< draft-ietf-ipsec-isakmp-03.txt		draft-ietf-ipsec-isakmp-04.txt >
	IPSEC Working Group Douglas Maughan, Mark Schertler		IPSEC Working Group Douglas Maughan, Mark Schertler
	INTERNET-DRAFT National Security Agency		INTERNET-DRAFT National Security Agency
	draft-ietf-ipsec-isakmp-03.txt, .ps November 21, 1995		draft-ietf-ipsec-isakmp-04.txt, .ps February 21, 1996
	Internet Security Association and Key Management Protocol (ISAKMP)		Internet Security Association and Key Management Protocol (ISAKMP)
	Abstract		Abstract
	This memo describes a protocol utilizing security concepts		This memo describes a protocol utilizing security concepts
	necessary for establishing Security Associations (SA) and crypto-		necessary for establishing Security Associations (SA) and crypto-
	graphic keys in an Internet environment. A Security Association		graphic keys in an Internet environment. A Security Association
	protocol that negotiates, establishes, modifies and deletes		protocol that negotiates, establishes, modifies and deletes
	Security Associations and their attributes is required for an		Security Associations and their attributes is required for an
	skipping to change at page 3, line 14 ¶		skipping to change at page 3, line 14 ¶
	Contents		Contents
	1 Introduction 5		1 Introduction 5
	1.1 Authentication . . . . . . . . . . . . . . . . . . . . . . . . . 6		1.1 Authentication . . . . . . . . . . . . . . . . . . . . . . . . . 6
	1.1.1Certificate Authorities . . . . . . . . . . . . . . . . . . . 6		1.1.1Certificate Authorities . . . . . . . . . . . . . . . . . . . 6
	1.1.2Entity Naming . . . . . . . . . . . . . . . . . . . . . . . . 7		1.1.2Entity Naming . . . . . . . . . . . . . . . . . . . . . . . . 7
	1.1.3ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 7		1.1.3ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 7
	1.2 Security Associations and Management . . . . . . . . . . . . . . 8		1.2 Security Associations and Management . . . . . . . . . . . . . . 8
	1.2.1Security Associations and Registration . . . . . . . . . . . . 8		1.2.1Security Associations and Registration . . . . . . . . . . . . 8
	1.2.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 8		1.2.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 9
	1.3 Public Key Cryptography . . . . . . . . . . . . . . . . . . . . . 9		1.3 Public Key Cryptography . . . . . . . . . . . . . . . . . . . . . 9
	1.3.1Key Exchange Properties . . . . . . . . . . . . . . . . . . . 9		1.3.1Key Exchange Properties . . . . . . . . . . . . . . . . . . . 9
	1.3.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 11		1.3.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 11
	1.4 ISAKMP Protection . . . . . . . . . . . . . . . . . . . . . . . . 11		1.4 ISAKMP Protection . . . . . . . . . . . . . . . . . . . . . . . . 11
	1.4.1Anti-Clogging (Denial of Service) . . . . . . . . . . . . . . 11		1.4.1Anti-Clogging (Denial of Service) . . . . . . . . . . . . . . 11
	1.4.2Connection Hijacking . . . . . . . . . . . . . . . . . . . . . 11		1.4.2Connection Hijacking . . . . . . . . . . . . . . . . . . . . . 11
	1.4.3Man-in-the-Middle Attacks . . . . . . . . . . . . . . . . . . 11		1.4.3Man-in-the-Middle Attacks . . . . . . . . . . . . . . . . . . 12
	1.5 Multicast Communications . . . . . . . . . . . . . . . . . . . . 12		1.5 Multicast Communications . . . . . . . . . . . . . . . . . . . . 12
	2 Description of the Protocol 12		2 Description of the Protocol 13
	2.1 ISAKMP Header Format . . . . . . . . . . . . . . . . . . . . . . 13		2.1 ISAKMP Architecture . . . . . . . . . . . . . . . . . . . . . . . 13
	2.1.1General Message Processing . . . . . . . . . . . . . . . . . . 15		2.2 ISAKMP Packet Exchanges . . . . . . . . . . . . . . . . . . . . . 14
	2.2 ISAKMP Packet Exchanges . . . . . . . . . . . . . . . . . . . . . 17		2.2.1Base Exchange . . . . . . . . . . . . . . . . . . . . . . . . 14
	2.2.1Base Exchange . . . . . . . . . . . . . . . . . . . . . . . . 17		2.2.2Identity Protection Exchange . . . . . . . . . . . . . . . . . 14
	2.2.2Identity Protection Exchange . . . . . . . . . . . . . . . . . 17		2.2.3Authentication Only Exchange . . . . . . . . . . . . . . . . . 15
	2.2.3Authentication Only Exchange . . . . . . . . . . . . . . . . . 18		2.3 ISAKMP Details . . . . . . . . . . . . . . . . . . . . . . . . . 16
	2.3 ISAKMP Details . . . . . . . . . . . . . . . . . . . . . . . . . 19		2.3.1Basic ISAKMP Concepts . . . . . . . . . . . . . . . . . . . . 16
	2.3.1Security Association Attributes . . . . . . . . . . . . . . . 19		2.3.2ISAKMP Header Format . . . . . . . . . . . . . . . . . . . . . 17
	2.3.2Transport Protocol . . . . . . . . . . . . . . . . . . . . . . 21		2.3.3SPI Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 20
	2.3.3RESERVED Fields . . . . . . . . . . . . . . . . . . . . . . . 21		2.3.4General Message Processing . . . . . . . . . . . . . . . . . . 21
	2.3.4Anti-Clogging Token (``Cookie'') Creation . . . . . . . . . . 21		2.3.5Transport Protocol . . . . . . . . . . . . . . . . . . . . . . 23
	2.3.5SA Flags Field . . . . . . . . . . . . . . . . . . . . . . . . 22		2.3.6RESERVED Fields . . . . . . . . . . . . . . . . . . . . . . . 23
	3 Security Association Establishment 22		2.3.7Anti-Clogging Token (``Cookie'') Creation . . . . . . . . . . 23
	3.1 Security Association Initialization . . . . . . . . . . . . . . . 22		3 Security Association Establishment 25
	3.1.1SA Initialization Procedures . . . . . . . . . . . . . . . . . 24		3.1 Security Association Initialization . . . . . . . . . . . . . . . 25
	3.2 Authentication and Key Exchange . . . . . . . . . . . . . . . . . 25		3.1.1SA Initialization Procedures . . . . . . . . . . . . . . . . . 26
	3.2.1Authentication Payload Format . . . . . . . . . . . . . . . . 26		3.2 Authentication and Key Exchange . . . . . . . . . . . . . . . . . 28
	3.2.2Key Exchange Payload Format . . . . . . . . . . . . . . . . . 28		3.2.1Authentication Payload Format . . . . . . . . . . . . . . . . 28
	3.2.3Authentication and Key Exchange Procedures . . . . . . . . . . 29		3.2.2Key Exchange Payload Format . . . . . . . . . . . . . . . . . 29
	3.3 Security Association Negotiation . . . . . . . . . . . . . . . . 30		3.2.3Authentication and Key Exchange Procedures . . . . . . . . . . 30
	3.3.1SA Negotiation Procedures . . . . . . . . . . . . . . . . . . 31		3.3 Security Association Negotiation . . . . . . . . . . . . . . . . 32
	3.4 SA Negotiation Conclusion . . . . . . . . . . . . . . . . . . . . 34		3.3.1SA Negotiation Procedures . . . . . . . . . . . . . . . . . . 32
	3.4.1SA Negotiation Conclusion Procedures . . . . . . . . . . . . . 34
	4 Security Association Modification 36
	4.1 Modification Procedures . . . . . . . . . . . . . . . . . . . . . 36
	5 Security Association Deletion 36
	5.1 Deletion Procedures . . . . . . . . . . . . . . . . . . . . . . . 37
	6 Notification Message 39		4 Security Association Modification 38
	6.1 Notification Procedures . . . . . . . . . . . . . . . . . . . . . 40		4.1 Modification Procedures . . . . . . . . . . . . . . . . . . . . . 38
			5 Security Association Deletion 38
			5.1 Deletion Procedures . . . . . . . . . . . . . . . . . . . . . . . 39
	7 Conclusions 41		6 Notification Message 41
			6.1 Notify Message Types . . . . . . . . . . . . . . . . . . . . . . 42
			6.2 Notification Procedures . . . . . . . . . . . . . . . . . . . . . 42
	A ISAKMP Scenarios 43		7 Conclusions 44
	A.1 Initial ISAKMP Daemon Scenerio . . . . . . . . . . . . . . . . . 43
	A.2 Virtual Private Network Scenario . . . . . . . . . . . . . . . . 44
	B Security Association Attributes 47
	C Security Association Examples 51		A IP Security DOI 45
	C.1 ISAKMP SA Definition . . . . . . . . . . . . . . . . . . . . . . 51		A.1 IP Security Proposal Formats . . . . . . . . . . . . . . . . . . 45
	C.1.1ISAKMP SA Examples . . . . . . . . . . . . . . . . . . . . . . 52		A.2 ESP SA and AH SA Proposals . . . . . . . . . . . . . . . . . . . 48
	C.2 ESP SA and AH SA Definitions . . . . . . . . . . . . . . . . . . 53		A.3 Oakley Proposal . . . . . . . . . . . . . . . . . . . . . . . . . 51
	C.2.1ESP and AH SA Examples . . . . . . . . . . . . . . . . . . . . 54		A.4 Attribute Class Assigned Numbers . . . . . . . . . . . . . . . . 53
	C.2.2Fortezza SA Examples . . . . . . . . . . . . . . . . . . . . . 55		A.5 Attribute Value Assigned Numbers . . . . . . . . . . . . . . . . 54
			A.5.1Sensitivity Level Assigned Numbers . . . . . . . . . . . . . . 54
			A.5.2Key Exchange Identifiers (KEI) Assigned Numbers . . . . . . . 54
			A.5.3Encryption Transform Assigned Numbers . . . . . . . . . . . . 54
			B ISAKMP Scenarios 55
			B.1 Oakley Scenario . . . . . . . . . . . . . . . . . . . . . . . . . 55
			B.2 Virtual Private Network Scenario . . . . . . . . . . . . . . . . 57
			C Security Association Attributes 60
	1 Introduction		1 Introduction
	This document describes an Internet Security Association and Key Manage-		This document describes an Internet Security Association and Key Manage-
	ment Protocol (ISAKMP). ISAKMP combines the security concepts of authen-		ment Protocol (ISAKMP). ISAKMP combines the security concepts of authen-
	tication, key management, and security associations to establish the re-		tication, key management, and security associations to establish the re-
	quired security for government, commercial, and private communications on		quired security for government, commercial, and private communications on
	the Internet. ISAKMP extends the assertion in [DOW92] that authentica-		the Internet. ISAKMP extends the assertion in [DOW92] that authentica-
	tion and key exchanges must be combined for better security to include se-		tion and key exchanges must be combined for better security to include se-
	curity association exchanges. The security required for communications		curity association exchanges. The security required for communications
	depends on the individual network configurations and environments. Orga-		depends on the individual network configurations and environments. Orga-
	skipping to change at page 6, line 30 ¶		skipping to change at page 6, line 30 ¶
	Digital signatures, such as the Digital Signature Standard (DSS) and the		Digital signatures, such as the Digital Signature Standard (DSS) and the
	Rivest-Shamir-Adleman (RSA) signature, are public key based strong authen-		Rivest-Shamir-Adleman (RSA) signature, are public key based strong authen-
	tication mechanisms. When using digital signatures each entity requires a		tication mechanisms. When using digital signatures each entity requires a
	public and a private key. Certificates are an essential part of a digital		public and a private key. Certificates are an essential part of a digital
	signature authentication mechanism. Certificates bind a specific enti-		signature authentication mechanism. Certificates bind a specific enti-
	ties identity (be it host, network, user, or application) to its public		ties identity (be it host, network, user, or application) to its public
	keys and possibly other security-related information such as privileges,		keys and possibly other security-related information such as privileges,
	clearances, and compartments. Authentication based on digital signatures		clearances, and compartments. Authentication based on digital signatures
	requires a trusted third party or certificate authority to create, sign		requires a trusted third party or certificate authority to create, sign
	and properly distribute certificates. For more detailed information on		and properly distribute certificates. For more detailed information on
	digital signatures, such as DSS and RSA, and certificates see [Schn94].		digital signatures, such as DSS and RSA, and certificates see [Schneier].
	1.1.1 Certificate Authorities		1.1.1 Certificate Authorities
	Certificates require an infrastructure for generation, verification, man-		Certificates require an infrastructure for generation, verification, man-
	agement and distribution. The Internet Policy Registration Authority		agement and distribution. The Internet Policy Registration Authority
	(IPRA) [RFC-1422] has been established to direct this infrastructure for		(IPRA) [RFC-1422] has been established to direct this infrastructure for
	the IETF. The IPRA certifies Policy Certification Authorities (PCA). PCAs		the IETF. The IPRA certifies Policy Certification Authorities (PCA). PCAs
	control Certificate Authorities (CA) which certify users and subordinate		control Certificate Authorities (CA) which certify users and subordi-
	entities. Current certificate related work includes the Domain Name Sys-		nate entities. Current certificate related work includes the Domain Name
	tem (DNS) Security Extensions [EK94] which will provide signed entity keys		System (DNS) Security Extensions [DNSSEC] which will provide signed en-
	in the DNS. The Public Key Infrastucture (PKIX) working group is speci-		tity keys in the DNS. The Public Key Infrastucture (PKIX) working group
	fying an Internet profile for X.509 certificates. There is also work go-		is specifying an Internet profile for X.509 certificates. There is also
	ing on in industry to develop X.500 Directory Services which would provide		work going on in industry to develop X.500 Directory Services which would
	X.509 certificates to users. The U.S. Post Office is developing a (CA)		provide X.509 certificates to users. The U.S. Post Office is developing
	hierarchy. The NIST Public Key Infrastructure Working Group has also been		a (CA) hierarchy. The NIST Public Key Infrastructure Working Group has
	doing work in this area. The DOD Multi Level Information System Security		also been doing work in this area. The DOD Multi Level Information System
	Initiative (MISSI) program has begun deploying a certificate infrastruc-		Security Initiative (MISSI) program has begun deploying a certificate in-
	ture for the U.S. Government. Alternatively, if no infrastructure exists,		frastructure for the U.S. Government. Alternatively, if no infrastructure
	the PGP Web of Trust certificates can be used to provide user authentica-		exists, the PGP Web of Trust certificates can be used to provide user au-
	tion and privacy in a community of users who know and trust each other.		thentication and privacy in a community of users who know and trust each
			other.
	1.1.2 Entity Naming		1.1.2 Entity Naming
	An entity's name is its identity and is bound to its public keys in cer-		An entity's name is its identity and is bound to its public keys in cer-
	tificates. The CA MUST define the naming semantics for the certificates		tificates. The CA MUST define the naming semantics for the certificates
	it issues. See the UNINETT PCA Policy Statements [Berg] for an example		it issues. See the UNINETT PCA Policy Statements [Berge] for an example
	of how a CA defines its naming policy. When the certificate is verified,		of how a CA defines its naming policy. When the certificate is verified,
	the name is verified and that name will have meaning within the realm of		the name is verified and that name will have meaning within the realm of
	that CA. An example is the DNS security extensions which make DNS servers		that CA. An example is the DNS security extensions which make DNS servers
	CAs for the zones and nodes they serve. Resource records are provided for		CAs for the zones and nodes they serve. Resource records are provided for
	public keys and signatures on those keys. The names associatied with the		public keys and signatures on those keys. The names associatied with the
	keys are IP addresses and domain names which have meaning to entities ac-		keys are IP addresses and domain names which have meaning to entities ac-
	cessing the DNS for this information. A Web of Trust is another example.		cessing the DNS for this information. A Web of Trust is another example.
	When webs of trust are set up, names are bound with the public keys. In		When webs of trust are set up, names are bound with the public keys. In
	PGP the name is usaully the entities e-mail address which has meaning to		PGP the name is usaully the entities e-mail address which has meaning to
	those, and only those, who understand e-mail (Do MCI and AOL e-mail ad-		those, and only those, who understand e-mail. Another web of trust could
	dresses tell the casual e-mailer anything about identity?). Another web		use an entirely different naming scheme.
	could use an entirely different naming scheme.
	1.1.3 ISAKMP Requirements		1.1.3 ISAKMP Requirements
	Strong authentication MUST be provided on ISAKMP exchanges. Without being		Strong authentication MUST be provided on ISAKMP exchanges. Without being
	able to authenticate the entity at the other end, the Security Association		able to authenticate the entity at the other end, the Security Association
	(SA) and session key established are suspect. Without authentication you		(SA) and session key established are suspect. Without authentication you
	are unable to trust an entity's identification, this makes access control		are unable to trust an entity's identification, this makes access control
	questionable. Encryption (e.g. ESP) and integrity (e.g. AH) will pro-		questionable. Encryption (e.g. ESP) and integrity (e.g. AH) will pro-
	tect subsequent communications from passive eavesdroppers, but the SA and		tect subsequent communications from passive eavesdroppers, but the SA and
	key may be established with an adversary who performed an active man-in-		key may be established with an adversary who performed an active man-in-
	the-middle attack and is now stealing all your personnal data.		the-middle attack and is now stealing all your personnal data.
	A digital signature algorithm MUST be used within ISAKMP's authentication		A digital signature algorithm MUST be used within ISAKMP's authentication
	component. However, ISAKMP does not mandate a specific mechanism. ISAKMP		component. However, ISAKMP does not mandate a specific signature algo-
	allows an entity initiating communications to indicate which signature al-		rithm or certificate authority (CA). ISAKMP allows an entity initiating
	gorithms it supports. After selection of a common algorithm, the protocol		communications to indicate which CAs it supports. After selection of a
	provides the messages required to support the actual authentication ex-		CA, the protocol provides the messages required to support the actual au-
	change. As an example, if the DSA is selected as the signature algorithm,		thentication exchange. The protocol provides a facility for identifica-
	then the protocol provides a facility for identification of different cer-		tion of different certificate authorities, certificate types (e.g. X.509,
	tificate authorities, certificate types (e.g. X.509v1 certificates, PKCS		PKCS #7, PGP, DNS SIG and KEY records), and the exchange of the certifi-
	#7), and the exchange of the certificates identified.		cates identified.
