< draft-ietf-ipsec-isakmp-08.txt   draft-ietf-ipsec-isakmp-09.txt >
IPSEC Working Group Douglas Maughan, Mark Schertler IPSEC Working Group Douglas Maughan, Mark Schertler
INTERNET-DRAFT Mark Schneider, Jeff Turner INTERNET-DRAFT Mark Schneider, Jeff Turner
draft-ietf-ipsec-isakmp-08.txt, .ps July 26, 1997 draft-ietf-ipsec-isakmp-09.txt, .ps March 10, 1998
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 9 skipping to change at page 3, line 9
abstracts.txt'' listing contained in the Internet- Drafts Shadow Di- abstracts.txt'' listing contained in the Internet- Drafts Shadow Di-
rectories on ds.internic.net (US East Coast), nic.nordu.net (Europe), rectories on ds.internic.net (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).
Distribution of this document is unlimited. Distribution of this document is unlimited.
Contents Contents
1 Introduction 6 1 Introduction 6
1.1 Requirements Terminology . . . . . . . . . . . . . . . . . . . . 7 1.1 Requirements Terminology . . . . . . . . . . . . . . . . . . . . 7
1.2 The Need for Negotiation . . . . . . . . . . . . . . . . . . . . 8 1.2 The Need for Negotiation . . . . . . . . . . . . . . . . . . . . 7
1.3 What can be Negotiated? . . . . . . . . . . . . . . . . . . . . . 8 1.3 What can be Negotiated? . . . . . . . . . . . . . . . . . . . . . 7
1.4 Security Associations and Management . . . . . . . . . . . . . . 9 1.4 Security Associations and Management . . . . . . . . . . . . . . 8
1.4.1Security Associations and Registration . . . . . . . . . . . . 9 1.4.1Security Associations and Registration . . . . . . . . . . . . 8
1.4.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 10 1.4.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 9
1.5 Authentication . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.5 Authentication . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5.1Certificate Authorities . . . . . . . . . . . . . . . . . . . 11 1.5.1Certificate Authorities . . . . . . . . . . . . . . . . . . . 10
1.5.2Entity Naming . . . . . . . . . . . . . . . . . . . . . . . . 11 1.5.2Entity Naming . . . . . . . . . . . . . . . . . . . . . . . . 10
1.5.3ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 11 1.5.3ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 11
1.6 Public Key Cryptography . . . . . . . . . . . . . . . . . . . . . 12 1.6 Public Key Cryptography . . . . . . . . . . . . . . . . . . . . . 12
1.6.1Key Exchange Properties . . . . . . . . . . . . . . . . . . . 13 1.6.1Key Exchange Properties . . . . . . . . . . . . . . . . . . . 12
1.6.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 14 1.6.2ISAKMP Requirements . . . . . . . . . . . . . . . . . . . . . 13
1.7 ISAKMP Protection . . . . . . . . . . . . . . . . . . . . . . . . 14 1.7 ISAKMP Protection . . . . . . . . . . . . . . . . . . . . . . . . 13
1.7.1Anti-Clogging (Denial of Service) . . . . . . . . . . . . . . 14 1.7.1Anti-Clogging (Denial of Service) . . . . . . . . . . . . . . 13
1.7.2Connection Hijacking . . . . . . . . . . . . . . . . . . . . . 14 1.7.2Connection Hijacking . . . . . . . . . . . . . . . . . . . . . 14
1.7.3Man-in-the-Middle Attacks . . . . . . . . . . . . . . . . . . 15 1.7.3Man-in-the-Middle Attacks . . . . . . . . . . . . . . . . . . 14
1.8 Multicast Communications . . . . . . . . . . . . . . . . . . . . 15 1.8 Multicast Communications . . . . . . . . . . . . . . . . . . . . 14
2 Terminology and Concepts 15 2 Terminology and Concepts 15
2.1 ISAKMP Terminology . . . . . . . . . . . . . . . . . . . . . . . 15 2.1 ISAKMP Terminology . . . . . . . . . . . . . . . . . . . . . . . 15
2.2 ISAKMP Placement . . . . . . . . . . . . . . . . . . . . . . . . 17 2.2 ISAKMP Placement . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3 Negotiation Phases . . . . . . . . . . . . . . . . . . . . . . . 18 2.3 Negotiation Phases . . . . . . . . . . . . . . . . . . . . . . . 18
2.4 Identifying Security Associations . . . . . . . . . . . . . . . . 19 2.4 Identifying Security Associations . . . . . . . . . . . . . . . . 19
2.5 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.5 Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.1Transport Protocol . . . . . . . . . . . . . . . . . . . . . . 21 2.5.1Transport Protocol . . . . . . . . . . . . . . . . . . . . . . 21
2.5.2RESERVED Fields . . . . . . . . . . . . . . . . . . . . . . . 21 2.5.2RESERVED Fields . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.3Anti-Clogging Token (``Cookie'') Creation . . . . . . . . . . 22 2.5.3Anti-Clogging Token (``Cookie'') Creation . . . . . . . . . . 21
3 ISAKMP Payloads 22 3 ISAKMP Payloads 22
3.1 ISAKMP Header Format . . . . . . . . . . . . . . . . . . . . . . 23 3.1 ISAKMP Header Format . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Payload Generic Header . . . . . . . . . . . . . . . . . . . . . 26 3.2 Generic Payload Header . . . . . . . . . . . . . . . . . . . . . 26
3.3 Data Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.3 Data Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4 Security Association Payload . . . . . . . . . . . . . . . . . . 28 3.4 Security Association Payload . . . . . . . . . . . . . . . . . . 27
3.5 Proposal Payload . . . . . . . . . . . . . . . . . . . . . . . . 29 3.5 Proposal Payload . . . . . . . . . . . . . . . . . . . . . . . . 29
3.6 Transform Payload . . . . . . . . . . . . . . . . . . . . . . . . 30 3.6 Transform Payload . . . . . . . . . . . . . . . . . . . . . . . . 30
