performed over		-- Contains the SHA1 checksum, performed over
	-- KDC-REQ-BODY.		-- KDC-REQ-BODY.
	...		...
	}		}
	TD-TRUSTED-CERTIFIERS ::= SEQUENCE OF TrustedCA		TD-TRUSTED-CERTIFIERS ::= SEQUENCE OF
			ExternalPrincipalIdentifier
	-- Identifies a list of CAs trusted by the KDC.		-- Identifies a list of CAs trusted by the KDC.
	-- Each TrustedCA identifies a CA or a CA		-- Each ExternalPrincipalIdentifier identifies a CA
	-- certificate (thereby its public key).		-- or a CA certificate (thereby its public key).
	TD-INVALID-CERTIFICATES ::= SEQUENCE OF OCTET STRING		TD-INVALID-CERTIFICATES ::= SEQUENCE OF
	-- Each OCTET STRING contains a CMS type		ExternalPrincipalIdentifier
	-- IssuerAndSerialNumber encoded according to		-- Each ExternalPrincipalIdentifier identifies a
	-- [RFC3852].
	-- Each IssuerAndSerialNumber identifies a
	-- certificate (sent by the client) with an invalid		-- certificate (sent by the client) with an invalid
	-- signature.		-- signature.
	KRB5PrincipalName ::= SEQUENCE {		KRB5PrincipalName ::= SEQUENCE {
	realm [0] Realm,		realm [0] Realm,
	principalName [1] PrincipalName		principalName [1] PrincipalName
	}		}
	AD-INITIAL-VERIFIED-CAS ::= SEQUENCE OF TrustedCA		AD-INITIAL-VERIFIED-CAS ::= SEQUENCE OF
			ExternalPrincipalIdentifier
	-- Identifies the certification path based on which		-- Identifies the certification path based on which
	-- the client certificate was validated.		-- the client certificate was validated.
	-- Each TrustedCA identifies a CA or a CA		-- Each ExternalPrincipalIdentifier identifies a CA
	-- certificate (thereby its public key).		-- or a CA certificate (thereby its public key).
	PA-PK-AS-REP ::= CHOICE {		PA-PK-AS-REP ::= CHOICE {
	dhInfo [0] DHRepInfo,		dhInfo [0] DHRepInfo,
	-- Selected when Diffie-Hellman key exchange is		-- Selected when Diffie-Hellman key exchange is
	-- used.		-- used.
	encKeyPack [1] IMPLICIT OCTET STRING,		encKeyPack [1] IMPLICIT OCTET STRING,
	-- Selected when public key encryption is used.		-- Selected when public key encryption is used.
	-- Contains a CMS type ContentInfo encoded		-- Contains a CMS type ContentInfo encoded
	-- according to [RFC3852].		-- according to [RFC3852].
	-- The contentType field of the type ContentInfo is		-- The contentType field of the type ContentInfo is
	skipping to change at page 29, line 37 ¶		skipping to change at page 30, line 19 ¶
	-- present if and only if DH keys are reused. If		-- present if and only if DH keys are reused. If
	-- this field is omitted then the serverDHNonce		-- this field is omitted then the serverDHNonce
	-- field MUST also be omitted.		-- field MUST also be omitted.
	...		...
	}		}
	ReplyKeyPack ::= SEQUENCE {		ReplyKeyPack ::= SEQUENCE {
	replyKey [0] EncryptionKey,		replyKey [0] EncryptionKey,
	-- Contains the session key used to encrypt the		-- Contains the session key used to encrypt the
	-- enc-part field in the AS-REP.		-- enc-part field in the AS-REP.
	nonce [1] INTEGER (0..4294967295),		asChecksum [1] Checksum,
	-- Contains the nonce in the PKAuthenticator of the		-- Contains the checksum of the AS-REQ
	-- request.		-- corresponding to the containing AS-REP.
			-- The checksum is performed over the type AS-REQ.
			-- The protocol key [RFC3961] of the checksum is the
			-- replyKey and the key usage number is 6.
			-- If the replyKey's enctype is "newer" [RFC4120]
			-- [RFC4121], the checksum is the required
			-- checksum operation [RFC3961] for that enctype.
			-- The client MUST verify this checksum upon receipt
			-- of the AS-REP.
	...		...
	}		}
	TD-DH-PARAMETERS ::= SEQUENCE OF AlgorithmIdentifier		TD-DH-PARAMETERS ::= SEQUENCE OF AlgorithmIdentifier
	-- Each AlgorithmIdentifier specifies a set of		-- Each AlgorithmIdentifier specifies a set of
	-- Diffie-Hellman domain parameters [IEEE1363].		-- Diffie-Hellman domain parameters [IEEE1363].
	-- This list is in decreasing preference order.		-- This list is in decreasing preference order.
	END		END
	Intellectual Property Statement		Intellectual Property Statement
End of changes. 70 change blocks.
	127 lines changed or deleted		168 lines changed or added
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