	ISAKMP utilizes digital signatures, based on public cryptography, for au-		ISAKMP utilizes digital signatures, based on public cryptography, for au-
	thentication. There are other strong authentication systems available,		thentication. There are other strong authentication systems available,
	which could be specified as additional optional authentication mechanisms		which could be specified as additional optional authentication mechanisms
	for ISAKMP. Some of these authentication systems rely on a trusted third		for ISAKMP. Some of these authentication systems rely on a trusted third
	party called a key distribution center (KDC) to distribute secret session		party called a key distribution center (KDC) to distribute secret session
	keys. An example is Kerberos, where the trusted third party is the Ker-		keys. An example is Kerberos, where the trusted third party is the Ker-
	beros server, which holds secret keys for all clients and servers within		beros server, which holds secret keys for all clients and servers within
	it's network domain. A clients proof it holds it's secret key provides		it's network domain. A clients proof it holds it's secret key provides
	its authenticaton to a server.		its authenticaton to a server.
	skipping to change at page 8, line 23 ¶		skipping to change at page 8, line 25 ¶
	that describes how the entities will utilize security services to communi-		that describes how the entities will utilize security services to communi-
	cate securely. This relationship is represented by a set of information		cate securely. This relationship is represented by a set of information
	that can be considered a contract between the entities. The information		that can be considered a contract between the entities. The information
	must be agreed upon and shared between all the entities. Sometimes the		must be agreed upon and shared between all the entities. Sometimes the
	information alone is referred to as an SA, but this is just a physical in-		information alone is referred to as an SA, but this is just a physical in-
	stantiation of the existing relationship. The existence of this relation-		stantiation of the existing relationship. The existence of this relation-
	ship, represented by the information, is what provides the agreed upon se-		ship, represented by the information, is what provides the agreed upon se-
	curity information needed by entities to securely interoperate. All enti-		curity information needed by entities to securely interoperate. All enti-
	ties must adhere to the SA for secure communications to be possible. When		ties must adhere to the SA for secure communications to be possible. When
	accessing SA attributes, entities use a pointer or identifier refered to		accessing SA attributes, entities use a pointer or identifier refered to
	as the Security Parameter Index (SPI).		as the Security Parameter Index (SPI). See [RFC-1825] for details on IP
			Security SAs and SPIs definitions.
	1.2.1 Security Associations and Registration		1.2.1 Security Associations and Registration
	The SA attributes required and recommended for the IP Security (AH, ESP)		The SA attributes required and recommended for the IP Security (AH, ESP)
	are defined in [RFC-1825]. The attributes specified for an IP Security SA		are defined in [RFC-1825]. The attributes specified for an IP Security SA
	include, but are not limited to, authentication mechanism, cryptographic		include, but are not limited to, authentication mechanism, cryptographic
	algorithm, algorithm mode, key length, and Initialization Vector (IV).		algorithm, algorithm mode, key length, and Initialization Vector (IV).
	Other protocols that provide algorithm and mechanism independent security		Other protocols that provide algorithm and mechanism independent security
	MUST define their SA attributes requirements. The separation of ISAKMP		MUST define their SA attributes requirements. The separation of ISAKMP
	from a specific SA definition is important to ensure ISAKMP can establish		from a specific SA definition is important to ensure ISAKMP can establish
	SAs for all possible security protocols and applications.		SAs for all possible security protocols and applications.
	NOTE: See Appendix B for a discussion of SA attributes that should be con-		NOTE: See Appendix C for a discussion of SA attributes that should be con-
	sidered when defining a security protocol or application.		sidered when defining a security protocol or application.
	In order to facilitate easy identification of specific attributes (e.g.		In order to facilitate easy identification of specific attributes (e.g.
	a specific encryption algorithm) among different network entites the at-		a specific encryption algorithm) among different network entites the at-
	tributes must be assigned identifiers and these identifiers must be reg-		tributes must be assigned identifiers and these identifiers must be reg-
	istered by a central authority. The Internet Assigned Numbers Authority		istered by a central authority. The Internet Assigned Numbers Authority
	(IANA) provides this function for the Internet.		(IANA) provides this function for the Internet.
	1.2.2 ISAKMP Requirements		1.2.2 ISAKMP Requirements
	skipping to change at page 9, line 22 ¶		skipping to change at page 9, line 28 ¶
	tion for subsequent ISAKMP exchanges. It also indicates the authentica-		tion for subsequent ISAKMP exchanges. It also indicates the authentica-
	tion method and key exchange that will be performed as part of the ISAKMP		tion method and key exchange that will be performed as part of the ISAKMP
	protocol. If a basic set of security attributes is already in place on		protocol. If a basic set of security attributes is already in place on
	the communicating entities the initial ISAKMP exchange may be skipped and		the communicating entities the initial ISAKMP exchange may be skipped and
	the key and authentication exchanges issued directly. After the basic set		the key and authentication exchanges issued directly. After the basic set
	of security attributes has been agreed upon, initial identity authenti-		of security attributes has been agreed upon, initial identity authenti-
	cated, and required keys generated, another security attribute exchange		cated, and required keys generated, another security attribute exchange
	takes place to establish the complete SA which will be used for subsequent		takes place to establish the complete SA which will be used for subsequent
	communications by the entity that invoked ISAKMP. The basic set of SA at-		communications by the entity that invoked ISAKMP. The basic set of SA at-
	tributes that MUST be implemented to provide ISAKMP interoperability are		tributes that MUST be implemented to provide ISAKMP interoperability are
	defined in Appendix C. *These atributes will be moved to a separate docu-		defined in Appendix A. *These atributes will be moved to a separate docu-
	ment to maintain separation of protocol and attributes.*		ment to maintain separation of protocol and attributes.*
	1.3 Public Key Cryptography		1.3 Public Key Cryptography
	Public key cryptography is the most flexible, scalable, and efficient way		Public key cryptography is the most flexible, scalable, and efficient way
	for users to obtain the shared secrets and session keys needed to support		for users to obtain the shared secrets and session keys needed to support
	the large number of ways Internet users will interoperate. Many key gen-		the large number of ways Internet users will interoperate. Many key gen-
	eration algorithms, that have different properties, are available to users		eration algorithms, that have different properties, are available to users
	(see [DOW92] and [ANSI94]). Properties of key exchange protocols include		(see [DOW92] and [ANSI]). Properties of key exchange protocols include
	the key establishment method, authentication, symmetry, perfect forward		the key establishment method, authentication, symmetry, perfect forward
	secrecy, and back traffic protection.		secrecy, and back traffic protection.
	1.3.1 Key Exchange Properties		1.3.1 Key Exchange Properties
	Key Establishment (Key Generation / Key Transport) The two common methods		Key Establishment (Key Generation / Key Transport) The two common methods
	of using public key cryptography for key establishment are key transport		of using public key cryptography for key establishment are key transport
	and key generation. An example of key transport is the use of the RSA al-		and key generation. An example of key transport is the use of the RSA al-
	gorithm to encrypt a randomly generated session key (for encrypting subse-		gorithm to encrypt a randomly generated session key (for encrypting subse-
	quent communications) with the recipient's public key. The encrypted ran-		quent communications) with the recipient's public key. The encrypted ran-
	dom key is then sent to the recipient, who decrypts it using his private		dom key is then sent to the recipient, who decrypts it using his private
	key. At this point both sides have the same session key, however it was		key. At this point both sides have the same session key, however it was
	created based on input from only one side of the communications. The ben-		created based on input from only one side of the communications. The ben-
	efit of the key transport method is that it has less computational over-		efit of the key transport method is that it has less computational over-
	head then the following method. The Diffie-Hellman (D-H) algorithm illus-		head then the following method. The Diffie-Hellman (D-H) algorithm il-
	trates key generation using public key cryptography. The D-H algorithm is		lustrates key generation using public key cryptography. The D-H algorithm
	begun by two users exchanging public information. Each user then mathe-		is begun by two users exchanging public information. Each user then math-
	matically combines the other's public information along with their own se-		ematically combines the other's public information along with their own
	cret information to compute a shared secret value. This secret value can		secret information to compute a shared secret value. This secret value
	be used as a session key or as a key encryption key for encrypting a ran-		can be used as a session key or as a key encryption key for encrypting
	domly generated session key. This method generates a session key based on		a randomly generated session key. This method generates a session key
	public and secret information held by both users. The benefit of the D-H		based on public and secret information held by both users. The benefit
	algorithm is that the key used for encrypting messages is based on infor-		of the D-H algorithm is that the key used for encrypting messages is based
	mation held by both users. Assuming checks for weak values neither party		on information held by both users. Assuming checks for weak values nei-
	can force the session key to a predetermined value. Detailed descrip-		ther party can force the session key to a predetermined value. Detailed
	tions of these algorithms can be found in [Schn94]. There are a number		descriptions of these algorithms can be found in [Schneier]. There are a
	of variations on these two key generation schemes and these variations do		number of variations on these two key generation schemes and these varia-
	not necessarily interoperate.		tions do not necessarily interoperate.
	Key Exchange Authentication Key exchanges may be authenticated during the		Key Exchange Authentication Key exchanges may be authenticated during the
	protocol or after protocol completion. Authentication of the key exchange		protocol or after protocol completion. Authentication of the key exchange
	during the protocol is provide when each party provides proof it has the		during the protocol is provided when each party provides proof it has the
	secret session key before the end of the protocol. Proof can be provided		secret session key before the end of the protocol. Proof can be provided
	by encrypting known data in the secret session key during the protocol ex-		by encrypting known data in the secret session key during the protocol ex-
	change. Authentication after the protocol must occur in subsequent commu-		change. Authentication after the protocol must occur in subsequent commu-
	nications. Authentication during the protocol is preferred so subsequent		nications. Authentication during the protocol is preferred so subsequent
	communications are not initiated if the secret session key is not estab-		communications are not initiated if the secret session key is not estab-
	lished with the desired party.		lished with the desired party.
	Key Exchange Symmetry A key exchange provides symmetry if either party can		Key Exchange Symmetry A key exchange provides symmetry if either party can
	initiate the exchange and exchanged messages can cross in transit with-		initiate the exchange and exchanged messages can cross in transit with-
	out effecting the key that is generated. This is desirable so that com-		out effecting the key that is generated. This is desirable so that com-
	skipping to change at page 10, line 38 ¶		skipping to change at page 10, line 44 ¶
	the exchange. While key exchange symmetry is desirable, symmetry in the		the exchange. While key exchange symmetry is desirable, symmetry in the
	entire KMP may provide a vulnerablity to reflection attacks. The entire		entire KMP may provide a vulnerablity to reflection attacks. The entire
	ISAKMP SA establishment is asymetrical.		ISAKMP SA establishment is asymetrical.
	Back Traffic Protection / Perfect Forward Secrecy Perfect forward secrecy		Back Traffic Protection / Perfect Forward Secrecy Perfect forward secrecy
	is provided by a key exchange protocol if disclosure of long-term cryp-		is provided by a key exchange protocol if disclosure of long-term cryp-
	tographic keying material (e.g. public signature keys) does not compro-		tographic keying material (e.g. public signature keys) does not compro-
	mise previously generated keys. Back traffic protection is provided by		mise previously generated keys. Back traffic protection is provided by
	the independent generation of each key such that subsequent keys are not		the independent generation of each key such that subsequent keys are not
	dependent on any previous key. There is a subtle difference. Past ses-		dependent on any previous key. There is a subtle difference. Past ses-
	sion keys will NOT be obtainable is the long-term key is compromised in		sion keys will NOT be obtainable if the long-term key is compromised in
	perfect forward secrecy; Past session keys will NOT be obtainable if the		perfect forward secrecy; Past session keys will NOT be obtainable if the
	current session key is compromised in back traffic protecion.		current session key is compromised in back traffic protecion.
	The difficulty of numerical factoring of large numbers has proven that		The difficulty of numerical factoring of large numbers has proven that
	cryptographic keys can protect information for a considerable length of		cryptographic keys can protect information for a considerable length of
	time. However, this is based on the assumption that keys used for protec-		time. However, this is based on the assumption that keys used for protec-
	tion of communications are destroyed after use and not kept for any rea-		tion of communications are destroyed after use and not kept for any rea-
	son.		son.
	1.3.2 ISAKMP Requirements		1.3.2 ISAKMP Requirements
	skipping to change at page 11, line 22 ¶		skipping to change at page 11, line 23 ¶
	secrecy, back traffic protection, computational overhead, key escrow, and		secrecy, back traffic protection, computational overhead, key escrow, and
	key strength. Based on user requirements, ISAKMP allows an entity initi-		key strength. Based on user requirements, ISAKMP allows an entity initi-
	ating communications to indicate which key exchanges it supports. After		ating communications to indicate which key exchanges it supports. After
	selection of a key exchange, the protocol provides the messages required		selection of a key exchange, the protocol provides the messages required
	to support the actual key establishment.		to support the actual key establishment.
	1.4 ISAKMP Protection		1.4 ISAKMP Protection
	1.4.1 Anti-Clogging (Denial of Service)		1.4.1 Anti-Clogging (Denial of Service)
	Of the numerous security services available, protection against denial		Of the numerous security services available, protection against denial of
	of service always seems to be one of the most difficult to address. Phil		service always seems to be one of the most difficult to address. Phil
	Karn in his Internet-Draft [Karn95] has introduced a mechanism to provide		Karn in his Internet-Draft [Karn] has introduced a mechanism to provide
	a measure of denial of service protection through the use of a ``cookie''		a measure of denial of service protection through the use of a ``cookie''
	exchange. This anti-clogging token (ACT) is aimed at protecting the com-		exchange. This anti-clogging token (ACT) is aimed at protecting the com-
	puting resources from attack without spending excessive CPU resources to		puting resources from attack without spending excessive CPU resources to
	determine its authenticity. As described in [Karn95], an exchange prior		determine its authenticity. As described in [Karn], an exchange prior to
	to CPU-intensive public key operations can thwart some denial of service		CPU-intensive public key operations can thwart some denial of service at-
	attempts (e.g. simple flooding with bogus IP source addresses). As noted		tempts (e.g. simple flooding with bogus IP source addresses). As noted
	by Karn, absolute protection against denial of service is impossible, but		by Karn, absolute protection against denial of service is impossible, but
	this anti-clogging token provides a technique for making it easier to han-		this anti-clogging token provides a technique for making it easier to han-
	dle.		dle.
	1.4.2 Connection Hijacking		1.4.2 Connection Hijacking
	ISAKMP prevents connection hijacking by linking the authentication, key		ISAKMP prevents connection hijacking by linking the authentication, key
	exchange and security association exchanges. This linking prevent an at-		exchange and security association exchanges. This linking prevents an
	tacker from allowing the authentication to complete and then jumping in		attacker from allowing the authentication to complete and then jumping
	and impersonating one entity to the other during the key and security as-		in and impersonating one entity to the other during the key and security
	sociation exchanges.		association exchanges.
	1.4.3 Man-in-the-Middle Attacks		1.4.3 Man-in-the-Middle Attacks
	Man-in-the-Middle attacks include interception, insertion, deletion, and		Man-in-the-Middle attacks include interception, insertion, deletion, and
	modification of messages, reflecting messages back at the sender, re-		modification of messages, reflecting messages back at the sender, re-
	playing old messages and redirecting messages. ISAKMP features prevent		playing old messages and redirecting messages. ISAKMP features prevent
	these types of attacks from being successful. The linking of the ISAKMP		these types of attacks from being successful. The linking of the ISAKMP
	exchanges prevents the insertion of messages in the protocol exchange.		exchanges prevents the insertion of messages in the protocol exchange.
	The ISAKMP protocol state machine is defined so deleted messages will not		The ISAKMP protocol state machine is defined so deleted messages will not
	cause a partial SA to be created, the state machine will clear all state		cause a partial SA to be created, the state machine will clear all state
	skipping to change at page 12, line 26 ¶		skipping to change at page 12, line 32 ¶
	ing the appropriate party of this abnormality.		ing the appropriate party of this abnormality.
	1.5 Multicast Communications		1.5 Multicast Communications
	While future Internet communications will increasingly be of a multicast		While future Internet communications will increasingly be of a multicast
	nature, this document is presenting a security association and key man-		nature, this document is presenting a security association and key man-
	agement protocol from the unicast point of view. It is expected that mul-		agement protocol from the unicast point of view. It is expected that mul-
	ticast communications will require the same security services as unicast		ticast communications will require the same security services as unicast
	communications and may introduce the need for additional security ser-		communications and may introduce the need for additional security ser-
	vices. The issues of distributing SPIs for multicast traffic are pre-		vices. The issues of distributing SPIs for multicast traffic are pre-
	sented in [RFC-1825]. Upon agreement and implementation of a security		sented in [RFC-1825]. Multicast security issues are also discussed in
	association protocol for the Internet unicast environment, we fully intend		[BC]. Upon agreement and implementation of a security association pro-
	to examine any additional security requirements for multicast communica-		tocol for the Internet unicast environment, we fully intend to examine any
	tions. For an introduction to the issues related to multicast security		additional security requirements for multicast communications. For an in-
	consult the Internet Drafts, [Spar94a] and [Spar94b], describing Sparta's		troduction to the issues related to multicast security consult the Inter-
	research in this area.		net Drafts, [Spar94a] and [Spar94b], describing Sparta's research in this
			area.
	2 Description of the Protocol		2 Description of the Protocol
	The Internet Security Association and Key Management Protocol (ISAKMP) de-		The Internet Security Association and Key Management Protocol (ISAKMP) de-
	fines procedures and packet formats to establish, negotiate, modify and		fines procedures and packet formats to establish, negotiate, modify and
	delete Security Associations (SA). SAs contain all the information re-		delete Security Associations (SA). SAs contain all the information re-
	quired for execution of IP security services, such as the IP Authentica-		quired for execution of IP security services, such as the IP Authentica-
	tion Header (AH), the IP Encapsulating Security Payload (ESP), and routing		tion Header (AH), the IP Encapsulating Security Payload (ESP), and routing
	protocol authentication mechanisms. ISAKMP includes packet formats for		protocol authentication mechanisms. ISAKMP includes packet formats for
	exchanging key generation and authentication data. These formats provide		exchanging key generation and authentication data. These formats provide
	a consistent method of transferring key and authentication data that is		a consistent method of transferring key and authentication data that is
	independent of the key generation technique, encryption algorithm or au-		independent of the key generation technique, encryption algorithm or au-
	thentication mechanism.		thentication mechanism.