3.7 Key Exchange Payload . . . . . . . . . . . . . . . . . . . . . . 31 3.7 Key Exchange Payload . . . . . . . . . . . . . . . . . . . . . . 31
3.8 Identification Payload . . . . . . . . . . . . . . . . . . . . . 32 3.8 Identification Payload . . . . . . . . . . . . . . . . . . . . . 32
3.9 Certificate Payload . . . . . . . . . . . . . . . . . . . . . . . 33 3.9 Certificate Payload . . . . . . . . . . . . . . . . . . . . . . . 33
3.10Certificate Request Payload . . . . . . . . . . . . . . . . . . . 35 3.10Certificate Request Payload . . . . . . . . . . . . . . . . . . . 35
3.11Hash Payload . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.11Hash Payload . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.12Signature Payload . . . . . . . . . . . . . . . . . . . . . . . . 37 3.12Signature Payload . . . . . . . . . . . . . . . . . . . . . . . . 37
3.13Nonce Payload . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.13Nonce Payload . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.14Notification Payload . . . . . . . . . . . . . . . . . . . . . . 38 3.14Notification Payload . . . . . . . . . . . . . . . . . . . . . . 38
3.14.1Notify Message Types . . . . . . . . . . . . . . . . . . . . . 40 3.14.1Notify Message Types . . . . . . . . . . . . . . . . . . . . . 40
3.15Delete Payload . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.15Delete Payload . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.16Vendor ID Payload . . . . . . . . . . . . . . . . . . . . . . . . 43
4 ISAKMP Exchanges 43 4 ISAKMP Exchanges 45
4.1 Security Association Establishment . . . . . . . . . . . . . . . 43 4.1 ISAKMP Exchange Types . . . . . . . . . . . . . . . . . . . . . . 45
4.1.1Security Association Establishment Examples . . . . . . . . . 45 4.1.1Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.2 Security Association Modification . . . . . . . . . . . . . . . . 47 4.2 Security Association Establishment . . . . . . . . . . . . . . . 46
4.3 ISAKMP Exchange Types . . . . . . . . . . . . . . . . . . . . . . 48 4.2.1Security Association Establishment Examples . . . . . . . . . 48
4.3.1Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4.3 Security Association Modification . . . . . . . . . . . . . . . . 50
4.4 Base Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.4 Base Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.5 Identity Protection Exchange . . . . . . . . . . . . . . . . . . 50 4.5 Identity Protection Exchange . . . . . . . . . . . . . . . . . . 52
4.6 Authentication Only Exchange . . . . . . . . . . . . . . . . . . 51 4.6 Authentication Only Exchange . . . . . . . . . . . . . . . . . . 53
4.7 Aggressive Exchange . . . . . . . . . . . . . . . . . . . . . . . 53 4.7 Aggressive Exchange . . . . . . . . . . . . . . . . . . . . . . . 54
4.8 Informational Exchange . . . . . . . . . . . . . . . . . . . . . 54 4.8 Informational Exchange . . . . . . . . . . . . . . . . . . . . . 56
5 ISAKMP Payload Processing 54 5 ISAKMP Payload Processing 56
5.1 General Message Processing . . . . . . . . . . . . . . . . . . . 55 5.1 General Message Processing . . . . . . . . . . . . . . . . . . . 57
5.2 ISAKMP Header Processing . . . . . . . . . . . . . . . . . . . . 55 5.2 ISAKMP Header Processing . . . . . . . . . . . . . . . . . . . . 57
5.3 Generic Payload Header Processing . . . . . . . . . . . . . . . . 57 5.3 Generic Payload Header Processing . . . . . . . . . . . . . . . . 59
5.4 Security Association Payload Processing . . . . . . . . . . . . . 58 5.4 Security Association Payload Processing . . . . . . . . . . . . . 60
5.4.1Proposal Payload Processing . . . . . . . . . . . . . . . . . 60 5.5 Proposal Payload Processing . . . . . . . . . . . . . . . . . . . 62
5.4.2Transform Payload Processing . . . . . . . . . . . . . . . . . 61 5.6 Transform Payload Processing . . . . . . . . . . . . . . . . . . 63
5.5 Key Exchange Payload Processing . . . . . . . . . . . . . . . . . 62 5.7 Key Exchange Payload Processing . . . . . . . . . . . . . . . . . 64
5.6 Identification Payload Processing . . . . . . . . . . . . . . . . 63 5.8 Identification Payload Processing . . . . . . . . . . . . . . . . 65
5.7 Certificate Payload Processing . . . . . . . . . . . . . . . . . 63 5.9 Certificate Payload Processing . . . . . . . . . . . . . . . . . 66
5.8 Certificate Request Payload Processing . . . . . . . . . . . . . 64 5.10Certificate Request Payload Processing . . . . . . . . . . . . . 67
5.9 Hash Payload Processing . . . . . . . . . . . . . . . . . . . . . 66 5.11Hash Payload Processing . . . . . . . . . . . . . . . . . . . . . 68
5.10Signature Payload Processing . . . . . . . . . . . . . . . . . . 67 5.12Signature Payload Processing . . . . . . . . . . . . . . . . . . 69
5.11Nonce Payload Processing . . . . . . . . . . . . . . . . . . . . 68 5.13Nonce Payload Processing . . . . . . . . . . . . . . . . . . . . 70
5.12Notification Payload Processing . . . . . . . . . . . . . . . . . 68 5.14Notification Payload Processing . . . . . . . . . . . . . . . . . 71
5.13Delete Payload Processing . . . . . . . . . . . . . . . . . . . . 70 5.15Delete Payload Processing . . . . . . . . . . . . . . . . . . . . 73
6 Conclusions 73 6 Conclusions 75
A ISAKMP Security Association Attributes 74 A ISAKMP Security Association Attributes 76
A.1 Background/Rationale . . . . . . . . . . . . . . . . . . . . . . 74 A.1 Background/Rationale . . . . . . . . . . . . . . . . . . . . . . 76
A.2 Assigned Values for the Internet IP Security DOI . . . . . . . . 74 A.2 Internet IP Security DOI Assigned Value . . . . . . . . . . . . . 76
A.2.1Internet IP Security DOI Assigned Value . . . . . . . . . . . 74 A.3 Supported Security Protocols . . . . . . . . . . . . . . . . . . 76
A.2.2Supported Security Protocols . . . . . . . . . . . . . . . . . 74 A.4 ISAKMP Identification Type Values . . . . . . . . . . . . . . . . 77
B Defining a new Domain of Interpretation 76 A.4.1ID_IPV4_ADDR . . . . . . . . . . . . . . . . . . . . . . . . . 77
B.1 Situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 A.4.2ID_IPV4_ADDR_SUBNET . . . . . . . . . . . . . . . . . . . . . . 77
B.2 Security Policies . . . . . . . . . . . . . . . . . . . . . . . . 77 A.4.3ID_IPV6_ADDR . . . . . . . . . . . . . . . . . . . . . . . . . 77
B.3 Naming Schemes . . . . . . . . . . . . . . . . . . . . . . . . . 77 A.4.4ID_IPV6_ADDR_SUBNET . . . . . . . . . . . . . . . . . . . . . . 77
B.4 Syntax for Specifying Security Services . . . . . . . . . . . . . 77 B Defining a new Domain of Interpretation 78
B.5 Payload Specification . . . . . . . . . . . . . . . . . . . . . . 77 B.1 Situation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
B.6 Defining new Exchange Types . . . . . . . . . . . . . . . . . . . 77 B.2 Security Policies . . . . . . . . . . . . . . . . . . . . . . . . 79
B.3 Naming Schemes . . . . . . . . . . . . . . . . . . . . . . . . . 79
B.4 Syntax for Specifying Security Services . . . . . . . . . . . . . 79
B.5 Payload Specification . . . . . . . . . . . . . . . . . . . . . . 79
B.6 Defining new Exchange Types . . . . . . . . . . . . . . . . . . . 79
List of Figures List of Figures
1 ISAKMP Relationships . . . . . . . . . . . . . . . . . . . . . . 18 1 ISAKMP Relationships . . . . . . . . . . . . . . . . . . . . . . 17
2 ISAKMP Header Format . . . . . . . . . . . . . . . . . . . . . . 23 2 ISAKMP Header Format . . . . . . . . . . . . . . . . . . . . . . 23
3 Generic Payload Header . . . . . . . . . . . . . . . . . . . . . 26 3 Generic Payload Header . . . . . . . . . . . . . . . . . . . . . 26
4 Data Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Data Attributes . . . . . . . . . . . . . . . . . . . . . . . . . 27
5 Security Association Payload . . . . . . . . . . . . . . . . . . 28 5 Security Association Payload . . . . . . . . . . . . . . . . . . 28
6 Proposal Payload Format . . . . . . . . . . . . . . . . . . . . . 29 6 Proposal Payload Format . . . . . . . . . . . . . . . . . . . . . 29
7 Transform Payload Format . . . . . . . . . . . . . . . . . . . . 30 7 Transform Payload Format . . . . . . . . . . . . . . . . . . . . 30
8 Key Exchange Payload Format . . . . . . . . . . . . . . . . . . . 32 8 Key Exchange Payload Format . . . . . . . . . . . . . . . . . . . 32
9 Identification Payload Format . . . . . . . . . . . . . . . . . . 33 9 Identification Payload Format . . . . . . . . . . . . . . . . . . 33
10 Certificate Payload Format . . . . . . . . . . . . . . . . . . . 34 10 Certificate Payload Format . . . . . . . . . . . . . . . . . . . 34
11 Certificate Request Payload Format . . . . . . . . . . . . . . . 35 11 Certificate Request Payload Format . . . . . . . . . . . . . . . 35
12 Hash Payload Format . . . . . . . . . . . . . . . . . . . . . . . 36 12 Hash Payload Format . . . . . . . . . . . . . . . . . . . . . . . 36
13 Signature Payload Format . . . . . . . . . . . . . . . . . . . . 37 13 Signature Payload Format . . . . . . . . . . . . . . . . . . . . 37
14 Nonce Payload Format . . . . . . . . . . . . . . . . . . . . . . 38 14 Nonce Payload Format . . . . . . . . . . . . . . . . . . . . . . 38
15 Notification Payload Format . . . . . . . . . . . . . . . . . . . 39 15 Notification Payload Format . . . . . . . . . . . . . . . . . . . 39
16 Delete Payload Format . . . . . . . . . . . . . . . . . . . . . . 42 16 Delete Payload Format . . . . . . . . . . . . . . . . . . . . . . 42
17 Vendor ID Payload Format . . . . . . . . . . . . . . . . . . . . 44
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. the Internet.
The Internet Security Association and Key Management Protocol (ISAKMP) de- The Internet Security Association and Key Management Protocol (ISAKMP) de-
skipping to change at page 7, line 10 skipping to change at page 7, line 10
gether as exchange types to establish security associations and perform gether as exchange types to establish security associations and perform
key exchanges in an authenticated manner. Additionally, security as- key exchanges in an authenticated manner. Additionally, security as-
sociation modification, deletion, and error notification are discussed. sociation modification, deletion, and error notification are discussed.
Section 5 describes the processing of each payload within the context of Section 5 describes the processing of each payload within the context of
ISAKMP exchanges, including error handling and associated actions. The ISAKMP exchanges, including error handling and associated actions. The
appendices provide the attribute values necessary for ISAKMP and require- appendices provide the attribute values necessary for ISAKMP and require-
ment for defining a new Domain of Interpretation (DOI) within ISAKMP. ment for defining a new Domain of Interpretation (DOI) within ISAKMP.