	The following sections contain the details of ISAKMP. Sections 2.1 through		2.1 ISAKMP Architecture
	2.3 cover details that are pertinent to the entire protocol. Sections 3
	through 6 define the establishment, modification, and deletion services,
	defined as exchanges, offered by the protocol. The appendices provide
	examples of SAs and key exchanges.
	2.1 ISAKMP Header Format		The following figure is a high level view of the placement of ISAKMP in a
			network architecture.
	ISAKMP has a fixed header format (shown in Figure 1) followed by a vari-		+-------------+ +--------------+
			! Negotiation ! Situation ! Application !
			! Server !<---- ! Process !
			+-------------+ ! +--------------+
			! ISAKMP ! ! ! Appl Protocol!
			+-------------+ ! SPI +--------------+
			! v !
			+---------------------------------------------+
			! Sockets !
			+---------------------------------------------+
			! Transport Protocol (TCP / UDP) !
			+---------------------------------------------+
			! IP !
			+---------------------------------------------+
			! Link Layer Protocol !
			+---------------------------------------------+
			Figure 1: ISAKMP Relationships
			The negotiation server is an application process which interfaces with the
			different policy databases (security, network access, cryptographic, au-
			thentication, etc.) that a system may require. It calls upon ISAKMP to
			deliver the data required to establish an SA and key and authenticate the
			exchange. The negotiation server can be invoked manually by a user or au-
			tomatically by an up-call from a security protocol when it requires an SA.
			The situation contains the identification and credential information re-
			quired by the negotiation server to make policy decisions. The negotia-
			tion server returns a SPI when an SA is established.
			2.2 ISAKMP Packet Exchanges
			The Exchange field in the ISAKMP header currently has three values de-
			fined: the base exchange, the identity protection exchange, and the au-
			thentication only exchange. These exchanges define the flow of the ISAKMP
			packets during SA establishment. The diagrams in 2.2.1, 2.2.2, and 2.2.3
			show the packet exchange ordering for each exchange type and provide ba-
			sic notes describing what has happened after each packet exchange. These
			exchanges are a high level summary of the packet flow, they do not show
			processing or error handling. Detailed connection establishment process-
			ing is defined in sections 3 through 6.
			2.2.1 Base Exchange
			Sections 3.1 through 3.3 describe the three basic phases: SA Initial-
			ization, Key Exchange and Authentication, and SA Negotiation, that com-
			prise the base exchange. The base exchange contains the minimum number of
			packet exchanges in order to reduce latency associated with SA establish-
			ment.
			Base Exchange
			___Initiator_____Direction____Responder_____ Note
			ISA_INIT_REQ =>
			<= ISA_INIT_RESP
			Basic SA selected
			ISA_AUTH&KE_REQ =>
			<= ISA_AUTH&KE_RESP
			Identity Verified
			Key Generated
			Encryption Begun
			ISA_NEG_REQ =>
			<= ISA_NEG_RESP SA Completed
			2.2.2 Identity Protection Exchange
			The identity protection exchange starts and ends the same as the base ex-
			change, but separates the key exchange payload and the authentication pay-
			loads into separate packets. In this exchange, the key exchange is trans-
			mitted first followed by the strong authentication exchange. The benefit
			of this exchange is the ability to communicate with a person without dis-
			closing either party's identity to passive attackers on the network.
			The ISA_KE_REQ and ISA_KE_RESP packets used for the key exchange portion of
			this exchange contain an ISAKMP header followed by the key exchange pay-
			load. The ISA_AUTH_REQ and ISA_AUTH_RESP packet used for the authentication
			portion of this exchange contain an ISAKMP header followed by the authen-
			tication payload.
			Identity Protection Exchange
			__Initiator___Direction___Responder___ Note
			ISA_INIT_REQ =>
			<= ISA_INIT_RESP
			Basic SA selected
			ISA_KE_REQ =>
			<= ISA_KE_RESP
			Key Generated
			Encryption Begun
			ISA_AUTH_REQ =>
			<= ISA_AUTH_RESP
			Identity Verified
			ISA_NEG_REQ =>
			<= ISA_NEG_RESP SA Completed
			2.2.3 Authentication Only Exchange
			The authentication only exchange starts and ends the same as the base ex-
			change. In this exchange, the authentication information is the only in-
			formation transmitted. The benefit of this exchange is the ability to
			perform only an authentication exchange without the computational expense
			of computing keys. Using this exchange, none of the transmitted informa-
			tion will be encrypted.
			The ISA_AUTH_REQ and ISA_AUTH_RESP packet used for the authentication only
			exchange contain an ISAKMP header followed by the authentication payload.
			Authentication Only Exchange
			__Initiator___Direction___Responder___ Note
			ISA_INIT_REQ =>
			<= ISA_INIT_RESP
			Basic SA selected
			ISA_AUTH_REQ =>
			<= ISA_AUTH_RESP
			Identity Verified
			ISA_NEG_REQ =>
			<= ISA_NEG_RESP SA Completed
			2.3 ISAKMP Details
			The following sections contain the details of ISAKMP. Sections 2.3.1
			through 2.3.7 cover details that are pertinent to the entire protocol.
			Sections 3 through 6 define the establishment, modification, and deletion
			services, defined as exchanges, offered by the protocol. The appendices
			provide examples of SAs and key exchanges.
			2.3.1 Basic ISAKMP Concepts
			Domain of Interpretation The Domain of Interpretation (DOI) identifier is
			used to interpret the payloads of ISAKMP payloads. The concept of a DOI
			is based on previous work by the IETF CIPSO Working Group, but extended
			beyond security label interpretation to include naming and interpretation
			of security services. The DOI defines:
			o The set of information that will be used to determine the required
			security services (this information is called a situation).
			o The set of security policies that must be supported.
			o Syntax rules for the specification of proposed security services. A
			set of security services is called a protection suite.
			o A common scheme for identifying cryptographic mechansisms, including
			encryption algorithms, key exchange algorithms, and certificate
			authorities.
			o A naming scheme for the cryptographic algorithms supported within the
			domain, and for common Key Exchange Identifiers.
			Specifications of the rules for individual DOIs will be presented in sep-
			arate documents. The rules for the Internet Security DOI is contained in
			Appendix A.
			A system may support multiple Domains of Interpretation. All systems MUST
			support the Internet Security DOI.
			Situation A situation contains all of the security-relevant information
			that a system considers necessary to decide the security services required
			to protect the session being negotiated. For example, in the Internet
			Security DOI (see Appendix A), the situation consists of only the address
			of the peer being contacted. In other DOIs, the situation may include
			security classifications, modes of operation (normal vs. emergency), etc.
			Protection Suite A protection suite is a list of the security services
			that must be applied at various security protocols. For example, a pro-
			tection suite may consist of DES encryption in IP ESP, and keyed MD5 in
			IP AH. All of the protections in a suite must be treated as a single unit.
			This is because security services in different security protocols can have
			subtle interactions, and the effects of a suite must be analyzed and veri-
			fied as a whole.
			Proposal A proposal is a list, in decreasing order of preference, of the
			protection suites that a system considers acceptable to protect traffic
			under a given situation.
			2.3.2 ISAKMP Header Format
			ISAKMP has a fixed header format (shown in Figure 2) followed by a vari-
	able length payload, optional digital signature, and optional padding. A		able length payload, optional digital signature, and optional padding. A
	fixed header simplifies parsing, providing the benefit of protocol parsing		fixed header simplifies parsing, providing the benefit of protocol parsing
	software that is less complex and easier to implement. The fixed header		software that is less complex and easier to implement. The fixed header
	contains the information required by the protocol to maintain state, pro-		contains the information required by the protocol to maintain state, pro-
	cess payloads and prevent attacks (e.g. denial of service and replay).		cess payloads and prevent attacks (e.g. denial of service and replay).
	Based on the message type, each header is followed by a payload specific		Based on the message type, each header is followed by a payload specific
	to the message type. The payload for each message is defined in sections		to the message type. The payload for each message is defined in sections
	3 through 6. Following the payload portion of the ISAKMP packet is a dig-		3 through 6. Following the payload portion of the ISAKMP packet is a dig-
	ital signature. This field is dependent on the negotiation of Security		ital signature. This field is dependent on the negotiation of Security
	Association attributes and may not be present.		Association attributes and may not be present.
	1 2 3		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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Message Type ! Exch ! Vers ! Length !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Security Parameter Index (SPI) !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! !		! !
	~ Initiator-Cookie ~		~ Initiator-Cookie ~
	! !		! !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! !		! !
	~ Responder-Cookie ~		~ Responder-Cookie ~
	! !		! !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! !		! Message Type ! Exch ! Vers ! Length !
	~ Payload ~
	! !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! !		! Security Parameter Index (SPI) !
	~ Digital Signature ~
	! !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! !		! Auxillary (SPI) !
	~ Padding ~
	! !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: ISAKMP Header Format		Figure 2: ISAKMP Header Format
	o Message Type (1 octet) - Indicates the type of message. A suffix of		o Message Type (1 octet) - Indicates the type of message. A suffix of
	REQ denotes a Request message type and an RESP suffix denotes a		REQ denotes a Request message type and an RESP suffix denotes a
	Response message type. The format and processing for each message is		Response message type. The format and processing for each message is
	defined in sections 3 through 6.		defined in sections 3 through 6.
	__ISAKMP_Message__Message_Type_		__ISAKMP_Message___Message_Type_
	RESERVED 0		RESERVED 0
	ISA_INIT_REQ 1		ISA_INIT_REQ 1
	ISA_INIT_RESP 2		ISA_INIT_RESP 2
	ISA_KE_REQ 3		ISA_KE_REQ 3
	ISA_KE_RESP 4		ISA_KE_RESP 4
	ISA_AUTH_REQ 5		ISA_AUTH_REQ 5
	ISA_AUTH_RESP 6		ISA_AUTH_RESP 6
	ISA_AUTH&KE_REQ 7		ISA_AUTH&KE_REQ 7
	ISA_AUTH&KE_RESP 8		ISA_AUTH&KE_RESP 8
	ISA_NEG_REQ 9		ISA_NEG_REQ 9
	ISA_NEG_RESP 10		ISA_NEG_RESP 10
	ISA_MODIFY_REQ 11		ISA_MODIFY_REQ 11
	ISA_MODIFY_RESP 12		ISA_MODIFY_RESP 12
	ISA_NOTIFY 13		ISA_NOTIFY 13
	ISA_DELETE 14		ISA_DELETE 14
	ISA_COMMIT 15		ISA_NEW_GROUP_REQ 15
	IANA Use 16-127		ISA_NEW_GROUP_RESP 16
	Future Use 128-255		IANA Use 17-127
			Future Use 128-255
	o Exchange (4 bits) - indicates the type of exchange, see section 2.2		o Exchange (4 bits) - indicates the type of exchange, see section 2.2
	for a description of the Message Types exchanged in each of these		for a description of the Message Types exchanged in each of these
	Exchange Types.		Exchange Types.
	___ISAKMP_Exchange___Exchange_Type__		___ISAKMP_Exchange___Exchange_Type__
	RESERVED 0		RESERVED 0
	Base 1		Base 1
	Identity Protection 2		Identity Protection 2
	Authentication Only 3		Authentication Only 3
	Future Use 4 - 15		Future Use 4 - 15
	o Version (4 bits) - indicates the version of the ISAKMP protocol in		o Version (4 bits) - indicates the version of the ISAKMP protocol in
	use.		use.
	o Length (2 octets) - Length of total message (header + payload) in		o Length (2 octets) - Length of total message (header + payload) in
	octets.		octets.
	o SPI (4 octets) - Security Parameter Index. The receiving entity's		o SPI (4 octets) - Security Parameter Index. The receiving entity's
	SPI is always in this field, except for the ISA_INIT packets. The		SPI is always in this field, except for the ISA_INIT packets. The use
	ISA_INIT packets contain the SPI the initiator expects to receive in		of the SPI field is described in Section 2.3.3
	all subsequent packets.
	o Initiator Cookie (16 octets) - Cookie of entity that initiated SA		o Auxillary SPI (4 octets) - The use of the Auxiliary SPI field is
			described in 2.3.3
			o Initiator Cookie (8 octets) - Cookie of entity that initiated SA
	establishment, SA modify or SA delete.		establishment, SA modify or SA delete.
	o Responder Cookie (16 octets) - Cookie of entity that is responding to		o Responder Cookie (8 octets) - Cookie of entity that is responding to
	an SA establishment, SA modify or SA delete request.		an SA establishment, SA modify or SA delete request.
	o Payload (variable) - The format of the payload is based on the		2.3.3 SPI Usage
	message type. These are defined in sections 3 through 6.
	o Signature - The digital signature of the initiator of the ISAKMP		While bootstrapping secure channels between systems, ISAKMP cannot assume
	message. This field will not be included on all packets and will be		the existence of security services, and must provide some protections for
	determined by the negotiated SA attributes.		itself. Therefore, ISAKMP distinguishes two different types of SPIs. The
			first type of SPI, called a negotiation SPI, refers to a ``local'' secu-
			rity association, implemented by the ISAKMP service itself. The second
			type is called a protection SPI, and is used to refer to the SA being de-
			veloped on behalf of other security protocols. Negotiation SPIs are mean-
			ingless outside of the negotiation server, while protection SPIs will be
			used by protocols such as AH and ESP.
	o Padding - This is an optional field that may be added depending on		Although SPIs are classified two different ways, all SPIs must be selected
	the type of encryption algorithm. If the encryption mechanism is		from the same SPI-space, so that the ISAKMP service can uniquely identify
	based on block encryption, then this field may be necessary to ensure		an SA based on a SPI.
	the packet is a specific size.
	2.1.1 General Message Processing		In general, the SPI field in the ISAKMP header contains the receiving en-
			tity's negotiation SPI. The only exception to this is the ISA_INIT_REQUEST
			message, because the receiver has not yet established a reciving SPI for
			the session. In the ISA_INIT_REQUEST message, the the SPI field contains
			the SPI that the sender will be using for the session.
			The Auxiliary SPI field is necessary because ISAKMP needs both a handle on
			the internal ``negotiation SA'', in order to protect or unprotect messages
			from ISAKMP peers, as well as a handle for the protection SA that is being
			developed.
			The following table describes the contents of the two SPI fields for each
			of the message types:
			__ISAKMP_Message_______SPI_____Auxiliary_SPI__
			ISA_INIT_REQ REQ NEG SPI 0
			ISA_INIT_RESP REQ NEG SPI REC NEG SPI
			ISA_KE_REQ REC NEG SPI REQ SPI
			ISA_KE_RESP REQ NEG SPI REC SPI
			ISA_AUTH_REQ REC NEG SPI REQ NEG SPI
			ISA_AUTH_RESP REQ NEG SPI REC NEG SPI
			ISA_AUTH&KE_REQ REC NEG SPI REQ NEG SPI
			ISA_AUTH&KE_RESP REQ NEG SPI REC NEG SPI
			ISA_NEG_REQ REC NEG SPI REQ PROT SPI
			ISA_NEG_RESP REC NEG SPI REC PROT SPI
			ISA_MODIFY_REQ REC NEG SPI REC SPI
			ISA_MODIFY_RESP REQ NEG SPI REQ SPI
			ISA_NOTIFY REC NEG SPI REC SPI
			ISA_DELETE REQ NEG SPI REQ SPI
			ISA_NEW_GROUP_REQ REC NEG SPI 0
			ISA_NEW_GROUP_RESPREQ NEG SPI 0
			Notes:
			REQ NEG SPI = Requestor's negotiation SPI
			REC NEG SPI = Receiver's negotiation SPI
			REQ PROT SPI = Requestor's protection SPI
			REC PROT SPI = Receiver's protection SPI
			REQ SPI = Requestor's SPI (either negotiation or protection)
			REC SPI = Receiver's SPI (either negotiation or protection)
			For KE messages: if the messages are establishing keys for a negotiation
			session, the SPI is a negotiation SPI. Otherwise, the Auxiliary SPI is a
			protection SPI.
			For MODIFY, NOTIFY, and DELETE messages: the Auxiliary SPI can refer to
			either type of SPI.
			2.3.4 General Message Processing
	Every ISAKMP message has basic processing applied to insure protocol re-		Every ISAKMP message has basic processing applied to insure protocol re-
	liability, and to minimize threats, such as denial of service and replay		liability, and to minimize threats, such as denial of service and replay
	attacks.		attacks.
	When transmitting an ISAKMP packet, the transmitting entity (initiator or		When transmitting an ISAKMP packet, the transmitting entity (initiator or
	responder) does the following:		responder) does the following:
	1. Sets a timer and initializes a retry counter.		1. Sets a timer and initializes a retry counter.
	skipping to change at page 17, line 5 ¶		skipping to change at page 23, line 22 ¶
	(b) No response is sent to the initiating entity. This will cause		(b) No response is sent to the initiating entity. This will cause
	the transmission timer of the initiating entity to expire and		the transmission timer of the initiating entity to expire and
	force retransmission of the message.		force retransmission of the message.
	5. The message payload is processed. Individual message processing is		5. The message payload is processed. Individual message processing is
	described in sections 3 through 6. Depending on the Message Type, a		described in sections 3 through 6. Depending on the Message Type, a
	valid message results in a response being sent to the transmitting		valid message results in a response being sent to the transmitting
	entity (message originator). The procedures for sending these		entity (message originator). The procedures for sending these
	responses are also outline in sections 3 through 6.		responses are also outline in sections 3 through 6.
	2.2 ISAKMP Packet Exchanges		2.3.5 Transport Protocol
	The Exchange field in the ISAKMP header currently has three values de-
	fined: the base exchange, the identity protection exchange, and the au-
	thentication only exchange. These exchanges define the flow of the ISAKMP
	packets during SA establishment. The diagrams in 2.2.1, 2.2.2, and 2.2.3
	show the packet exchange ordering for each exchange type and provide basic
	notes describing what has happened after each packet exchange.
	2.2.1 Base Exchange
	Sections 3.1 through 3.3 describe the three basic phases: SA Initial-
	ization, Key Exchange and Authentication, and SA Negotiation, that com-
	prise the base exchange. The base exchange contains the minimum number of
	packet exchanges in order to reduce latency associated with SA establish-
	ment.