1.1 Requirements Terminology 1.1 Requirements Terminology
In this document, the words that are used to define the significance of The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD
each particular requirement are usually capitalised. These words are: NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document,
are to be interpreted as described in [RFC-2119].
- MUST
This word or the adjective "REQUIRED" means that implementation of
the item is an absolute requirement of the specification.
- MUST NOT
This phrase means that the definition is an absolute prohibition
of the specification.
- SHOULD
This word or the adjective "RECOMMENDED" means that there might
exist valid reasons in particular circumstances to not implement
this item, but the full implications should be understood and the
case carefully weighed before not implementing this or not
implementing in a conforming manner.
- MAY
This word or the adjective "OPTIONAL" means that implementation of
this item is truly optional. One vendor might choose to include
the item because particular buyers require it or it enhances the
product, while another vendor may omit the same item.
- CONFORMANCE and COMPLIANCE
Conformance to this specification has the same meaning as
compliance to this specification. In either case, the
mandatory-to-implement, or MUST, items MUST be fully implemented
as specified here. If any mandatory item is not implemented as
specified here, that implementation is not conforming and not
compliant with this specification.
1.2 The Need for Negotiation 1.2 The Need for Negotiation
ISAKMP extends the assertion in [DOW92] that authentication and key ex- ISAKMP extends the assertion in [DOW92] that authentication and key ex-
changes must be combined for better security to include security associa- changes must be combined for better security to include security associa-
tion exchanges. The security services required for communications depends tion exchanges. The security services required for communications depends
on the individual network configurations and environments. Organizations on the individual network configurations and environments. Organizations
are setting up Virtual Private Networks (VPN), also known as Intranets, are setting up Virtual Private Networks (VPN), also known as Intranets,
that will require one set of security functions for communications within that will require one set of security functions for communications within
the VPN and possibly many different security functions for communications the VPN and possibly many different security functions for communications
skipping to change at page 10, line 17 skipping to change at page 9, line 27
Security Association (SA) establishment MUST be part of the key manage- Security Association (SA) establishment MUST be part of the key manage-
ment protocol defined for IP based networks. The SA concept is required ment protocol defined for IP based networks. The SA concept is required
to support security protocols in a diverse and dynamic networking envi- to support security protocols in a diverse and dynamic networking envi-
ronment. Just as authentication and key exchange must be linked to pro- ronment. Just as authentication and key exchange must be linked to pro-
vide assurance that the key is established with the authenticated party vide assurance that the key is established with the authenticated party
[DOW92], SA establishment must be linked with the authentication and the [DOW92], SA establishment must be linked with the authentication and the
key exchange protocol. key exchange protocol.
ISAKMP provides the protocol exchanges to establish a security association ISAKMP provides the protocol exchanges to establish a security association
between negotiating entities followed by the establishment of a security between negotiating entities followed by the establishment of a security
association by these negotiated entities in behalf of some protocol (e.g. association by these negotiating entities in behalf of some protocol (e.g.
ESP/AH). First, an initial protocol exchange allows a basic set of secu- ESP/AH). First, an initial protocol exchange allows a basic set of secu-
rity attributes to be agreed upon. This basic set provides protection for rity attributes to be agreed upon. This basic set provides protection for
subsequent ISAKMP exchanges. It also indicates the authentication method subsequent ISAKMP exchanges. It also indicates the authentication method
and key exchange that will be performed as part of the ISAKMP protocol. and key exchange that will be performed as part of the ISAKMP protocol.
If a basic set of security attributes is already in place between the ne- If a basic set of security attributes is already in place between the ne-
gotiating server entities, the initial ISAKMP exchange may be skipped and gotiating server entities, the initial ISAKMP exchange may be skipped and
the establishment of a security association can be done directly. After the establishment of a security association can be done directly. After
the basic set of security attributes has been agreed upon, initial iden- the basic set of security attributes has been agreed upon, initial iden-
tity authenticated, and required keys generated, the established SA can tity authenticated, and required keys generated, the established SA can
be used for subsequent communications by the entity that invoked ISAKMP. be used for subsequent communications by the entity that invoked ISAKMP.
The basic set of SA attributes that MUST be implemented to provide ISAKMP The basic set of SA attributes that MUST be implemented to provide ISAKMP
interoperability are defined in Appendix A. interoperability are defined in Appendix A.
1.5 Authentication 1.5 Authentication
A very important step in establishing secure network communications is au- A very important step in establishing secure network communications is au-
thentication of the entity at the other end of the communication. Many thentication of the entity at the other end of the communication. Many
authentication mechanisms are available. Authentication mechanisms fall authentication mechanisms are available. Authentication mechanisms fall
into two catagories of strength - weak and strong. Passwords are an ex- into two catagories of strength - weak and strong. Sending cleartext keys
ample of a mechanism that provides weak authentication. The reason pass- or other unprotected authenticating information over a network is weak,
words are considered weak is the fact that most users pick passwords that due to the threat of reading them with a network sniffer. Additionally,
are easy to guess and when used over an unprotected network are easily sending one-way hashed poorly-chosen keys with low entropy is also weak,
read by network sniffers. Digital signatures, such as the Digital Sig- due to the threat of brute-force guessing attacks on the sniffed mes-
nature Standard (DSS) and the Rivest-Shamir-Adleman (RSA) signature, are sages. While passwords can be used for establishing identity, they are
public key based strong authentication mechanisms. When using public not considered in this context because of recent statements from the In-
key digital signatures each entity requires a public key and a private ternet Architecture Board [IAB]. Digital signatures, such as the Digital
key. Certificates are an essential part of a digital signature authen- Signature Standard (DSS) and the Rivest-Shamir-Adleman (RSA) signature,
tication mechanism. Certificates bind a specific entity's identity (be are public key based strong authentication mechanisms. When using pub-
it host, network, user, or application) to its public keys and possi- lic key digital signatures each entity requires a public key and a pri-
bly other security-related information such as privileges, clearances, vate key. Certificates are an essential part of a digital signature au-
thentication mechanism. Certificates bind a specific entity's identity
(be it host, network, user, or application) to its public keys and pos-
sibly other security-related information such as privileges, clearances,
and compartments. Authentication based on digital signatures requires a and compartments. Authentication based on digital signatures requires a
trusted third party or certificate authority to create, sign and properly trusted third party or certificate authority to create, sign and properly
distribute certificates. For more detailed information on digital signa- distribute certificates. For more detailed information on digital signa-
tures, such as DSS and RSA, and certificates see [Schneier]. tures, such as DSS and RSA, and certificates see [Schneier].
1.5.1 Certificate Authorities 1.5.1 Certificate Authorities
Certificates require an infrastructure for generation, verification, re- Certificates require an infrastructure for generation, verification, re-
vocation, management and distribution. The Internet Policy Registration vocation, management and distribution. The Internet Policy Registration
Authority (IPRA) [RFC-1422] has been established to direct this infras- Authority (IPRA) [RFC-1422] has been established to direct this infras-
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1.5.2 Entity Naming 1.5.2 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 [Berge] 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 associated 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 usually the entity's e-mail address which has meaning to PGP the name is usually the entity's e-mail address which has meaning to
those, and only those, who understand e-mail. Another web of trust could those, and only those, who understand e-mail. Another web of trust could
use an entirely different naming scheme. use an entirely different naming scheme.
1.5.3 ISAKMP Requirements 1.5.3 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, which makes access control
questionable. While encryption (e.g. ESP) and integrity (e.g. AH) will questionable. While encryption (e.g. ESP) and integrity (e.g. AH) will
protect subsequent communications from passive eavesdroppers, without au- protect subsequent communications from passive eavesdroppers, without au-
thentication it is possible that the SA and key may have been established thentication it is possible that the SA and key may have been established
with an adversary who performed an active man-in-the-middle attack and is with an adversary who performed an active man-in-the-middle attack and is
now stealing all your personal data. now stealing all your personal 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 signature algo- component. However, ISAKMP does not mandate a specific signature algo-
rithm or certificate authority (CA). ISAKMP allows an entity initiating rithm or certificate authority (CA). ISAKMP allows an entity initiating
communications to indicate which CAs it supports. After selection of a communications to indicate which CAs it supports. After selection of a
CA, the protocol provides the messages required to support the actual au- CA, the protocol provides the messages required to support the actual au-
thentication exchange. The protocol provides a facility for identifica- thentication exchange. The protocol provides a facility for identifica-
tion of different certificate authorities, certificate types (e.g. X.509, tion of different certificate authorities, certificate types (e.g. X.509,
PKCS #7, PGP, DNS SIG and KEY records), and the exchange of the certifi- PKCS #7, PGP, DNS SIG and KEY records), and the exchange of the certifi-
cates identified. cates identified.
ISAKMP utilizes digital signatures, based on public cryptography, for au- ISAKMP utilizes digital signatures, based on public key cryptography, for
thentication. There are other strong authentication systems available, authentication. 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
its network domain. A client's proof that it holds its secret key pro- its network domain. A client's proof that it holds its secret key pro-
vides authenticaton to a server. vides authenticaton to a server.
The ISAKMP specification does not specify the protocol for communicating The ISAKMP specification does not specify the protocol for communicating
with the trusted third parties (TTP) or certificate directory services. with the trusted third parties (TTP) or certificate directory services.
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include the key establishment method, authentication, symmetry, perfect include the key establishment method, authentication, symmetry, perfect
forward secrecy, and back traffic protection. forward secrecy, and back traffic protection.
NOTE: Cryptographic keys can protect information for a considerable length NOTE: Cryptographic keys can protect information for a considerable length
of time. However, this is based on the assumption that keys used for pro- of time. However, this is based on the assumption that keys used for pro-
tection of communications are destroyed after use and not kept for any tection of communications are destroyed after use and not kept for any
reason. reason.
1.6.1 Key Exchange Properties 1.6.1 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 than the following method. The Diffie-Hellman (D-H) algorithm il- head than the following method. The Diffie-Hellman (D-H) algorithm il-
lustrates key generation using public key cryptography. The D-H algorithm lustrates key generation using public key cryptography. The D-H algorithm
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can be used as a session key or as a key encryption key for encrypting a can be used as a session key or as a key encryption key for encrypting a
randomly generated session key. This method generates a session key based randomly generated session key. This method generates a session key based
on public and secret information held by both users. The benefit of the on public and secret information held by both users. The benefit of the
D-H algorithm is that the key used for encrypting messages is based on D-H algorithm is that the key used for encrypting messages is based on
information held by both users and the independence of keys from one key information held by both users and the independence of keys from one key
exchange to another provides perfect forward secrecy. Detailed descrip- exchange to another provides perfect forward secrecy. Detailed descrip-
tions of these algorithms can be found in [Schneier]. There are a number tions of these algorithms can be found in [Schneier]. There are a number
of variations on these two key generation schemes and these variations do of variations on these two key generation schemes and these variations do
not necessarily interoperate. 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 provided 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
initiate the exchange and exchanged messages can cross in transit with- can initiate the exchange and exchanged messages can cross in transit
out affecting the key that is generated. This is desirable so that com- without affecting the key that is generated. This is desirable so that
putation of the keys does not require either party to know who initiated computation of the keys does not require either party to know who initi-
the exchange. While key exchange symmetry is desirable, symmetry in the ated the exchange. While key exchange symmetry is desirable, symmetry in
entire key management protocol may provide a vulnerablity to reflection the entire key management protocol may provide a vulnerablity to reflec-
attacks. tion attacks.