	Base Exchange
	____Initiator____Direction_____Responder____ Note
	ISA_INIT_REQ =>
	<= ISA_INIT_RESP
	Basic SA selected
	ISA_AUTH&KE_REQ =>
	<= ISA_AUTH&KE_RESP
	Identity Verified
	Key Generated
	Encryption Begun
	ISA_NEG_REQ =>
	<= ISA_NEG_RESP SA Completed
	(optional) ISA_COMMIT =>
	2.2.2 Identity Protection Exchange
	The identity protection exchange starts and ends the same as the base ex-
	change, but separates the key exchange payload and the authentication pay-
	loads into separate packets. In this exchange, the key exchange is trans-
	mitted first followed by the strong authentication exchange. The benefit
	of this exchange is the ability to communicate with a person without dis-
	closing either party's identity to passive attackers on the network.
	The ISA_KE_REQ and ISA_KE_RESP packets used for the key exchange portion of
	this exchange contain an ISAKMP header followed by the key exchange pay-
	load. The ISA_AUTH_REQ and ISA_AUTH_RESP packet used for the authentication
	portion of this exchange contain an ISAKMP header followed by the authen-
	tication payload.
	Identity Protection Exchange
	__Initiator___Direction___Responder___ Note
	ISA_INIT_REQ =>
	<= ISA_INIT_RESP
	Basic SA selected
	ISA_KE_REQ =>
	<= ISA_KE_RESP
	Key Generated
	Encryption Begun
	ISA_AUTH_REQ =>
	<= ISA_AUTH_RESP
	Identity Verified
	ISA_NEG_REQ =>
	<= ISA_NEG_RESP SA Completed
	(optional) ISA_COMMIT =>
	2.2.3 Authentication Only Exchange
	The authentication only exchange starts and ends the same as the base ex-
	change. In this exchange, the authentication information is the only in-
	formation transmitted. The benefit of this exchange is the ability to
	perform only an authentication exchange without the computational expense
	of computing keys. Using this exchange, none of the transmitted informa-
	tion will be encrypted.
	The ISA_AUTH_REQ and ISA_AUTH_RESP packet used for the authentication only
	exchange contain an ISAKMP header followed by the authentication payload.
	Identity Protection Exchange
	__Initiator___Direction___Responder___ Note
	ISA_INIT_REQ =>
	<= ISA_INIT_RESP
	Basic SA selected
	ISA_AUTH_REQ =>
	<= ISA_AUTH_RESP
	Identity Verified
	ISA_NEG_REQ =>
	<= ISA_NEG_RESP SA Completed
	(optional) ISA_COMMIT =>
	2.3 ISAKMP Details
	2.3.1 Security Association Attributes
	A Security Association (SA) is a relationship between two entities that
	describes how they will utilize security services. This relationship is
	represented by a collection of security related information. The SA At-
	tributes are the individual elements that comprise all security relevant
	information necessary to form the SA.
	The following syntax defines the security attributes to be exchanged by
	ISAKMP. This syntax is used in the ISA_INIT_REQ, ISA_INIT_RESP, ISA_NEG_REQ,
	ISA_NEG_RESP, ISA_MOD_REQ, and ISA_MOD_RESP messages. The syntax groups se-
	curity attributes needed to perform a security function into either an SA
	set or SA list format. The set format MUST be supported by ISAKMP imple-
	mentations. The list format is an optional format.
	Security Associations Sets The set format groups all necessary attributes
	together. Each set has a unique identifier (Set Number), supported secu-
	rity service (Supports), such as IP AH, IP ESP, OSPF authentication, and
	a list of Attribute Classes and Attribute Types. The Attribute Class is
	the broad category of Attribute Type, such as encryption algorithms. At-
	tribute Type is a specific attribute identifier. DES is an example of an
	attribute type for the encryption algorithm attribute class. A set has
	only one instance of an Attribute Class and one type for that class. This
	syntax maintains flexibility by allowing many different (and some still
	undefined) types of SA attributes to be exchanged.
	Figure 2 depicts the syntax for exchanging security attributes using
	the set format. It shows a single set from which multiple sets would be
	grouped for a specific message type.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Set Number ! Supports ! Num of Attr !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Attribute Class ! Attribute Type !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ..... ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Attribute Class ! Attribute Type !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 2: Generic Set Exchange Format
	o Set number (1 octet) - Unique identifier for each proposed set
	o Supports (2 octets) - Security service proposed set supports.
	Examples are IP AH, IP ESP, and OSPF authentication
	o Number of Attributes (1 octet) - Number of attribute classes
	contained in the proposed set
	o Attribute Class (2 octets) - examples are Encryption Algorithms, Key
	Exchange Algorithms, Authentication Mechanisms
	o Attribute Type (2 octets) - examples of attribute types for the
	encryption algorithms attribute class are DES, Triple DES, and IDEA.
	The size of a set formatted exchange is 4 octets + (Number of Attribute
	Classes * 4 octets). Computing the size of a particular set allows the
	determination of the beginning of the next set without completely parsing
	the current set. This is necessary when it is determined that the current
	set is not an acceptable SA set. This will improve the performance of SA
	Attribute determination.
	Security Association Lists The SA list format presents several attribute
	types for an attribute class. Each type within the class is then ordered
	to indicate its precedence. Specifically, the first attribute type is the
	highest priority type, followed by other choices. Each subsequent choice
	is listed in descending priority order. An attribute type must be chosen
	for each attribute class to establish a complete SA.
	Figure 3 shows the syntax for the optional list exchange format. The num-
	ber of types is determined by the Count field. The number of Attribute
	Types within an Attribute Class will depend on what is supported by the
	local machine.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Attribute Class ! Count !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Attribute Type ! Attribute Type !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Attribute Type ! Attribute Type !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 3: Generic List Exchange Format
	o Attribute Class (2 octets) - Examples are Encryption Algorithms, Key
	Exchange Algorithms
	o Count - Number of proposed Attribute Types for the given Attribute
	Class
	o Attribute Type (2 octets) - Presented in descending priority order
	Appendix B presents an outline containing a comprehensive listing of SA
	attributes. This listing of attributes are initial definitions and are
	presented to stimulate thought and discussion on SAs. The final SA for
	a protocol SHOULD be defined in that protocol so additions or modifica-
	tions to the attributes do not require a modification to the Internet Key
	Management Protocol (IKMP) RFC and vice versa. For example, Appendix C
	describes the sample security associations for ISAKMP and IPSP ESP and AH.
	2.3.2 Transport Protocol
	The User Datagram Protocol (UDP) is the transport protocol for ISAKMP. UDP		ISAKMP can be implemented over any transport protocol or IP itself. The
	checksumming discards UDP packets with an incorrect or zero (0) checksum.		User Datagram Protocol (UDP) is minimum requirement for interoperability.
	ISAKMP is unaware of the discard, but will resend the packet when its re-		The ISAKMP well-known port is TBD.
	send timer expires.
	2.3.3 RESERVED Fields		2.3.6 RESERVED Fields
	The existence of RESERVED fields are strictly used to preserve byte		The existence of RESERVED fields are strictly used to preserve byte align-
	alignement. All RESERVED fields in the ISAKMP protocol MUST be set to		ment. All RESERVED fields in the ISAKMP protocol MUST be set to zero (0)
	zero (0) when a packet is issued. The receiver SHOULD check the RESERVED		when a packet is issued. The receiver SHOULD check the RESERVED fields
	fields for zero (0) and discard the packet if other values are found.		for zero (0) and discard the packet if other values are found.
	2.3.4 Anti-Clogging Token (``Cookie'') Creation		2.3.7 Anti-Clogging Token (``Cookie'') Creation
	Phil Karn's Internet Draft [Karn95] states that cookie generation is im-		Phil Karn's Internet Draft [Karn] states that cookie generation is imple-
	plementation dependent, but must satisfy some basic requirements:		mentation dependent, but must satisfy some basic requirements:
	1. The cookie must depend on the specific parties. This prevents		1. The cookie must depend on the specific parties. This prevents
	an attacker from obtaining a cookie using a real IP address and		an attacker from obtaining a cookie using a real IP address and
	UDP port, and then using it to swamp the victim with Diffie-		UDP port, and then using it to swamp the victim with Diffie-
	Hellman requests from randomly chosen IP addresses or ports.		Hellman requests from randomly chosen IP addresses or ports.
	2. It must not be possible for anyone other than the issuing		2. It must not be possible for anyone other than the issuing
	entity to generate cookies that will be accepted by that		entity to generate cookies that will be accepted by that
	entity. This implies that the issuing entity must use local		entity. This implies that the issuing entity must use local
	secret information in the generation and subsequent		secret information in the generation and subsequent
	skipping to change at page 22, line 19 ¶		skipping to change at page 25, line 5 ¶
	3. The cookie generation function must be fast to thwart attacks		3. The cookie generation function must be fast to thwart attacks
	intended to sabotage CPU resources.		intended to sabotage CPU resources.
	Karn's suggested method for creating the cookie is to perform a fast hash		Karn's suggested method for creating the cookie is to perform a fast hash
	(e.g. MD5) over the IP Source and Destination Address, the UDP Source and		(e.g. MD5) over the IP Source and Destination Address, the UDP Source and
	Destination Ports and a locally generated secret random value. ISAKMP		Destination Ports and a locally generated secret random value. ISAKMP
	requires that the cookie be unique for each SA establishment, SA modify		requires that the cookie be unique for each SA establishment, SA modify
	and SA delete to help prevent replay attacks, therefore the date and time		and SA delete to help prevent replay attacks, therefore the date and time
	MUST be added to the information hashed.		MUST be added to the information hashed.
	2.3.5 SA Flags Field
	The SA Flags field may be set by the entity that initiated the negotia-
	tion to indicate that the ISA_COMMIT packet will follow the completion of
	the protocol exchange. The SA Flags field exists only in the ISA_INIT and
	ISA_NEG packets. If the initiating entity sets the flag, the responding
	entity cannot reset it. If the initiating entity does not set the flag,
	the responding entity may set it, thereby, forcing the initiating entity
	to issue an ISA_COMMIT packet. If neither entity sets the flag, then the
	ISA_COMMIT packet will not be issued. To set the flag the Least Signifi-
	cant Bit (LSB) in the SA Flags field is set to one (1) . All other bits
	in the SA Flags field are zero (0).
	3 Security Association Establishment		3 Security Association Establishment
	Security Association (SA) Establishment is the process of agreeing upon		Security Association (SA) Establishment is the process of agreeing upon
	and exchanging all the security information that is required in an SA. The		and exchanging all the security information that is required in an SA. The
	following sections, 3.1 to 3.3, describe the three basic phases that com-		following sections, 3.1 to 3.3, describe the three basic phases that com-
	prise SA Establishment: SA Initialization, Key and Authentication infor-		prise SA Establishment: SA Initialization, Key and Authentication infor-
	mation exchange, and SA Negotiation.		mation exchange, and SA Negotiation.
	3.1 Security Association Initialization		3.1 Security Association Initialization
	The initialization exchange of SA establishment is composed of the		The initialization exchange of SA establishment is composed of the
	ISA_INIT_REQ and ISA_INIT_RESP packets shown in figure 4. The ISA_INIT pack-		ISA_INIT_REQ and ISA_INIT_RESP packets shown in figure 3. The ISA_INIT pack-
	ets exchange ``cookies'', and options for a key generation technique, an		ets exchange ``cookies'', and options for a key generation technique, an
	encryption algorithm and an authentication mechanism. The ``cookies''		encryption algorithm and an authentication mechanism. The ``cookies''
	are used to prevent replay and denial of service attacks. Authentication		are used to prevent replay and denial of service attacks. Authentication
	and encryption for the ISAKMP exchanges are provided by the authentication		and encryption for the ISAKMP exchanges are provided by the authentication
	mechanism and encryption algorithm selected. The key generation technique		mechanism and encryption algorithm selected. The key generation technique
	selected creates keys for use by the authentication mechanism and encryp-		selected creates keys for use by the authentication mechanism and encryp-
	tion algorithm. The keys may also be used as any of the following: ac-		tion algorithm. The keys may also be used as any of the following: ac-
	tual session keys, to create the session keys, or to protect the exchange		tual session keys, to create the session keys, or to protect the exchange
	of the actual session keys for the SA. If the key, encryption algorithm,		of the actual session keys for the SA. If the key, encryption algorithm,
	and authentication mechanism are only used to protect ISAKMP exchanges,		and authentication mechanism are only used to protect ISAKMP exchanges,
	then new options can be picked during the negotiation phase (described in		then new options can be picked during the negotiation phase (described in
	Section 3.3) for use in protecting the actual data communications. If en-		Section 3.3) for use in protecting the actual data communications. If en-
	cryption is not required for the SA, the encryption algorithm options are		cryption is not required for the SA, the encryption algorithm options are
	not exchanged.		not exchanged.
	1 2 3		o ISAKMP Header - Described in Section 2.3.2
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ISAKMP Header ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! SA Syntax Type! SA Flags ! # Sets/Lists ! RESERVED !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ SA Attribute Set/List #1 ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ SA Attribute Set/List #2 ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ... ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ SA Attribute Set/List #N ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 4: ISA_INIT_REQ and ISA_INIT_RESP Packet Format
	o ISAKMP Header - Described in Section 2.1		o Next Payload (1 octet) - Identifies the next payload in an ISAKMP
			message if more then one is carried in a message.
	o SA Syntax Type (1 octet) - Presentation format of SAs		o Payload Length (1 octet) - Specifies the payload length in 4-octet
			units.
	_SA_Syntax__SA_Syntax_Type_		o Situation - Variable length field containing the situation for an SA
	RESERVED 0		(described in section 2.3.1).
	Set 1
	List 2
	o SA Flags (1 octet) - Flags specific to an SA service. See section		o Proposal - Variable length field containing a list of proposed
	2.3.5 for details.		protection suites for an SA (described in section 2.3.1).
	o Number of Sets (1 octet) - Number of SA Attribute Sets being proposed		The format and content of both the situation and proposal is DOI-specific.
	o SA Attributes (variable) - A list of SA Attributes. The SA Attribute		The format of the Internet Security situation and proposal is described in
	specifications are discussed in Section 2.3.1.		Appendix A.
	3.1.1 SA Initialization Procedures		3.1.1 SA Initialization Procedures
	When issuing an ISA_INIT_REQ message, the initiating entity does the fol-		When issuing an ISA_INIT_REQ message, the initiating entity does the fol-
	lowing:		lowing:
	1. Create initiator cookie. See Section 2.3.4 for details.		1. Create initiator cookie. See Section 2.3.7 for details.
	2. Generate a unique pseudo-random SPI. See Section 2.1 for details.		2. Generate a unique pseudo-random negotiation SPI. See Section 2.3.2
			for details.
	3. Construct an ISA_INIT_REQ packet. If the initiator will send an		3. Determine the relevant security characteristics of the session (the
	ISA_COMMIT message upon completion of the SA establishment, then the		situation).
	SA Flags field MUST be set (see section 2.3.5 and 3.4).
	4. Transmit the packet to the destination host as described in Section		4. Generate a proposal for protecting a session under that situation.
	2.1.1.
			5. Construct an ISA_INIT_REQ packet.
			6. Transmit the packet to the destination host as described in Section
			2.3.4.
	When an ISA_INIT_REQ message is received, the receiving entity does the		When an ISA_INIT_REQ message is received, the receiving entity does the
	following:		following:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Unpack the ISA_INIT_REQ payload and determine the highest priority		2. Unpack the ISA_INIT_REQ payload.
	attribute set (or attribute list) supported. If the proposed
	attribute set (or list) is rejected, then the protocol machine must
	clear all state and return to IDLE.
	3. Create responder cookie. See Section 2.3.4 for details.		3. Determine if the given situation can be protected. If not, the pro-
			tocol machine must send a rejection notification and return to IDLE.
	4. Generate a unique pseudo-random SPI. See Section 2.1 for details.		4. Determine if it can use any of the proposed protection suites to
			protect the session. If none of the proposed suites are acceptable,
			then the protocol machine must send a rejection notification, clear
			all state and return to IDLE.
	5. Construct an ISA_INIT_RESP packet. If the responder wants to request		5. Create responder cookie. See Section 2.3.7 for details.
	that an ISA_COMMIT message be sent upon completion of the SA
	establishment, then the SA Flags field MUST be set (see section 2.3.5
	and 3.4).
	6. Transmit the packet to the initiating host as described in Section		6. Generate a unique pseudo-random SPI. See Section 2.3.2 for details.
	2.1.1.
			7. Construct an ISA_INIT_RESP packet containing the situation and the
			chosen protection suite.
			8. Transmit the packet to the initiating host as described in Section
			2.3.4.
	When an ISA_INIT_RESP message is received, the receiving entity (original		When an ISA_INIT_RESP message is received, the receiving entity (original
	initiator) does the following:		initiator) does the following:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Unpack the ISA_INIT_RESP payload.		2. Unpack the ISA_INIT_RESP payload.
	3. Determine if the attribute set (or list) selected by the responder is		3. Determine that the situation returned is the same as the one sent.
	valid. If the attribute set (or list) is invalid or the responder		If not, the protocol machine must send a rejection notification and
	rejected all proposed attribute sets (or lists), the receiving entity		possibly resend the ISA_INIT_REQ message.
	does the following:
			4. Determine if the returned protection suite is among the set of valid
			choices. If the entire proposal was rejected, the event
			PROPOSAL_REJECTED is logged to the appropriate audit file. If an
			invalid protection suite was returned, the receiving entity does the
			following:
	(a) The event, INVALID ATTRIBUTES, is logged in the appropriate		(a) The event, INVALID ATTRIBUTES, is logged in the appropriate
	system audit file.		system audit file.
	(b) Clear all state and return to IDLE. Any further communication		(b) Clear all state and return to IDLE. Any further communication
	must start the SA initialization procedures from the beginning.		must start the SA initialization procedures from the beginning.
	If the attribute set (or list) is valid, the receiving entity does		If a valid protection suite was selected, the receiving entity does
	the following:		the following:
	(a) Configure protocol machine based on attribute set selected.		(a) Configure protocol machine based on protection suite selected.
	(b) Transition to Authentication and Key Exchange (see Section 3.2).		(b) Transition to Authentication and Key Exchange (see Section 3.2).
	3.2 Authentication and Key Exchange		3.2 Authentication and Key Exchange
	During the authentication and key exchange phase, information required to		During the authentication and key exchange phase, information required to
	confirm the identities of the parties wishing to establish the SA and es-		confirm the identities of the parties wishing to establish the SA and es-
	tablish a session key for use during the SA establishment is exchanged.		tablish session keys for use during the SA establishment is exchanged.
	Depending on the key exchange algorithm, the original key may be used dur-		Depending on the key exchange algorithms, the original key may be used
	ing data communications or a new one may be created and exchanged during		during data communications or a new one may be created and exchanged dur-
	the negotiation phase (described in section 3.3). This original or new		ing the negotiation phase (described in section 3.3). This original or
	key would be used in protecting the actual data communications.		new key would be used in protecting the actual data communications.
	The packets that carry the authentication and key exchange payloads have		The packets that carry the authentication and key exchange payloads have
	the format shown in Figure 5. When the ISA_AUTH&KE_REQ and ISA_AUTH&KE_RESP		the format shown in Figure 4. When the ISA_AUTH&KE_REQ and ISA_AUTH&KE_RESP
	packets are used, the Authentication Payload SHOULD be processed first to		packets are used, the Authentication Payload SHOULD be processed first to
	strongly authenticate the packet issuer, followed by the processing of		strongly authenticate the packet issuer, followed by the processing of the
	the Key Exchange Payload. The authentication and key exchange payloads		Key Exchange Payload. The authentication and key exchange payloads (shown
	(shown in Figures 6 and 7) are general formats which support many types		in Figures 5 and 6) are general formats which support many types of au-
	of authentication and key exchange mechanisms. The detailed specification		thentication and key exchange mechanisms. The detailed specification of
	of these fields will be specified in companion RFCs. These companion RFCs		these fields will be specified in companion RFCs. These companion RFCs
	will define the standard authentication and key exchange mechanisms that		will define the standard authentication and key exchange mechanisms that
	need to be implemented to assure compliance with this specification.		need to be implemented to assure compliance with this specification. The
			format for the Internet Security DOI key exchange and authentication pay-
	1 2 3		loads is described in A
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ISAKMP Header ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~
	! Authentication Payload !
	~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~
	! Key Exchange Payload !
	~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 5: ISA_AUTH&KE_REQ and ISA_AUTH&KE_RESP Packet Format
	3.2.1 Authentication Payload Format		3.2.1 Authentication Payload Format
	This section specifies the encoding of the authentication payload for the		This section specifies the encoding of the authentication payload for the
	ISA_AUTH_REQ, ISA_AUTH_RESP, ISA_AUTH&KE_REQ, and ISA_AUTH&KE_RESP messages.		ISA_AUTH_REQ, ISA_AUTH_RESP, ISA_AUTH&KE_REQ, and ISA_AUTH&KE_RESP messages.
	As described in section 2.2.3, when the ISA_AUTH_REQ and ISA_AUTH_RESP pack-		As described in section 2.2.3, when the ISA_AUTH_REQ and ISA_AUTH_RESP pack-
	ets are transmitted alone, the key exchange payload is not present. The		ets are transmitted alone, the key exchange payload is not present. The
	format of these messages is shown in Figure 6.		format of these messages is shown in Figure 5.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Authentication Authority ! Reserved !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Authentication Type ! Length !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~
	! Authentication Data !
	~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 6: Authentication Payload Format
	o Authentication Authority (2 octets) - This field identifies the party		o Authentication Authority (2 octets) - This field identifies the party
	that generated the certificates used for authentication. Authorities		that generated the certificates used for authentication. Authorities
	must be assigned an identifier by the Internet Assigned Numbers		must be assigned an identifier by the Internet Assigned Numbers
	Authority (IANA). Before being assigned an identifier, an authority		Authority (IANA). Before being assigned an identifier, an authority
	must publish an RFC defining the authority's domain. [RFC-1422]		must publish an RFC defining the authority's domain. [RFC-1422]
	describes the Internet Policy Registration Authority (IPRA) and the		describes the Internet Policy Registration Authority (IPRA) and the
	procedures for achieving this registration.		procedures for achieving this registration.
	If PGP certificates, based on the ``web of trust'', are carried in		If PGP certificates, based on the ``web of trust'', are carried in
	skipping to change at page 27, line 34 ¶		skipping to change at page 29, line 22 ¶
	-- U.S. Postal Service.		-- U.S. Postal Service.
	o Authentication Type (2 octets) - This field indicates the		o Authentication Type (2 octets) - This field indicates the
	authentication payload format. This field is used by authentication		authentication payload format. This field is used by authentication
	authorities that support more than one certificate type. The		authorities that support more than one certificate type. The
	authentication types supported by an authentication authority must be		authentication types supported by an authentication authority must be
	defined in the RFC required for authentication authority		defined in the RFC required for authentication authority
	registration. Examples are:		registration. Examples are:
	-- RSA certificates		-- PKCS #7 certificates
	-- PGP certificates		-- PGP certificates
	-- DSS certificates
	-- DNS Signed Keys		-- DNS Signed Keys
	-- Kerberos Tokens		-- Kerberos Tokens
	-- X.509 certificates		-- X.509 certificates
	o Length (2 octets) - Length of the Authentication Data field in		o Length (2 octets) - Length of the Authentication Data field in
	octets.		octets.
	o Authentication Data (variable) - Actual authentication data. The		o Authentication Data (variable) - Actual authentication data. The
	type of certificate is indicated by the Authentication Type field.		type of certificate is indicated by the Authentication Type field.
	3.2.2 Key Exchange Payload Format		3.2.2 Key Exchange Payload Format
	A variety of key exchanges can be supported in the key exchange phase.		A variety of key exchanges can be supported in the key exchange phase.
	Some examples of key exchanges which may be used in this protocol are		Some examples of key exchanges which may be used in this protocol are Oak-
	Diffie-Hellman, the enhanced Diffie-Hellman key exchange described in		ley [Oakley], Diffie-Hellman, the enhanced Diffie-Hellman key exchange de-
	X9.42 [ANSI94], the key exchange on the FORTEZZA card, and the RSA-based		scribed in X9.42 [ANSI], the Key Exchange Algorithm (KEA) on the FORTEZZA
	key exchange used by PGP. This protocol will also support key exchanges		card, and the RSA-based key exchange used by PGP. This protocol will also
	that include key escrow or data recovery techniques, but does not mandate		support key exchanges that include key escrow or data recovery techniques,
	their use.		but does not mandate their use.
	The encoding of the key exchange payload is dependent on the specific key
	exchange and, therefore, is not specified in this Internet draft. Each
	key exchange must define the following information: (a) System parame-
	ters, (b) Key establishment algorithm, and (c) Key derivation procedure
	(dependent on key exchange type).
	There can be both public and private key generation techniques. Both		ISAKMP supports both public and private key generation techniques. Both
	types must register with IANA to obtain a Key Exchange Identifier (KEI).		types must register with IANA to obtain a Key Exchange Identifier (KEI).
	Before published public key exchanges can obtain a KEI, an RFC defining		Before published public key exchanges can obtain a KEI, an RFC defining
	the key exchange payload format and key generation procedures MUST be sub-		the key exchange payload format and key generation procedures MUST be sub-
	mitted. Private key exchanges SHOULD be documented in an RFC when regis-		mitted. Private key exchanges SHOULD be documented in an RFC when regis-
	tering for a KEI.		tering for a KEI.
			The encoding of the key exchange payload is dependent on the specific key
			exchange and, therefore, is not specified in this Internet draft. Each
			key exchange must define the following information: (a) System parame-
			ters, (b) Key establishment algorithm, and (c) Key derivation procedure
			(dependent on key exchange type). See [Oakley] for an example of a key
			exchange that can be executed during the ISAKMP key exchange phase.
	As described in section 2.2.2, when the ISA_KE_REQ and ISA_KE_RESP packets		As described in section 2.2.2, when the ISA_KE_REQ and ISA_KE_RESP packets
	are transmitted alone, the authentication payload is not present. Once		are transmitted alone, the authentication payload is not present. Once
	the key exchange is completed, then the authentication payload is sent		the key exchange is completed, then the authentication payload is sent
	separately using the format described in section 3.2.1		separately using the format described in section 3.2.1
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! KEI ! Length !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~
	! Key Exchange Payload !
	~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 7: Key Exchange Payload Format
	o KEI (2 octets) - Key Exchange Identifier
	o Length (2 octets) - Length of payload in octets
	o Key Exchange Payload (variable) - Data (i.e. public values) required
	to create session key.
	3.2.3 Authentication and Key Exchange Procedures		3.2.3 Authentication and Key Exchange Procedures
	When issuing an ISA_AUTH&KE_REQ packet, the initiating entity will do the		When issuing an ISA_AUTH&KE_REQ packet, the initiating entity will do the
	following:		following:
	1. Create the ISAKMP Header.		1. Create the ISAKMP Header.
	2. Create the authentication payload.		2. Create the authentication payload.
	3. Create the key exchange payload based on KEI.		3. Create the key exchange payload based on KEI.
	4. Construct an ISA_AUTH&KE_REQ packet.		4. Construct an ISA_AUTH&KE_REQ packet.
	5. Generate an authentication signature using the authentication		5. Generate an authentication signature using the authentication
	attributes and options selected in the initialization phase.		attributes and options selected in the initialization phase.
	6. Transmit the packet to the responding host as described in Section		6. Transmit the packet to the responding host as described in Section
	2.1.1.		2.3.4.
	When an ISA_AUTH&KE_REQ packet is received, the receiving entity will do		When an ISA_AUTH&KE_REQ packet is received, the receiving entity will do
	the following:		the following:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Verify the initiator's signature. The ISA_AUTH&KE_REQ packet is		2. Verify the initiator's signature. The ISA_AUTH&KE_REQ packet is
	processed and the calculated signature is compared to the signature		processed and the calculated signature is compared to the signature
	contained in the ISA_AUTH&KE_REQ packet. If these signatures are not		contained in the ISA_AUTH&KE_REQ packet. If these signatures are not
	identical, the message is discarded and the following actions are		identical, the message is discarded and the following actions are
	taken:		taken:
	(a) The event, INVALID SIGNATURE, is logged in the appropriate system		(a) The event, INVALID SIGNATURE, is logged in the appropriate system
	audit file.		audit file.
	skipping to change at page 30, line 11 ¶		skipping to change at page 31, line 26 ¶
	5. Create the authentication payload.		5. Create the authentication payload.
	6. Create the key exchange payload based on KEI.		6. Create the key exchange payload based on KEI.
	7. Construct an ISA_AUTH&KE_RESP packet.		7. Construct an ISA_AUTH&KE_RESP packet.
	8. Generate an authentication signature, to authenticate responder to		8. Generate an authentication signature, to authenticate responder to
	initiator, using the authentication attributes and options selected.		initiator, using the authentication attributes and options selected.
	9. Transmit the packet to the initiating host as described in Section		9. Transmit the packet to the initiating host as described in Section
	2.1.1.		2.3.4.
	10. Begin key calculation in the background, if necessary.		10. Begin key calculation in the background, if necessary.
	When an ISA_AUTH&KE_RESP message is received, the receiving entity (origi-		When an ISA_AUTH&KE_RESP message is received, the receiving entity (origi-
	nal initiator) will do the following:		nal initiator) will do the following:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Verify the initiator's signature. The ISA_AUTH&KE_RESP packet is		2. Verify the initiator's signature. The ISA_AUTH&KE_RESP packet is
	processed and the calculated signature is compared to the signature		processed and the calculated signature is compared to the signature
	contained in the ISA_AUTH&KE_RESP packet. If these signatures are not		contained in the ISA_AUTH&KE_RESP packet. If these signatures are not
	identical, the message is discarded and the following actions are		identical, the message is discarded and the following actions are
	taken:		taken:
	(a) The event, INVALID SIGNATURE, is logged in the appropriate system		(a) The event, INVALID SIGNATURE, is logged in the appropriate system
	audit file.		audit file.
	skipping to change at page 30, line 47 ¶		skipping to change at page 32, line 15 ¶
	3.3 Security Association Negotiation		3.3 Security Association Negotiation
	The SA Negotiation phase allows the initiating entity to present SA at-		The SA Negotiation phase allows the initiating entity to present SA at-
	tributes that it wishes to use for secure communications to a respond-		tributes that it wishes to use for secure communications to a respond-
	ing entity. These SA attributes may include additional options for the		ing entity. These SA attributes may include additional options for the
	attributes agreed upon during the initialization phase, as well as ad-		attributes agreed upon during the initialization phase, as well as ad-
	ditional attributes required for an SA. As an example, the SA parame-		ditional attributes required for an SA. As an example, the SA parame-
	ters for the IP AH and IP ESP security mechanisms are cited in the Secu-		ters for the IP AH and IP ESP security mechanisms are cited in the Secu-
	rity Architecture for the Internet Protocol [RFC-1825]. The format for		rity Architecture for the Internet Protocol [RFC-1825]. The format for
	the ISA_NEG_REQ and ISA_NEG_RESP packets is the same as the ISA_INIT_REQ and		the ISA_NEG_REQ and ISA_NEG_RESP packets is the same as the ISA_INIT_REQ and
	ISA_INIT_RESP shown in Figure 4. All fields shown in Figure 4 exist for		ISA_INIT_RESP shown in Figure 3. All fields shown in Figure 3 exist for
	the ISA_NEG_REQ and ISA_NEG_RESP packets.		the ISA_NEG_REQ and ISA_NEG_RESP packets.
	3.3.1 SA Negotiation Procedures		3.3.1 SA Negotiation Procedures
	When issuing an ISA_NEG_REQ packet, the initiating entity does the follow-		When issuing an ISA_NEG_REQ packet, the initiating entity does the follow-
	ing:		ing:
	1. Determine SA attributes to be negotiated. This may include changing		1. Determine SA attributes to be negotiated. This may include changing
	some attributes from the original SA initialization.		some attributes from the original SA initialization.
	2. Construct an ISA_NEG_REQ packet. If the initiator will send an		2. Construct an ISA_NEG_REQ packet.
	ISA_COMMIT message upon completion of the SA establishment, then the
	SA Flags field MUST be set (see section 2.3.5 and 3.4).
	3. Depending on the SA Attributes established in the SA initialization		3. Depending on the SA Attributes established in the SA initialization
	phase, apply the agreed upon security services.		phase, apply the agreed upon security services.
	(a) If the SA requires authentication, the ISA_NEG_REQ packet is pro-		(a) If the SA requires authentication, the ISA_NEG_REQ packet is pro-
	cessed (or signed) and the signature placed as noted in Figure 1.		cessed (or signed) and the signature placed as noted in Figure 2.
	(b) If the SA requires encryption and the encryption algorithm is a		(b) If the SA requires encryption and the encryption algorithm is a
	block encryption algorithm, then padding up to the block size		block encryption algorithm, then padding up to the block size
	MUST be placed as noted in Figure 1.		MUST be placed as noted in Figure 2.
	(c) If the SA requires encryption, the ISA_NEG_REQ payload and		(c) If the SA requires encryption, the ISA_NEG_REQ payload and
	Signature are encrypted.		Signature are encrypted.
	4. Transmit the packet to the responding host as described in Section		4. Transmit the packet to the responding host as described in Section
	2.1.1.		2.3.4.
	When an ISA_NEG_REQ packet is received, the receiving entity does the fol-		When an ISA_NEG_REQ packet is received, the receiving entity does the fol-
	lowing:		lowing:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Depending on the SA Attributes, apply the agreed upon security		2. Depending on the SA Attributes, apply the agreed upon security
	services.		services.
	(a) If the SA requires encryption, decrypt the ISA_NEG_REQ payload and		(a) If the SA requires encryption, decrypt the ISA_NEG_REQ payload and
	Signature. If the decryption fails, the message is discarded and		Signature. If the decryption fails, the message is discarded and
	the following actions are taken:		the following actions are taken:
	i. The event, DECRYPTION FAILED, is logged in the appropriate		i. The event, DECRYPTION FAILED, is logged in the appropriate
	system audit file.		system audit file.
	skipping to change at page 32, line 31 ¶		skipping to change at page 33, line 41 ¶
	3. Unpack the ISA_NEG_REQ packet payload and determine the highest		3. Unpack the ISA_NEG_REQ packet payload and determine the highest
	priority SA attributes supported. If none of the SA attribute		priority SA attributes supported. If none of the SA attribute
	options are supported, the ISA_NEG_RESP packet will have the value zero		options are supported, the ISA_NEG_RESP packet will have the value zero
	(0) in the Number of Sets field and an SA will not be established.		(0) in the Number of Sets field and an SA will not be established.
	4. If the SA negotiation is requesting a key change or new		4. If the SA negotiation is requesting a key change or new
	authentication mechanism, then generate the appropriate information		authentication mechanism, then generate the appropriate information
	and include it as an attribute in the ISA_NEG_RESP payload.		and include it as an attribute in the ISA_NEG_RESP payload.
	5. Construct an ISA_NEG_RESP packet. If the responder wants to request		5. Construct an ISA_NEG_RESP packet.
	that an ISA_COMMIT message be sent upon completion of the SA
	establishment, then the SA Flags field MUST be set (see section 2.3.5
	and 3.4).
	6. Depending on the SA Attributes, apply the agreed upon security		6. Depending on the SA Attributes, apply the agreed upon security
	services.		services.
	(a) If the SA requires authentication, the ISA_NEG_RESP packet is		(a) If the SA requires authentication, the ISA_NEG_RESP packet is
	processed and the signature placed as noted in Figure 1.		processed and the signature placed as noted in Figure 2.
	(b) If the SA requires encryption and the encryption algorithm is a		(b) If the SA requires encryption and the encryption algorithm is a
	block encryption algorithm, then padding up to the block size		block encryption algorithm, then padding up to the block size
	MUST be placed as noted in Figure 1.		MUST be placed as noted in Figure 2.
	(c) If the SA requires encryption, the ISA_NEG_RESP payload and		(c) If the SA requires encryption, the ISA_NEG_RESP payload and
	Signature are encrypted.		Signature are encrypted.
	7. Transmit the packet to the initiating host as described in Section		7. Transmit the packet to the initiating host as described in Section
	2.1.1.		2.3.4.
	8. If required, begin calculation of the new session key in the		8. If required, begin calculation of the new session key in the
	background.		background.
	9. Transition to SA Negotation Conclusion (see Section 3.4).		9. Return appropriate data (i.e. SA, SPI) to negotiation server, clear
			all state, and return to IDLE.
	When an ISA_NEG_RESP message is received, the receiving entity (original		When an ISA_NEG_RESP message is received, the receiving entity (original
	initiator) does the following:		initiator) does the following:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Depending on the SA Attributes, apply the agreed upon security		2. Depending on the SA Attributes, apply the agreed upon security
	services.		services.