Perfect Forward Secrecy As described in [DOW92], an authenticated key ex- Perfect Forward Secrecy: As described in [DOW92], an authenticated key ex-
change protocol provides perfect forward secrecy if disclosure of long- change protocol provides perfect forward secrecy if disclosure of long-
term secret keying material does not compromise the secrecy of the ex- term secret keying material does not compromise the secrecy of the ex-
changed keys from previous communications. The property of perfect for- changed keys from previous communications. The property of perfect for-
ward secrecy does not apply to key exchange without authentication. ward secrecy does not apply to key exchange without authentication.
1.6.2 ISAKMP Requirements 1.6.2 ISAKMP Requirements
An authenticated key exchange MUST be supported by ISAKMP. Users SHOULD An authenticated key exchange MUST be supported by ISAKMP. Users SHOULD
choose additional key establishment algorithms based on their require- choose additional key establishment algorithms based on their require-
ments. ISAKMP does not specify a specific key exchange. However, ments. ISAKMP does not specify a specific key exchange. However, [IKE]
[IO-Res] describes a proposal for using the Oakley key exchange [Oakley] describes a proposal for using the Oakley key exchange [Oakley] in con-
in conjunction with ISAKMP. Requirements that should be evaluated when junction with ISAKMP. Requirements that should be evaluated when choosing
choosing a key establishment algorithm include establishment method (gen- a key establishment algorithm include establishment method (generation vs.
eration vs. transport), perfect forward secrecy, computational overhead, transport), perfect forward secrecy, computational overhead, key escrow,
key escrow, and key strength. Based on user requirements, ISAKMP allows and key strength. Based on user requirements, ISAKMP allows an entity
an entity initiating communications to indicate which key exchanges it initiating communications to indicate which key exchanges it supports.
supports. After selection of a key exchange, the protocol provides the After selection of a key exchange, the protocol provides the messages re-
messages required to support the actual key establishment. quired to support the actual key establishment.
1.7 ISAKMP Protection 1.7 ISAKMP Protection
1.7.1 Anti-Clogging (Denial of Service) 1.7.1 Anti-Clogging (Denial of Service)
Of the numerous security services available, protection against denial Of the numerous security services available, protection against denial
of service always seems to be one of the most difficult to address. A of service always seems to be one of the most difficult to address. A
``cookie'' or anti-clogging token (ACT) is aimed at protecting the com- ``cookie'' or 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. An exchange prior to CPU-intensive public key determine its authenticity. An exchange prior to CPU-intensive public key
operations can thwart some denial of service attempts (e.g. simple flood- operations can thwart some denial of service attempts (e.g. simple flood-
ing with bogus IP source addresses). Absolute protection against denial ing with bogus IP source addresses). Absolute protection against denial
of service is impossible, but this anti-clogging token provides a tech- of service is impossible, but this anti-clogging token provides a tech-
nique for making it easier to handle. The use of an anti-clogging token nique for making it easier to handle. The use of an anti-clogging token
was introduced by Karn and Simpson in [Karn]. was introduced by Karn and Simpson in [Karn].
It should be noted that in the exchanges shown in section 4, the anti-
clogging mechanism should be used in conjuction with a garbage-state col-
lection mechanism; an attacker can still flood a server using packets with
bogus IP addresses and cause state to be created. Such aggressive memory
management techniques SHOULD be employed by protocols using ISAKMP that
do not go through an initial, anti-clogging only phase, as was done in
[Karn].
1.7.2 Connection Hijacking 1.7.2 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 prevents an exchange and security association exchanges. This linking prevents an
attacker from allowing the authentication to complete and then jumping attacker from allowing the authentication to complete and then jumping
in and impersonating one entity to the other during the key and security in and impersonating one entity to the other during the key and security
association exchanges. association exchanges.
1.7.3 Man-in-the-Middle Attacks 1.7.3 Man-in-the-Middle Attacks
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ticast traffic are presented in [RFC-1825]. Multicast security issues are ticast traffic are presented in [RFC-1825]. Multicast security issues are
also discussed in [RFC-1949] and [BC]. A future extension to ISAKMP will also discussed in [RFC-1949] and [BC]. A future extension to ISAKMP will
support multicast key distribution. For an introduction to the issues re- support multicast key distribution. For an introduction to the issues re-
lated to multicast security, consult the Internet Drafts, [RFC-2094] and lated to multicast security, consult the Internet Drafts, [RFC-2094] and
[RFC-2093], describing Sparta's research in this area. [RFC-2093], describing Sparta's research in this area.
2 Terminology and Concepts 2 Terminology and Concepts
2.1 ISAKMP Terminology 2.1 ISAKMP Terminology
Security Protocol A Security Protocol consists of an entity at a single Security Protocol: A Security Protocol consists of an entity at a single
point in the network stack, performing a security service for network com- point in the network stack, performing a security service for network com-
munication. For example, IPSEC ESP and IPSEC AH are two different secu- munication. For example, IPSEC ESP and IPSEC AH are two different secu-
rity protocols. TLS is another example. Security Protocols may perform rity protocols. TLS is another example. Security Protocols may perform
more than one service, for example providing integrity and confidentiality more than one service, for example providing integrity and confidentiality
in one module. in one module.
Protection Suite A protection suite is a list of the security services Protection Suite: A protection suite is a list of the security services
that must be applied by various security protocols. For example, a pro- that must be applied by various security protocols. For example, a pro-
tection suite may consist of DES encryption in IP ESP, and keyed MD5 in IP 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. AH. All of the protections in a suite must be treated as a single unit.
This is necessary because security services in different security pro- This is necessary because security services in different security pro-
tocols can have subtle interactions, and the effects of a suite must be tocols can have subtle interactions, and the effects of a suite must be
analyzed and verified as a whole. analyzed and verified as a whole.
Security Association (SA) A Security Association is a security-protocol- Security Association (SA): A Security Association is a security-protocol-
specific set of parameters that completely defines the services and mech- specific set of parameters that completely defines the services and mech-
anisms necessary to protect traffic at that security protocol location. anisms necessary to protect traffic at that security protocol location.