	(a) If the SA requires encryption, decrypt the ISA_NEG_RESP payload and		(a) If the SA requires encryption, decrypt the ISA_NEG_RESP payload and
	Signature. If the decryption fails, the message is discarded and		Signature. If the decryption fails, the message is discarded and
	the following actions are taken:		the following actions are taken:
	i. The event, DECRYPTION FAILED, is logged in the appropriate		i. The event, DECRYPTION FAILED, is logged in the appropriate
	system audit file.		system audit file.
	skipping to change at page 34, line 19 ¶		skipping to change at page 35, line 28 ¶
	If the attribute set (or list) is valid, the receiving entity does		If the attribute set (or list) is valid, the receiving entity does
	the following:		the following:
	(a) Configure the protocol machine based on the attribute set (or		(a) Configure the protocol machine based on the attribute set (or
	list) selected.		list) selected.
	4. If required, begin calculation of the new session key in the		4. If required, begin calculation of the new session key in the
	background.		background.
	5. Transition to SA Negotiation Conclusion (see Section 3.4).		5. Return appropriate data (i.e. SA, SPI) to negotiation server, clear
			all state, and return to IDLE.
	3.4 SA Negotiation Conclusion
	The SA negotiation concludes with the transmittal of the optional
	SA_COMMIT packet. This is determined by the setting of the SA Flags
	field. The SA_COMMIT message allows the initiating entity to inform the
	responding party that it has completed the processing required to set-up
	the SA and therefore, secure communications may begin. If the entity ini-
	tiating the SA establishment does not have the ability to queue incoming
	data it may receive prior to its completion of SA establishment process-
	ing, then it requires the responding entity to wait for an SA_COMMIT mes-
	sage before sending data. The transmittal of the ISA_COMMIT packet is op-
	tional and determined by the policy of the parties establishing the SA.
	All implementations MUST be able to generate, transmit, and receive this
	message.
	The ISA_COMMIT packet is the ISAKMP header, described in section 2.1, with
	no payload.
	3.4.1 SA Negotiation Conclusion Procedures
	When issuing an ISA_COMMIT packet, the initiating entity does the follow-
	ing:
	1. Construct an ISA_COMMIT packet (ISAKMP Header).
	2. Depending on the SA Attributes established in the SA initialization
	phase, apply the agreed upon security services.
	(a) If the SA requires authentication, the ISA_COMMIT packet is pro-
	cessed (or signed) and the signature placed as noted in Figure 1.
	(b) If the SA requires encryption and the encryption algorithm is a
	block encryption algorithm, then padding up to the block size
	MUST be placed as noted in Figure 1.
	(c) If the SA requires encryption, the ISA_COMMIT Signature is
	encrypted.
	3. Transmit the packet to the responding host as described in Section
	2.1.1.
	4. Clear all state and return to IDLE.
	When an ISA_COMMIT packet is received, the receiving entity does the fol-		1 2 3
	lowing:		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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ISAKMP Header ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Next Payload ! Payload Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Domain of Interpretation !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! !
			~ Situation ~
			! !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! !
			~ Proposal ~
			! !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	1. Check the ISAKMP header as described in section 2.1.1.		Figure 3: ISA_INIT_REQ and ISA_INIT_RESP Packet Format
	2. Depending on the SA Attributes, apply the agreed upon security		1 2 3
	services.		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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ISAKMP Header ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Next Payload ! Payload Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ~
			! Authentication Payload !
			~ ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Next Payload ! Payload Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ~
			! Key Exchange Payload !
			~ ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	(a) If the SA requires encryption, decrypt the ISA_COMMIT Signature.		Figure 4: ISA_AUTH&KE_REQ and ISA_AUTH&KE_RESP Packet Format
	If the decryption fails, the message is discarded and the		1 2 3
	following actions are taken:		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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Next Payload ! Payload Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Authentication Authority ! Reserved !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Authentication Type ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ~
			! Authentication Data !
			~ ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	i. The event, DECRYPTION FAILED, is logged in the appropriate		Figure 5: Authentication Payload Format
	system audit file.
	ii. Because the ISA_COMMIT packet is a unidirectional message a		1 2 3
	retransmission will not be performed. Because the SA is		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
	established, we recommend that communications can proceed,		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	however, the local security policy will dictate the		! Next Payload ! Payload Len ! RESERVED !
	procedures for continuing. We recommend that an ISA_NOTIFY		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	packet with an Error Message Type (see Section 6) be sent to		! KEI ! Length !
	the originator of the ISA_COMMIT packet.		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ~
			! Key Exchange Data !
			~ ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	(b) If the SA requires authentication, the ISA_COMMIT packet is		Figure 6: Key Exchange Payload Format
	processed and the calculated signature is compared to the
	signature contained in the ISA_COMMIT packet. If these signatures
	are not identical, the message is discarded and the following
	actions are taken:
	i. The event, INVALID SIGNATURE, is logged in the appropriate		o KEI (2 octets) - Key Exchange Identifier
	system audit file.
	ii. Because the ISA_COMMIT packet is a unidirectional message a		o Length (2 octets) - Length of payload in octets
	retransmission will not be performed. Because the SA is
	established, we recommend that communications can proceed,
	however, the local security policy will dictate the
	procedures for continuing. We recommend that an ISA_NOTIFY
	packet with an Error Message Type (see Section 6) be sent to
	the originator of the ISA_COMMIT packet.
	3. Clear all state and return to IDLE.		o Key Exchange Data (variable) - Data (i.e. public values) required to
			create session key.
	4 Security Association Modification		4 Security Association Modification
	Security Association modification provides the ability to update security		Security Association modification provides the ability to update security
	association attributes and parameters within an existing SA without having		association attributes and parameters within an existing SA without having
	to establish a new SA. The use of this exchange can provide performance		to establish a new SA. The use of this exchange can provide performance
	benefits without sacrificing the security of the existing communication.		benefits without sacrificing the security of the existing communication.
	The most common use of this exchange will be to re-key an existing SA.		The most common use of this exchange will be to re-key an existing SA.
	The format for the ISA_MODIFY packet is the same as the ISA_INIT_REQ and		The format for the ISA_MODIFY packet is the same as the ISA_INIT_REQ and
	ISA_INIT_RESP shown in Figure 4. All fields shown in Figure 4 exist for		ISA_INIT_RESP shown in Figure 3.
	the ISA_MODIFY packets.
	4.1 Modification Procedures		4.1 Modification Procedures
	The procedure for exchanging information to modify an SA are similiar to		The procedure for exchanging information to modify an SA are similiar to
	the SA negotiation exchange. The details of SA modification will be de-		the SA negotiation exchange. The details of SA modification will be de-
	scribed in this section as they are solidified during prototype develop-		scribed in this section as they are solidified during prototype develop-
	ment.		ment.
	5 Security Association Deletion		5 Security Association Deletion
	During communications it is possible that hosts may be compromised or that		During communications it is possible that hosts may be compromised or that
	information may be intercepted during transmission. Determining whether		information may be intercepted during transmission. Determining whether
	this has occurred is not an easy task and is outside the scope of this		this has occurred is not an easy task and is outside the scope of this
	Internet-Draft. However, if it is discovered that transmissions are being		Internet-Draft. However, if it is discovered that transmissions are being
	compromised, then it is necessary to delete the current SA and establish a		compromised, then it is necessary to delete the current SA and establish a
	new SA.		new SA.
	The ISA_DELETE packet (shown in Figure 8) provides a controlled method of		The ISA_DELETE packet (shown in Figure 7) provides a controlled method of
	informing a peer entity that the initiating entity has deleted an SA(s).		informing a peer entity that the initiating entity has deleted an SA(s).
	The ISA_DELETE packet allows for the deletion of any number of SAs with		The ISA_DELETE packet allows for the deletion of any number of SAs with
	a single message. The receiving entity SHOULD clean up its local SA		a single message. The receiving entity SHOULD clean up its local SA
	database. The receiving entity may be using the SA for secure communi-		database. The receiving entity may be using the SA for secure communi-
	cations with more than one party and would not want to actually delete the		cations with more than one party and would not want to actually delete the
	SA from its database in this case. However, upon receipt of an ISA_DELETE		SA from its database in this case. However, upon receipt of an ISA_DELETE
	packet the SAs listed in the SPIs field of the packet cannot be used with		packet the SAs listed in the SPIs field of the packet cannot be used with
	the initiating entity. The SA Establishment procedure must be invoked to		the initiating entity. The SA Establishment procedure must be invoked to
	re-establish secure communications.		re-establish secure communications.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ISAKMP Header ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! SPI Count ! Length !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~
	! SPIs !
	~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 8: SA Delete Payload Format
	o SPI Count - Number of security associations to be deleted		o SPI Count - Number of security associations to be deleted
	o Length - length of payload in octets		o Length - length of payload in octets
	o SPIs - Initiator's Security Parameter Index(s) to be deleted		o SPIs - Initiator's Security Parameter Index(s) to be deleted
	5.1 Deletion Procedures		5.1 Deletion Procedures
	When issuing an ISA_DELETE packet, the issuing entity (initiator or re-		When issuing an ISA_DELETE packet, the issuing entity (initiator or re-
	sponder) does the following:		sponder) does the following:
	1. Create initiator cookie. See Section 2.3.4 for details.		1. Create initiator cookie. See Section 2.3.7 for details.
	2. Determine SPI of receiving entity.		2. Determine SPI of receiving entity.
	3. Construct the ISA_DELETE packet.		3. Construct the ISA_DELETE packet.
	4. Depending on the SA Attributes, apply the agreed upon security		4. Depending on the SA Attributes, apply the agreed upon security
	services.		services.
	(a) If the SA requires authentication, the ISA_DELETE packet is		(a) If the SA requires authentication, the ISA_DELETE packet is
	processed and the signature placed as noted in Figure 1.		processed and the signature placed as noted in Figure 2.
	(b) If the SA requires encryption, the ISA_DELETE payload and		(b) If the SA requires encryption, the ISA_DELETE payload and
	Signature are encrypted.		Signature are encrypted.
	5. Transmit the packet to the destination host as described in Section		5. Transmit the packet to the destination host as described in Section
	2.1.1.		2.3.4.
	6. Update the local SA database to reflect the SPI deletions.		6. Update the local SA database to reflect the SPI deletions.
	Upon receipt of an ISA_DELETE packet, the receiving entity (initiator or		Upon receipt of an ISA_DELETE packet, the receiving entity (initiator or
	responder) does the following:		responder) does the following:
	1. Check the ISAKMP header as described in Section 2.1.1.		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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ISAKMP Header ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! SPI Count ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			~ ~
			! SPIs !
			~ ~
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 7: SA Delete Payload Format
			1. Check the ISAKMP header as described in Section 2.3.4.
	2. Depending on the SA Attributes, apply the agreed upon security		2. Depending on the SA Attributes, apply the agreed upon security
	services in the following order.		services in the following order.
	(a) If the SA requires encryption, decrypt the ISA_DELETE payload and		(a) If the SA requires encryption, decrypt the ISA_DELETE payload and
	Signature. If the decryption fails, the message is discarded and		Signature. If the decryption fails, the message is discarded and
	the following actions are taken:		the following actions are taken:
	i. The event is logged in the appropriate system audit file.		i. The event is logged in the appropriate system audit file.
	skipping to change at page 39, line 23 ¶		skipping to change at page 41, line 12 ¶
	4. Update the local SA database to reflect the SPI deletions.		4. Update the local SA database to reflect the SPI deletions.
	6 Notification Message		6 Notification Message
	The ISAKMP ISA_NOTIFY packet contains information one party wants to send		The ISAKMP ISA_NOTIFY packet contains information one party wants to send
	to another. Notification information can be error messages specifying		to another. Notification information can be error messages specifying
	why a SA could not be established. It can also be status data that a		why a SA could not be established. It can also be status data that a
	process managing an SA database wishes to communicate with a peer pro-		process managing an SA database wishes to communicate with a peer pro-
	cess. For example, a secure front end or security gateway may use the		cess. For example, a secure front end or security gateway may use the
	ISA_NOTIFY message to synchronize SA communication (see Appendix A.2).		ISA_NOTIFY message to synchronize SA communication (see Appendix B.2).
	The ISA_NOTIFY packet is unidirectional.		The ISA_NOTIFY packet is unidirectional.
	1 2 3		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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ISAKMP Header ~		~ ISAKMP Header ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	! Notify Message Type ! Length !		! Notify Message Type ! Length !
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	~ ~		~ ~
	! Notify Payload !		! Notify Payload !
	~ ~		~ ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 9: ISA NOTIFY Payload Format		Figure 8: ISA NOTIFY Payload Format
	o Notify Message Type (2 octets)		o Notify Message Type (2 octets)
	_Notification__Notify_Message_Type_		______Notification_______Notify_Message_Type__
	Error 1		RESERVED 0
	Status 2		Error 1-16383
			Reserved for Future Use 16384-32767
			Status 32768-49151
			DOI Specific 49152-65536
	o Length (2 octets) - length of payload in octets		o Length (2 octets) - length of payload in octets
	o Notify Payload (variable) - Value dependent on the Notify Message		o Notify Payload (variable) - Value dependent on the Notify Message
	Type		Type
	6.1 Notification Procedures		6.1 Notify Message Types
			Notify Messages - Errors Types
			__________Errors___________Value_Payload__
			DOI-NOT-SUPPORTED 1
			SITUATION-NOT-SUPPORTED 2
			INVALID-COOKIE 3
			INVALID-VERSION-NO 4
			INVALID-MESSAGE-TYPE 5
			INVALID-EXCHANGE-TYPE 6
			INVALID-SPI 7
			ATTRIBUTES-NOT-SUPPORTED 8
			NO-PROPOSAL-CHOOSEN 9
			BAD-PROPOSAL-SYNTAX 10
			ATTRIBUTES-NOT-SUPPORTED 11
			INVALID-SIGNATURE 12
			DECRYPTION-FAILED 13
			Notify Messages - Status Types
			__Status____Value____Payload____
			CONNECTED 32769
			6.2 Notification Procedures
	When issuing an ISA_NOTIFY message, the issuing entity (initiator or re-		When issuing an ISA_NOTIFY message, the issuing entity (initiator or re-
	sponder) does the following:		sponder) does the following:
	1. Create initiator cookie. See Section 2.3.4 for details.		1. Create initiator cookie. See Section 2.3.7 for details.
	2. Determine SPI of receiving entity.		2. Determine SPI of receiving entity.
	3. Construct ISA_NOTIFY packet.		3. Construct ISA_NOTIFY packet.
	4. Depending on the SA Attributes, apply the agreed upon security		4. Depending on the SA Attributes, apply the agreed upon security
	services.		services.
	(a) If the SA requires authentication, the ISA_NOTIFY packet is		(a) If the SA requires authentication, the ISA_NOTIFY packet is
	processed and the signature placed as noted in Figure 1.		processed and the signature placed as noted in Figure 2.
	(b) If the SA requires encryption, the ISA_NOTIFY payload and		(b) If the SA requires encryption, the ISA_NOTIFY payload and
	Signature are encrypted.		Signature are encrypted.
	5. Transmit the packet to the destination host as described in Section		5. Transmit the packet to the destination host as described in Section
	2.1.1.		2.3.4.
	Upon receipt of an ISA_NOTIFY message, the receiving entity (initiator or		Upon receipt of an ISA_NOTIFY message, the receiving entity (initiator or
	responder) does the following:		responder) does the following:
	1. Check the ISAKMP header as described in Section 2.1.1.		1. Check the ISAKMP header as described in Section 2.3.4.
	2. Depending on the SA Attributes, apply the agreed upon security		2. Depending on the SA Attributes, apply the agreed upon security
	services in the following order.		services in the following order.
	(a) If the SA requires encryption, decrypt the ISA_NOTIFY payload and		(a) If the SA requires encryption, decrypt the ISA_NOTIFY payload and
	Signature. If the decryption fails, the message is discarded and		Signature. If the decryption fails, the message is discarded and
	the following actions are taken:		the following actions are taken:
	i. The event is logged in the appropriate system audit file.		i. The event is logged in the appropriate system audit file.
	skipping to change at page 42, line 8 ¶		skipping to change at page 44, line 8 ¶
	policy will dictate the procedures for continuing.		policy will dictate the procedures for continuing.
	3. Unpack the ISA_NOTIFY payload.		3. Unpack the ISA_NOTIFY payload.
	4. Depending on the Notify Message Type, additional processing may be		4. Depending on the Notify Message Type, additional processing may be
	necessary.		necessary.
	7 Conclusions		7 Conclusions
	The Internet Security Association and Key Management Protocol (ISAKMP) is		The Internet Security Association and Key Management Protocol (ISAKMP) is
	a well designed protocol aimed at the Internet of the future. The massive		a well designed protocol aimed at the Internet of the future. The mas-
	growth of the Internet will lead to great diversity in network utiliza-		sive growth of the Internet will lead to great diversity in network uti-
	tion, communications, and security requirements. ISAKMP contains all the		lization, communications, security requirements, and security mechanisms.
	features that will be needed for this dynamic and expanding communications		ISAKMP contains all the features that will be needed for this dynamic and
	environment.		expanding communications environment.
	ISAKMP's Security Association (SA) feature coupled with authentication		ISAKMP's Security Association (SA) feature coupled with authentication
	and key establishment provides the security and flexibility that will be		and key establishment provides the security and flexibility that will be
	needed for future growth and diversity. This security diversity of multi-		needed for future growth and diversity. This security diversity of multi-
	ple key exchange techniques, encryption algorithms, authentication mecha-		ple key exchange techniques, encryption algorithms, authentication mecha-
	nisms, security services, and security attributes will allow users to se-		nisms, security services, and security attributes will allow users to se-
	lect the appropriate security for their network, communications, and secu-		lect the appropriate security for their network, communications, and secu-
	rity needs. The SA feature allows users to specify and negotiate security		rity needs. The SA feature allows users to specify and negotiate security
	requirements with other users. An additional benefit of supporting multi-		requirements with other users. An additional benefit of supporting multi-
	ple techniques in a single protocol is that as new techniques are devel-		ple techniques in a single protocol is that as new techniques are devel-
	skipping to change at page 43, line 5 ¶		skipping to change at page 45, line 5 ¶
	tion provides the assurance that the SAs and keys established are with the		tion provides the assurance that the SAs and keys established are with the
	desired party and not with an attacker.		desired party and not with an attacker.
	ISAKMP also follows good protocol design principles. Protocol specific		ISAKMP also follows good protocol design principles. Protocol specific
	information only is in the protocol header, following the design prin-		information only is in the protocol header, following the design prin-
	ciples of IPv6. The data transported by the protocol is separated into		ciples of IPv6. The data transported by the protocol is separated into
	functional payloads. As the Internet grows and evolves, new payloads to		functional payloads. As the Internet grows and evolves, new payloads to
	support new security functionality can be added without modifying the en-		support new security functionality can be added without modifying the en-
	tire protocol.		tire protocol.
	A ISAKMP Scenarios		A IP Security DOI
	Examples scenerios are are presented to help illustrate the ISAKMP's abil-		The IP Security DOI Assigned Number for IPv4 is one (1). The situation
	ity to support multiple authentication methods and key exchanges.		for DOI 1 is an IPv4 address. The IP Security DOI Assigned Number for
			IPv6 is two (2). The situation for DOI 2 is an IPv6 address.
	A.1 Initial ISAKMP Daemon Scenerio		A.1 IP Security Proposal Formats
	This example steps through two ISAKMP daemons establishing an SA between		This section defines the IP Security syntax for SA proposals and secu-
	themselves. This SA uses DNS Security Extentions [EK94] for authentica-		rity attributes. The SA proposals for a security protocol (i.e. ESP) are
	tion and a Photuris [Karn95] compliant key exchange. Following the SA es-		carried in an SA payload. The SA payload is sent in the following mes-
	tablishment between the daemons, SAs are established for ESP and AH commu-		sages: ISA_INIT_REQ, ISA_INIT_RESP, ISA_NEG_REQ, ISA_NEG_RESP, ISA_MOD_REQ,
	nications between user processes.		and
			ISA_MOD_RESP. This syntax groups the security attributes needed to perform
			a security function together. The proposal and attribute formats are de-
			fined so additions or modifications to the proposals or attributes do not
			require a modification to the protocol.
	1. The initiating daemon sends an ISA_INIT_REQ messages with ISAKMP SA #3,		Figure 9 shows the SA proposal format which contains the SA attributes.
	#2, and #1 (in priority order). These SAs are defined in C.1.1.		There can be one or more SA attribute in each SA proposal. There can one
			or more SA proposals sent for each security protocol, but only one re-
			sponse per security protocol is allowed. A negative response, such as:
			IMPROPER SA PROPOSAL FORMAT, is returned in an ISA_NOTIFY message.
	2. The responding daemon sends an ISA_INIT_RESP message indicating that		1 2 3
	ISAKMP SA #2 was selected, which requires DNS Signature and Key		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
	Records and a Photuris compliant key exchange [DOW92].		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Protocol # ! Proposal # ! Proposal Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! !
			+ +
			. .
			. SA Attributes .
			. .
			+ +
			! !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	3. The initiating daemon sends an ISA_KE_REQ packet with an index into		Figure 9: SA Proposal Format
	well-known table of generator / prime pairs and it's public value.
	4. Upon receipt of ISA_KE_REQ packet the responding daemon computes the		o Protocol Number (1 octet) - Identifies the security protocol
	shared secret and session key.		requiring the SA attributes proposed. Uses the same values as the
			IPv4 Protocol field [RFC-1700].
	5. The responding daemon sends an ISA_KE_RESP packet with an its public		o Proposal Number (1 octet) - Unique proposal identifier for the given
	value and both the initiator and responders public values signed		security protocol.
	using its Private (Signature) Key and encrypted in the session key
	created.
	6. Upon receipt of ISA_KE_REQ packet the initiating daemon computes the		o Proposal Length (1 octet) - Specifies the proposal length in 4-octet
	shared secret and session key.		units. Each IP Security proposal is an integer multiple of 4 octets
			long.
	7. The initiating daemon sends an ISA_AUTH_REQ packet with both the		o SA Attributes - Variable length field containing the attributes for
	initiator and responders public values signed using its Private		an SA.
	(Signature) Key and it's DNS name and Public (Verification) Key
	signed by it nameserver. All encrypted in the session key created.
	8. The responding daemon sends an ISA_AUTH_RESP packet with it's DNS name		Figure 10 shows the SA attribute format. The most significant bit of the
	and Public (Verification) signed by it Secure DNS nameserver and		Attribute Class defines a grouping of attributes within a proposal. The
	encrypted in the session key created.		second most significant bit indicates whether the attribute is of type
			basic or variable percision integer (VPI). Negative responses, such as:
			UNKNOWN SA ATTRIBUTE, are returned in an ISA_NOTIFY message.
	9. The initiating daemon sends an ISA_NEG_REQ packet with ESP SA #2, ESP		o Attribute Class (2 octets) - Unique identifier for each general class
	SA #1, AH SA #1, and AH SA #2. These SAs are defined in C.2.1.		of attribute type. ENCRYPTION ALGORITHM is an example of an
			attribute class. (See A.4 for the assigned attribute class values
			for ESP, AH, and Oakley.)
	10. The responding daemon sends an ISA_NEG_RESP packet indicating that ESP		The most significant bit (SET) of the Attribute Class is for indicating
	SA #2, and AH SA #1 was selected.		a grouping of attributes within a proposal. If the SET bit is one (1)
			the following attribute belongs with the current attribute. There can be
			two or more attributes in a group. If the SET bit is zero (0) either the
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!S!T! ! TYP=0 VPI Length !
			!E!Y! Attribute Class ! TYP=1 SA Attribute Value !
			!T!P! ! !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			. .
			. TYP=0 VPI Present .
			. .
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	A.2 Virtual Private Network Scenario		Figure 10: Attribute Format
	This scenario show how ISAKMP can be used in a Virtual Public Network		attribute is the last in a set or is an individual attribute. Attributes
			should be grouped together when a security policy decision must be made
			based on how attributes relate to each other, in addition to individual
			meaning.
			The second most significant bit (TYP) of the Attribute Class is for indi-
			cating whether the attribute is a basic type or a variable percision inte-
			ger (VPI). If the TYP bit is a zero (0) then the attribute is a VPI type.
			If the TYP bit is a one (1) then the attribute is a basic type.
			Figure 11 shows the basic SA attribute format and Figure 12 shows the VPI
			SA attribute format.
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!S!1! Attribute Class ! SA Attribute Value !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 11: Basic Attribute Format
			o Value (2 octets) - The value of the SA attribute as defined by the
			Attribute class. (See A.5 for the assigned attribute values for IP
			Security.)
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!S!0! Attribute Class ! VPI Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			. .
			. VPI .
			. .
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 12: VPI Attribute Format
			o VPI Length (2 octets) - Specifies the VPI's length in 4-octet units.
			Each VPI is an integer multiple of 4 octets long.
			o VPI - Variable Percision Integer. The field is aligned so the most
			significant bit is in the first 4-octet word following the VPI
			Length.
			A.2 ESP SA and AH SA Proposals
			The ESP and AH SAs are defined in [RFC-1825]. This section defines the
			format for the ESP and AH SA proposals. The attribute class fields are
			as they would appear in an ESP or AH SA Proposal. The attribute value and
			VPI fields contain examples of the information they would contain.
			Note: The Lifetime fields (Key and SA) can be either basic or VPI at-
			tributes. Therefore when parsing the Attribute Class, the TYP bit must
			always be checked.
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! AH ! Proposal # ! Proposal Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!1! Authentication Alg ! MD5 !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Authentication Mode ! KEYED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Auth Key Exch Id ! Oakley New Group Mode !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! Key Lifetime ! 1!
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Time (in seconds) !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! SA Lifetime ! 1!
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Time (in seconds) !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! IP Source Address(es) ! 1!
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! IPv4 Address !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Sensitivity Level ! SECRET !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 13: AH Proposal Format
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! ESP ! Proposal # ! Proposal Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!1! Encryption Algorithm ! DES !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Encryption Mode ! CBC !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Encryption Transform ! RFC-1828 !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Enc Key Exch Id ! Oakley EXTERNAL KEY MODE !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! Crypotgraphic Synch ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Replay Protection ! Present / Absent !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!1! Authentication Alg ! MD5 !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Authentication Mode ! KEYED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Auth Key Exch Id ! Oakley PRIVATE GROUP MODE !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Key Lifetime ! Time (in seconds) !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! SA Lifetime ! 1!
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Time (in seconds) !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! IP Source Address(es) ! 4!
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! IPv6 Address !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Sensitivity Level ! SECRET !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 14: ESP Proposal Format
			A.3 Oakley Proposal
			The Oakley proposal format contains the SA attributes that are exchanged
			in the ISA_INIT messages in order to establish the required security at-
			tributes for the key and authentication exchange. See [Oakley] for fur-
			ther details.
			Note: The three figures 15, 16, and 17 are all combine to make one pro-
			posal. They are shown seperately for reading and formatting ease.
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Oakley ! Proposal # ! Proposal Len ! RESERVED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! EHA Format !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! Group Format !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 15: Oakley Proposal Format
			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! Auth / Priv Flag ! PRIV !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Encryption Algorithm ! DES !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Hash Algorithm ! MD5 !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!1! Authentication Alg ! RSA !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!1! Authentication Mode ! KEYED !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 16: Oakley Proposal - EHA Format
			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
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!1! Group Description ! MODP !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Field Size ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Prime ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Generator1 ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Generator2 ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Curve-p1 ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Curve-p2 ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Largest Prime Factor ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!1!0! Order of Group ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			!0!0! Strength of Group ! Length !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			! MPI !
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Figure 17: Oakley Proposal - Group Format
			A.4 Attribute Class Assigned Numbers
			Values for attribute classes are specified in the most recent ``Assigned
			Numbers'' RFC [RFC-1700]. Presented in the following tables are the val-
			ues for ESP, AH, and Oakley SAs. In the Attribute Type Column, a ``B''
			means basic encoding and ``V'' mean Variable Percision Integer.
			AH and ESP Attribute Classes
			___________________Class_____________________Assigned_Value__Attribute_Type__
			RESERVED 0 x
			RESERVED 1 x
			Authentication Algorithm 2 B
			Authentication Mode 3 B
			Authentication KEI(s) 4 B
			Encryption Algorithm 5 B
			Encryption Mode 6 B
			Encryption Transform 7 B
			Encyption KEI(s) 8 B
			Size of cryptographic synchronization or IV 9 B/V
			Replay Protection 10 B
			Key Lifetime 11 B/V
			Rekey Value 12 B/V
			SA Lifetime 13 B/V
			IP Source Address(es) 14 V
			Sensitivity Level 15 B
			Oakley Attributes Classes
			__________________Class____________________Assigned_Value__Attribute_Type__
			Auth / Private Flag 16 B
			Hash Algorithm 17 B
			Group Description 18 B
			Group Type 19 B
			Field Element Size 20 V
			Print (P) or Irreducible Field Polynomial 21 V
			Generator (1 or 2 values) 22 V
			Curve Parameters (2 values) 23 V
			Largest Prime Factor of the Group Size 24 V
			Order of the Group 25 V
			Strength of Group 26 V
			Attribute class values 27-1024 are reserved for IANA Use. Attribute
			class values 1025-15360 are reserved for future use. Attribute class val-
			ues 15360-16384 are reserved for private use.
			A.5 Attribute Value Assigned Numbers
			A.5.1 Sensitivity Level Assigned Numbers
			Sensitivity Level
			_____Level_____Assigned_Value
			Not In Use 0
			Unclassified 1
			FOUO 2
			Undefined 3
			Confidential 4
			Secret 5
			Top Secret 6
			Sensitivity values 7-1024 are reserved for IANA Use. Values 1025-15360
			are reserved for future use. Values 15360-16384 are reserved for private
			use.
			A.5.2 Key Exchange Identifiers (KEI) Assigned Numbers
			Key Exchange Identifiers (KEI)
			_____Key_Exchange_____Assigned_Value_
			Reserved 0
			Oakley Main Mode 1
			Oakley ISAKMP Mode 2
			Oakley Quick Mode 3
			Oakley External Mode 4
			KEI values 5-1024 are reserved for IANA Use. Values 1025-15360 are re-
			served for future use. Values 15360-16384 are reserved for private use.
			A.5.3 Encryption Transform Assigned Numbers
			Encryption Transforms
			_____Transform_____Assigned_Value
			Reserved 0
			RFC-1829 1
			DES-CBC w/Replay 2
			Encryption Transform values 3-1024 are reserved for IANA Use. Values
			1025-15360 are reserved for future use. Values 15360-16384 are reserved
			for private use.
			B ISAKMP Scenarios
			Examples scenerios are are presented to help illustrate the ISAKMP's abil-
			ity to support multiple authentication methods and key exchanges.
			B.1 Oakley Scenario
			___________|_______________Oakley_Scenario_____________________________Entity
			N#1SI#1NTERNETNSE#2ntity #2
			_______|| _______||
			| | Establish Initial SA Between NSs| |
			| | | |
			| | ISA_INIT_REQ | |
			| | ============> | |
			| | ISA_INIT_RESP | |
			| | <============ | |
			| | | |
			| | Oakley Key Exchange Between NSs | |
			| | | |
			| | ISA_KE_REQ | |
			| | ==============> | |
			| | ISA_KE_RESP | |
			| | <=============== | |
			| | | |
			| | Oakley Authentication Exchange | |
			| | | |
			| | ISA_AUTH_REQ | |
			| | ==============> | |
			| | ISA_AUTH_RESP | |
			| | <=============== | |
			| | ISA_AUTH_REQ | |
			| | ==============> | |
			| | ISA_AUTH_RESP | |
			| | <=============== | |
			| | | |
			| | Protected Traffic | |
			| | NS#1 to NS#2 | |
			|_____|_ |______|
			___________|_________Oakley_Scenario_continued______________________EntityN#
			1SI#1NTERNETNSE#2ntity #2
			_______|| _______||
			| | SA Established NS#1 to NS#2 | |
			| | | |
			| |Establish SA Between Entities | |
			| | | |
			| | ISA_NEG_REQ | |
			| | ============> | |
			| | ISA_NEG_RESP | |
			| | <============ | |
			| | | |
			| | Oakley External Key Exchange | |
			| | Between Entities | |
			| | | |
			| | ISA_KE_REQ | |
			| | ==============> | |
			| | ISA_KE_RESP | |
			| | <=============== | |
			| | ISA_KE_REQ | |
			| | ==============> | |
			| | | |
			| | | |
			| | Protected Traffic | |
			| | Entity#1 to Entity#2 | |
			|______| <==============> |______|
			The diagrams above only shows ISAKMP messages exchanges. Shown are the
			exchanges to initiate SAs between entities and negotiation servers and
			the exchanges for the Oakley key exchange and authentication. The formats
			and contents of the messages can be found in [Oakley] and Appendix A. See
			Section 2.1 for the relationship of ISAKMP to the protocol stack.
			When an entity, which can be a process, application, security protocol,
			etc., wishes to establish communications with a peer entity a call is made
			to the negotiation server (NS). NS#1 checks the local security policy to
			determine if an SA is required. If an SA is required, then NS#1 checks
			if it has the appropriate SAs established with the peer NS (NS#2). If a
			negotiation SA (NS-to-NS SA) is exists, NS#1 can proceed to the start of
			the second diagram. If a negotiation SA needs to be established, the NSs
			exchange ISA_INIT messages to determine the security attributes, key ex-
			change, and authentication to be used for the negotiation SA. In our exam-
			ple the Oakley key exchange and authentication is choosen. The ISA_KE and
			ISA_AUTH messages are exchanged according to the rules defined in the key
			exchange. Oakley requires two key exchange messages and four authentica-
			tion messages. Once these exchanges are complete a negotiation SA between
			NSs is established. In the second diagram the negotiation SA is used to
			protect the remaining exchanges shown. The NSs now exchange ISA_NEG mes-
			sages to create a SA for the entity itself. In our example an Oakley Ex-
			ternal Key Exchange is now performed to establish a new key for the entity
			to entity SA. Once this SA is established, protected communications takes
			place.
			B.2 Virtual Private Network Scenario
			This scenario shows how ISAKMP can be used in a Virtual Public Network
	(VPN). The ability to establish SAs for more than just ESP and AH and one		(VPN). The ability to establish SAs for more than just ESP and AH and one
	of the uses of the ISA_NOTIFY message are also illustrated.		of the uses of the ISA_NOTIFY message are also illustrated.
	___________________________Virtual_Public_Network_Scenario_______________________		__________________|_________Virtual_Public_Network_Scenario____________________
	End System#1 SFE#1 INTERNET SFE#2 End System #2		____________EndSSystemF#1EI#1NTERNETSFEE#2nd System #2
	_______ _______		________|| ________||
	Establish ES#1 To | | | |		Establish ES#1 To | | | |
	SFE#1 Connection | | | |		SFE#1 Connection | | | |
	SYN | | | |		SYN | | | |
	===> | | | |		===> | | | |
	| |Establish Connection Between SFEs | |		| |Establish Connection Between SFEs | |
	| | | |		| | | |
	| | SYN | |		| | SYN | |
	| | ===> | |		| | ===> | |
	| | SYN, ACK | |		| | SYN, ACK | |
	| | <======= | |		| | <======= | |
	| | ACK | |		| | ACK | |
	| | ===> | |		| | ===> | |
	| | | |		| | | |
	| | Establish SA Between SFEs | |		| | Establish SA Between SFEs | |
	| | | |		| | | |
	| | ISA_INIT_REQ | |		| | ISA_INIT_REQ | |
	| | ============> | |		| | ============> | |
	| | ISA_INIT_RESP | |		| | ISA_INIT_RESP | |
	| | <============ | |		| | <============ | |
	| | ISA_KE&AUTH_REQ | |		| | ISA_KE&AUTH_REQ | |
	| | ==============> | |		| | ==============> | |
	| | ISA_KE&AUTH_RESP | |		| | ISA_KE&AUTH_RESP | |
	| | <=============== | |		| | <=============== | |
	| | Secure Connection | |Establish SFE#2		| | Secure Connection |
	| | Between SFEs | |to ES#2 Connection		|Establish SFE#2
			| | Between SFEs | |to ES#2
			Connection
	| | | |		| | | |
	| | | |SYN		| | | |SYN
	| | | |===>		| | | |===>
	| | | |SYN, ACK		| | | |SYN, ACK
	| | | |<=======		| | | |<=======
	| | | |ACK		| | | |ACK
	| | | |===>		| | | |===>
	| | ISA_NOTIFY(Status == Connected) | |		| | ISA_NOTIFY(Status == Connected) | |
	SYN, ACK | | <==================== | |		SYN, ACK | | <==================== | |
	<======= | | | |		<======= | | | |
	ACK | | | |		ACK | | | |
	===> | | | |		===> | | | |
	| | | |		| | | |
	| | Protected Traffic | |		| | Protected Traffic | |
	| | ES#1 to ES#2 | |		| | ES#1 to ES#2 | |
	|_______| <==============> |_______|		|_______| <==============> |_______|
	The diagram shows an End System (ES) using a connection oriented proto-		The diagram shows an End System (ES) using a connection oriented proto-
	col (we use TCP as an example) establishing a connection with another ES.		col (we use TCP as an example) establishing a connection with another ES.