These parameters can include algorithm identifiers, modes, cryptographic These parameters can include algorithm identifiers, modes, cryptographic
keys, etc. The SA is referred to by its associated security protocol (for keys, etc. The SA is referred to by its associated security protocol (for
example, ``ISAKMP SA'', ``ESP SA'', ``TLS SA''). example, ``ISAKMP SA'', ``ESP SA'', ``TLS SA'').
ISAKMP SA An SA used by the ISAKMP servers to protect their own traffic. ISAKMP SA: An SA used by the ISAKMP servers to protect their own traffic.
Sections 2.3 and 2.4 provide more details about ISAKMP SAs. Sections 2.3 and 2.4 provide more details about ISAKMP SAs.
Security Parameter Index (SPI) An identifier for a Security Assocation, Security Parameter Index (SPI): An identifier for a Security Assocation,
relative to some security protocol. Each security protocol has its own relative to some security protocol. Each security protocol has its own
``SPI-space''. A (security protocol, SPI) pair may uniquely identify an ``SPI-space''. A (security protocol, SPI) pair may uniquely identify an
SA. The uniqueness of the SPI is implementation dependent, but could be SA. The uniqueness of the SPI is implementation dependent, but could be
based per system, per protocol, or other options. Depending on the DOI, based per system, per protocol, or other options. Depending on the DOI,
additional information (e.g. host address) may be necessary to identify additional information (e.g. host address) may be necessary to identify
an SA. The DOI will also determine which SPIs (i.e. initiator's or re- an SA. The DOI will also determine which SPIs (i.e. initiator's or re-
sponder's) are sent during communication. sponder's) are sent during communication.
Domain of Interpretation A Domain of Interpretation (DOI) defines payload Domain of Interpretation: A Domain of Interpretation (DOI) defines payload
formats, exchange types, and conventions for naming security-relevant in- formats, exchange types, and conventions for naming security-relevant in-
formation such as security policies or cryptographic algorithms and modes. formation such as security policies or cryptographic algorithms and modes.
A Domain of Interpretation (DOI) identifier is used to interpret the pay- A Domain of Interpretation (DOI) identifier is used to interpret the pay-
loads of ISAKMP payloads. A system SHOULD support multiple Domains of In- loads of ISAKMP payloads. A system SHOULD support multiple Domains of In-
terpretation simultaneously. The concept of a DOI is based on previous terpretation simultaneously. The concept of a DOI is based on previous
work by the TSIG CIPSO Working Group, but extends beyond security label work by the TSIG CIPSO Working Group, but extends beyond security label
interpretation to include naming and interpretation of security services. interpretation to include naming and interpretation of security services.
A DOI defines: A DOI defines:
o A ``situation'': the set of information that will be used to o A ``situation'': the set of information that will be used to
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attributes, and certificate authorities. attributes, and certificate authorities.
o The specific formats of the various payload contents. o The specific formats of the various payload contents.
o Additional exchange types, if required. o Additional exchange types, if required.
The rules for the IETF IP Security DOI are presented in [IPDOI]. Speci- The rules for the IETF IP Security DOI are presented in [IPDOI]. Speci-
fications of the rules for customized DOIs will be presented in separate fications of the rules for customized DOIs will be presented in separate
documents. documents.
Situation A situation contains all of the security-relevant information Situation: A situation contains all of the security-relevant information
that a system considers necessary to decide the security services required that a system considers necessary to decide the security services required
to protect the session being negotiated. The situation may include ad- to protect the session being negotiated. The situation may include ad-
dresses, security classifications, modes of operation (normal vs. emer- dresses, security classifications, modes of operation (normal vs. emer-
gency), etc. gency), etc.
Proposal A proposal is a list, in decreasing order of preference, of the Proposal: A proposal is a list, in decreasing order of preference, of the
protection suites that a system considers acceptable to protect traffic protection suites that a system considers acceptable to protect traffic
under a given situation. under a given situation.
Payload ISAKMP defines several types of payloads, which are used to trans- Payload: ISAKMP defines several types of payloads, which are used to
fer information such as security association data, or key exchange data, transfer information such as security association data, or key exchange
in DOI-defined formats. A payload consists of a generic payload header data, in DOI-defined formats. A payload consists of a generic payload
and a string of octects that is opaque to ISAKMP. ISAKMP uses DOI-specific header and a string of octects that is opaque to ISAKMP. ISAKMP uses DOI-
functionality to synthesize and interpret these payloads. Multiple pay- specific functionality to synthesize and interpret these payloads. Mul-
loads can be sent in a single ISAKMP message. See section 3 for more de- tiple payloads can be sent in a single ISAKMP message. See section 3 for
tails on the payload types, and [IPDOI] for the formats of the IETF IP Se- more details on the payload types, and [IPDOI] for the formats of the IETF
curity DOI payloads. IP Security DOI payloads.
Exchange Type An exchange type is a specification of the number of mes- Exchange Type: An exchange type is a specification of the number of mes-
sages in an ISAKMP exchange, and the payload types that are contained in sages in an ISAKMP exchange, and the payload types that are contained in
each of those messages. Each exchange type is designed to provide a par- each of those messages. Each exchange type is designed to provide a par-
ticular set of security services, such as anonymity of the participants, ticular set of security services, such as anonymity of the participants,
perfect forward secrecy of the keying material, authentication of the par- perfect forward secrecy of the keying material, authentication of the par-
ticipants, etc. Section 4.3 defines the default set of ISAKMP exchange ticipants, etc. Section 4.1 defines the default set of ISAKMP exchange
types. Other exchange types can be added to support additional key ex- types. Other exchange types can be added to support additional key ex-
changes, if required. changes, if required.