	Both ES are behind Secure Front Ends (SFE) (e.g. firewalls). The connec-		Both ES are behind Secure Front Ends (SFE) (e.g. firewalls). The connec-
	tion establishment from End System #1 (ES#1) is intercepted by its Secure		tion establishment from End System #1 (ES#1) is intercepted by its Secure
	Front End (SFE #1). SFE#1 establishes a connection and then a Security		Front End (SFE #1). SFE#1 establishes a connection and then a Security
	Association (SA), using normal ISAKMP SA establishment procedures, with		Association (SA), using normal ISAKMP SA establishment procedures, with
	SFE #2. Next SFE #2 establishes a connection with ES #2. Upon successful		SFE #2. Next SFE #2 establishes a connection with ES #2. Upon successful
	completion SFE #2 sends an SA_NOTIFY with Status equal Connected. SFE #1		completion SFE #2 sends an ISA_NOTIFY with Status equal Connected. SFE #1
	completes it's connection with ES #1 and normal end to end communications		completes it's connection with ES #1 and normal end to end communications
	takes place secured between SFE #1 and SFE #2. If SFE #2 had been unable		takes place secured between SFE #1 and SFE #2. If SFE #2 had been unable
	to establish a connection with ES #2 it would have returned an SA_NOTIFY		to establish a connection with ES #2 it would have returned an ISA_NOTIFY
	with Status equal Not Connected with an optional reason code.		with Status equal Not Connected with an optional reason code.
	B Security Association Attributes		C Security Association Attributes
	This appendix contains a list of security attributes that should be con-		This appendix contains a list of security attributes that should be con-
	sidered when defining a Security Association (SA) for a security proto-		sidered when defining a Security Association (SA) for a security proto-
	col or application. As an example, the security attributes culled from		col or application. As an example, the security attributes culled from
	this list and required for an IP Security (AH, ESP) SA are defined in		this list and required for an IP Security (AH, ESP) SA are defined in
	[RFC-1825]. The separation of ISAKMP from a specific SA definition is im-		[RFC-1825]. The separation of ISAKMP from a specific SA definition is im-
	portant to ensure ISAKMP can establish SAs for all possible security func-		portant to ensure ISAKMP can establish SAs for all possible security func-
	tionality. Each security function will be required to maintain a database		tionality. Each security function will be required to maintain a database
	of current SAs. This list is based upon an e-mail message [Kent94] to the		of current SAs. This list is based upon an e-mail message [Kent94] to the
	IPSEC mail list from Steve Kent.		IPSEC mail list from Steve Kent.
	skipping to change at page 51, line 5 ¶		skipping to change at page 64, line 5 ¶
	i. ENABLE		i. ENABLE
	ii. PACKET-COUNT.INBOUND		ii. PACKET-COUNT.INBOUND
	iii. PACKET-COUNT.OUTBOUND		iii. PACKET-COUNT.OUTBOUND
	iv. TRIGGER.INBOUND		iv. TRIGGER.INBOUND
	v. TRIGGER.OUTBOUND		v. TRIGGER.OUTBOUND
	C Security Association Examples
	C.1 ISAKMP SA Definition
	The ISAKMP SA contains the SA attributes that are exchanged in the
	ISA_INIT messages.
	ISAKMP Security Association
	_______________________SA_Attributes_______________________Requirement__
	Peer ISAKMP Daemon Address REQUIRED
	Security Association Lifetime REQUIRED
	Certificate Authority REQUIRED
	Digital Signature Algorithm REQUIRED
	Signature Key(s) REQUIRED
	Security Association Lifetime REQUIRED
	Key Establishment Algorithm REQUIRED
	Cookie Generation Algorithm REQUIRED
	Sensitivity Level (e.g. Secret, Unclassified) RECOMMENDED
	Encryption Algorithm RECOMMENDED
	Encryption Mode RECOMMENDED
	Encryption Transform RECOMMENDED
	Encryption Key(s) RECOMMENDED
	Key Lifetime or Key Rollover RECOMMENDED
	Presence / Absence of cryptographic synchronization or IV RECOMMENDED
	Size of cryptographic synchronization or IV RECOMMENDED
	C.1.1 ISAKMP SA Examples
	ISAKMP SA #1
	_________________________SA_Class_________________________________SA_Type_________
	Peer ISAKMP Daemon Address N/A
	Security Association Lifetime 86400 seconds (1day)
	Certificate Authority DMS Root CAW
	Certificate Type X.509v1m
	Digital Signature Algorithm DSA
	Signature Key(s) N/A
	Security Association Lifetime 86400 seconds (1day)
	Key Establishment Algorithm Fortezza KEA
	Cookie Generation Algorithm SHA_1
	Sensitivity Level (e.g. Secret, Unclassified) Unclassified
	Encryption Algorithm Skipjack
	Encryption Mode CDC
	Encryption Transform NULL
	Encryption Key(s) N/A
	Key Lifetime or Key Rollover 3600 seconds (1 hour)
	Presence / Absence of cryptographic synchronization or IV Present
	Size of cryptographic synchronization or IV 64 bits
	ISAKMP SA #2
	_________________________SA_Class___________________________________SA_Type__________
	Peer ISAKMP Daemon Address N/A
	Security Association Lifetime 86400 seconds (1day)
	Certificate Authority DNSSEC janeway.ncsc.mil
	Certificate Type RR
	Digital Signature Algorithm RSA
	Signature Key(s) N/A
	Security Association Lifetime 86400 seconds (1day)
	Key Establishment Algorithm X9.42_STS
	Cookie Generation Algorithm MD5
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	Encryption Algorithm DES
	Encryption Mode CDC
	Encryption Transform RFC-1829
	Encryption Key(s) N/A
	Key Lifetime or Key Rollover 600 seconds (10 minutes)
	Presence / Absence of cryptographic synchronization or IV Present
	Size of cryptographic synchronization or IV 64 bits
	ISAKMP SA #3
	_________________________SA_Class___________________________________SA_Type__________
	Peer ISAKMP Daemon Address N/A
	Security Association Lifetime 86400 seconds (1day)
	Certificate Authority IPRA PCA UNINETT
	Certificate Type X.509v1
	Digital Signature Algorithm RSA
	Signature Key(s) N/A
	Security Association Lifetime 86400 seconds (1day)
	Key Establishment Algorithm STS
	Cookie Generation Algorithm MD5
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	Encryption Algorithm DES
	Encryption Mode CDC
	Encryption Transform RFC-1829
	Encryption Key(s) N/A
	Key Lifetime or Key Rollover 600 seconds (10 minutes)
	Presence / Absence of cryptographic synchronization or IV Present
	Size of cryptographic synchronization or IV 64 bits
	C.2 ESP SA and AH SA Definitions
	The following SAs are defined in [RFC-1825] and are presented here for
	comparative and completeness purposes.
	AH Security Association
	__________________SA_Attributes__________________Requirement_
	Authentication Algorithm REQUIRED
	Authentication Mode REQUIRED
	Authentication Key(s) REQUIRED
	Key Lifetime or Key Rollover RECOMMENDED
	Security Association Lifetime RECOMMENDED
	Sensitivity Level (e.g. Secret, Unclassified) RECOMMENDED
	ESP Security Association
	_______________________SA_Attributes_______________________Requirement__
	Encryption Algorithm REQUIRED
	Encryption Mode REQUIRED
	Encryption Transform REQUIRED
	Encryption Key(s) REQUIRED
	Presence / Absence of cryptographic synchronization or IV REQUIRED
	Size of cryptographic synchronization or IV REQUIRED
	Authentication Algorithm RECOMMENDED
	Authentication Mode RECOMMENDED
	Authentication Key(s) RECOMMENDED
	Key Lifetime or Key Rollover RECOMMENDED
	Security Association Lifetime RECOMMENDED
	Sensitivity Level (e.g. Secret, Unclassified) RECOMMENDED
	C.2.1 ESP and AH SA Examples
	AH SA #1
	____________________SA_Class_____________________________SA_Type__________
	Authentication Algorithm MD5
	Authentication Mode Keyed
	Authentication Key(s) Photuris
	Key Lifetime or Key Rollover 600 seconds (10 minutes)
	Security Association Lifetime 3600 seconds (1 hour)
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	AH SA #2
	____________________SA_Class_____________________________SA_Type__________
	Authentication Algorithm SHA
	Authentication Mode NULL
	Authentication Key(s) NULL
	Key Lifetime or Key Rollover 600 seconds (10 minutes)
	Security Association Lifetime 3600 seconds (1 hour)
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	ESP SA #1
	_________________________SA_Class___________________________________SA_Type__________
	Encryption Algorithm DES
	Encryption Mode CBC
	Encryption Transform RFC-1829
	Encryption Key(s) Phutoris Generated
	Presence / Absence of cryptographic synchronization or IV Present
	Size of cryptographic synchronization or IV 64 bits
	Authentication Algorithm NULL
	Authentication Mode NULL
	Authentication Key(s) NULL
	Key Lifetime or Key Rollover 600 seconds (10 minutes)
	Security Association Lifetime 3600 seconds (1 hour)
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	ESP SA #2
	_________________________SA_Class___________________________________SA_Type__________
	Encryption Algorithm DES
	Encryption Mode CBC
	Encryption Transform RFC-1829
	Encryption Key(s) X9.42_DH Generated
	Presence / Absence of cryptographic synchronization or IV Present
	Size of cryptographic synchronization or IV 64 bits
	Authentication Algorithm NULL
	Authentication Mode NULL
	Authentication Key(s) NULL
	Key Lifetime or Key Rollover 600 seconds (10 minutes)
	Security Association Lifetime 3600 seconds (1 hour)
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	C.2.2 Fortezza SA Examples
	Fortezza AH SA
	____________________SA_Class___________________________SA_Type________
	Authentication Algorithm SHA
	Authentication Mode NULL
	Authentication Key(s) DMS Root CAW
	Key Lifetime or Key Rollover 86400 seconds (1day)
	Security Association Lifetime 86400 seconds (1day)
	Sensitivity Level (e.g. Secret, Unclassified) N/A
	Fortezza ESP SA
	_________________________SA_Class__________________________________SA_Type_________
	Encryption Algorithm Skipjack
	Encryption Mode CBC
	Encryption Transform NULL
	Encryption Key(s) Fortezza KEA Generated
	Presence / Absence of cryptographic synchronization or IV Present
	Size of cryptographic synchronization or IV 64 bits
	Authentication Algorithm DSA
	Authentication Mode NULL
	Authentication Key(s) DMS Root CAW
	Key Lifetime or Key Rollover 3600 seconds (1 hour)
	Security Association Lifetime 86400 seconds (1day)
	Sensitivity Level (e.g. Secret, Unclassified) Unclassified
	Security Considerations		Security Considerations
	Cryptographic analysis techniques are improving at a steady pace. The		Cryptographic analysis techniques are improving at a steady pace. The
	continuing improvement in processing power makes once computational pro-		continuing improvement in processing power makes once computational pro-
	hibitive cryptographic attacks more realistic. New cryptographic algo-		hibitive cryptographic attacks more realistic. New cryptographic algo-
	rithms and public key generation techniques are also being developed at a		rithms and public key generation techniques are also being developed at a
	steady pace. New security services and mechanisms are being developed at		steady pace. New security services and mechanisms are being developed at
	an accelerated pace. A consistent method of choosing from a variety of		an accelerated pace. A consistent method of choosing from a variety of
	security services and mechanisms and to exchange attributes required by		security services and mechanisms and to exchange attributes required by
	the mechanisms is important to security in the complex structure of the		the mechanisms is important to security in the complex structure of the
	skipping to change at page 57, line 40 ¶		skipping to change at page 64, line 41 ¶
	[RFC-1825]. One bares repeating. Once a private session key is created		[RFC-1825]. One bares repeating. Once a private session key is created
	it must be safely stored. Failure to properly protect the private key		it must be safely stored. Failure to properly protect the private key
	from access both internal and external to the system completely nullifies		from access both internal and external to the system completely nullifies
	any protect provided by the IP Security services.		any protect provided by the IP Security services.
	Acknowledgements		Acknowledgements
	Marsha Gross, Bill Kutz, Mike Oehler, Mark Schneider, and Pete Sell pro-		Marsha Gross, Bill Kutz, Mike Oehler, Mark Schneider, and Pete Sell pro-
	vided significant input and review to this document.		vided significant input and review to this document.
			Scott Carlson ported the TIS DNSSEC prototype to FreeBSD for use with the
			ISAKMP prototype.
			Jeff Turner and Steve Smalley have contributed to the prototype develop-
			ment and integration with ESP and AH.
	Thanks to Carl Muckenhirn of SPARTA, Inc. for his assistance with LaTeX.		Thanks to Carl Muckenhirn of SPARTA, Inc. for his assistance with LaTeX.
	References		References
	[ANSI94] ANSI, X9.42: Public Key Cryptography for the Financial Services		[ANSI] ANSI, X9.42: Public Key Cryptography for the Financial Services
	Industry -- Establishment of Symmetric Algorithm Keys Using		Industry -- Establishment of Symmetric Algorithm Keys Using
	Diffie-Hellman, Working Draft, October 26, 1995.		Diffie-Hellman, Working Draft, October 26, 1995.
	[DOW92] W. Diffie, M.Wiener, P. Van Oorschot, Authtication and		[RFC-1825] Randall Atkinson, Security Architecture for the Internet
			Protocol, RFC-1825, August, 1995.
			[BC] Ballarie, A. and J. Crowcroft, Multicast-specific Security Threats
			and Countermeasures, Proceedings of 1995 ISOC Symposium on Networks
			& Distributed Systems Security, pp. 17-30, Internet Society, San
			Diego, CA, February 1995.
			[Berge] Berge, N.H., UNINETT PCA Policy Statements, Internet-Draft, work
			in progress, November, 1995.
			[DOW92] W. Diffie, M.Wiener, P. Van Oorschot, Authentication and
	Authenticated Key Exchanges, Designs, Codes, and Cryptography, 2,		Authenticated Key Exchanges, Designs, Codes, and Cryptography, 2,
	107-125, Kluwer Academic Publishers, 1992.		107-125, Kluwer Academic Publishers, 1992.
	[Berg] Berge, N.H., UNINETT PCA Policy Statements, Internet-Draft, work		[DNSSEC] Eastlake III, D. and C. Kaufman, Domain Name System Protocol
	in progress, November, 1995.		Security Extensions, Internet-Draft, work in progress, Feb, 1996.
	[EK94] Eastlake III, D. and C. Kaufman, Domain Name System Protocol		[Karn] Karn P. and B. Simpson, The Photuris Key Management Protocol,
	Security Extensions, Internet-Draft, work in progress, Oct, 1995.		Internet-Draft, work in progress, February, 1996.
	[Karn95] Karn P. and B. Simpson, The Photuris Key Management Protocol,		[RFC-1422] Steve Kent, Privacy Enhancement for Internet Electronic Mail:
	Internet-Draft, work in progress, November, 1995.		Part II: Certificate-Based Key Management, RFC-1422, February 1993.
	[Kent94] Steve Kent, IPSEC SMIB, e-mail to ipsec@ans.net, August 10,		[Kent94] Steve Kent, IPSEC SMIB, e-mail to ipsec@ans.net, August 10,
	1994.		1994.
	[RFC-1155] Rose M. and K. McCloghrie, Structure and Identification of
	Management Information for TCP/IP-based Internets, RFC-1155, May,
	1990.
	[RFC-1212] McCloghrie K. and M. Rose, Concise MIB Definitions, RFC-1212,		[RFC-1212] McCloghrie K. and M. Rose, Concise MIB Definitions, RFC-1212,
	March 26, 1991.		March 26, 1991.
	[RFC-1213] McCloghrie K. and M. Rose, Management Information Base for		[RFC-1213] McCloghrie K. and M. Rose, Management Information Base for
	Network Management of TCP/IP-based Internets: MIB-II, RFC-1213,		Network Management of TCP/IP-based Internets: MIB-II, RFC-1213,
	March 26, 1991.		March 26, 1991.
	[RFC-1422] Steve Kent, Privacy Enhancement for Internet Electronic Mail:		[Oakley] H. K. Orman, The Oakley Key Determination Protocol,
	Part II: Certificate-Based Key Management, RFC-1422, February 1993.		Internet-Draft, work in progress, February, 1996.
	[RFC-1825] Randell Atkinson, Security Architecture for the Internet		[RFC-1700] Reynolds, J. and J. Postel, Assigned Numbers, STD 2, RFC-1700,
	Protocol, RFC-1825, August, 1995.		October, 1994.
			[RFC-1155] Rose M. and K. McCloghrie, Structure and Identification of
			Management Information for TCP/IP-based Internets, RFC-1155, May,
			1990.
	[Secu] SECUREWARE INC., Peer Authentication and Key Management Protocol		[Secu] SECUREWARE INC., Peer Authentication and Key Management Protocol
	Specification, Version 2.2, October 27, 1995.		Specification, Version 2.2, October 27, 1995.
	[Schn94] Bruce Schneier, Applied Cryptography - Protocols, Algorithms,		[Schneier] Bruce Schneier, Applied Cryptography - Protocols, Algorithms,
	and Source Code in C, John Wiley & Sons, Inc., 1994.		and Source Code in C, John Wiley & Sons, Inc., 1994.
	[Spar94a] Harney H., C. Muckenhirn, and T. Rivers, Group Key Management		[Spar94a] Harney H., C. Muckenhirn, and T. Rivers, Group Key Management
	(GKMP) Architecture, SPARTA, Inc., Internet-Draft, September, 1994.		(GKMP) Architecture, SPARTA, Inc., Internet-Draft, September, 1994.
	[Spar94b] Harney H., C. Muckenhirn, and T. Rivers, Group Key Management		[Spar94b] Harney H., C. Muckenhirn, and T. Rivers, Group Key Management
	(GKMP) Specification, SPARTA, Inc., Internet-Draft, September, 1994.		(GKMP) Specification, SPARTA, Inc., Internet-Draft, September, 1994.
	Addresses of Authors		Addresses of Authors
End of changes. 161 change blocks.
	906 lines changed or deleted		1126 lines changed or added
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