2.2 ISAKMP Placement 2.2 ISAKMP Placement
Figure 1 is a high level view of the placement of ISAKMP within a system Figure 1 is a high level view of the placement of ISAKMP within a system
context in a network architecture. An important part of negotiating secu- context in a network architecture. An important part of negotiating secu-
rity services is to consider the entire ``stack'' of individual SAs as a rity services is to consider the entire ``stack'' of individual SAs as a
unit. This is referred to as a ``protection suite''. unit. This is referred to as a ``protection suite''.
+------------+ +--------+ +--------------+ +------------+ +--------+ +--------------+
! DOI ! ! ! ! Application ! ! DOI ! ! ! ! Application !
! Definition ! <----> ! ISAKMP ! ! Process ! ! Definition ! <----> ! ISAKMP ! ! Process !
+------------+ ! ! !--------------! +------------+ --> ! ! !--------------!
+--------+ ! Appl Protocol! +--------------+ ! +--------+ ! Appl Protocol!
^ +--------------+ ! Key Exchange ! ! ^ ^ +--------------+
! ^ ! Definition !<-- ! ! ^
! ! +--------------+ ! ! !
v v ! ! !
+---------------------------------------------+ !----------------! ! !
! Socket Layer ! v ! !
!---------------------------------------------! +-------+ v v
! Transport Protocol (TCP / UDP) ! ! API ! +---------------------------------------------+
+-------+ ! Socket Layer !
! !---------------------------------------------!
v ! Transport Protocol (TCP / UDP) !
+----------+ !---------------------------------------------! +----------+ !---------------------------------------------!
! Security ! <----> ! IP ! ! Security ! <----> ! IP !
! Protocol ! !---------------------------------------------! ! Protocol ! !---------------------------------------------!
+----------+ ! Link Layer Protocol ! +----------+ ! Link Layer Protocol !
+---------------------------------------------+ +---------------------------------------------+
Figure 1: ISAKMP Relationships Figure 1: ISAKMP Relationships
2.3 Negotiation Phases 2.3 Negotiation Phases
ISAKMP offers two ``phases'' of negotiation. In the first phase, two en- ISAKMP offers two ``phases'' of negotiation. In the first phase, two en-
tities (e.g. ISAKMP servers) agree on how to protect further negotiation tities (e.g. ISAKMP servers) agree on how to protect further negotiation
traffic between themselves, establishing an ISAKMP SA. This ISAKMP SA is traffic between themselves, establishing an ISAKMP SA. This ISAKMP SA is
then used to protect the negotiations for the Protocol SA being requested. then used to protect the negotiations for the Protocol SA being requested.
Two entities (e.g. ISAKMP servers) can negotiate (and have active) multi- Two entities (e.g. ISAKMP servers) can negotiate (and have active) multi-
ple ISAKMP SAs. ple ISAKMP SAs.
The second phase of negotiation is used to establish security associa- The second phase of negotiation is used to establish security associations
tions for other security protocols. This second phase can be used to pro- for other security protocols. This second phase can be used to estab-
tect many security associations. The security associations established lish many security associations. The security associations established
by ISAKMP during this phase can be used by a security protocol to protect by ISAKMP during this phase can be used by a security protocol to protect
many message/data exchanges. many message/data exchanges.
While the two-phased approach has a higher start-up cost for most simple While the two-phased approach has a higher start-up cost for most simple
scenarios, there are several reasons that it is beneficial for most cases. scenarios, there are several reasons that it is beneficial for most cases.
First, entities (e.g. ISAKMP servers) can amortize the cost of the first First, entities (e.g. ISAKMP servers) can amortize the cost of the first
phase across several second phase negotiations. This allows multiple SAs phase across several second phase negotiations. This allows multiple SAs
to be established between peers over time without having to start over for to be established between peers over time without having to start over for
each communication. each communication.
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Note that security services may be applied differently in each negotiation Note that security services may be applied differently in each negotiation
phase. For example, different parties are being authenticated during each phase. For example, different parties are being authenticated during each
of the phases of negotiation. During the first phase, the parties being of the phases of negotiation. During the first phase, the parties being
authenticated may be the ISAKMP servers/hosts, while during the second authenticated may be the ISAKMP servers/hosts, while during the second
phase, users or application level programs are being authenticated. phase, users or application level programs are being authenticated.
2.4 Identifying Security Associations 2.4 Identifying Security Associations
While bootstrapping secure channels between systems, ISAKMP cannot assume While bootstrapping secure channels between systems, ISAKMP cannot assume
the existence of security services, and must provide some protections for the existence of security services, and must provide some protections for
itself. Therefore, ISAKMP considers an ISAKMP Security Association to be itself. Therefore, ISAKMP considers an ISAKMP Security Association to
different than other types, and manages ISAKMP SAs itself, in their own be different than other types, and manages ISAKMP SAs itself, in their
name space. ISAKMP uses the two cookie fields in the ISAKMP header to own name space. ISAKMP uses the two cookie fields in the ISAKMP header
identify ISAKMP SAs. The Message ID and SPI fields in the ISAKMP Header to identify ISAKMP SAs. The Message ID in the ISAKMP Header and the SPI
are used during SA establishment to identify the SA for other security field in the Proposal payload are used during SA establishment to identify
protocols. The interpretation of these four fields is dependent on the the SA for other security protocols. The interpretation of these four
operation taking place. fields is dependent on the operation taking place.
The following table shows the presence or absence of the cookies in the The following table shows the presence or absence of several fields during
ISAKMP header, the ISAKMP Header Message ID field, and the SPI field in SA establishment. The following fields are necessary for various opera-
the Proposal payload for various operations. An 'X' in the column means tions associated with SA establishment: cookies in the ISAKMP header, the
the value MUST be present. An 'NA' in the column means a value in the ISAKMP Header Message ID field, and the SPI field in the Proposal payload.
column is Not Applicable to the operation. An 'X' in the column means the value MUST be present. An 'NA' in the col-
umn means a value in the column is Not Applicable to the operation.
__#_____________Operation____________I-Cookie__R-Cookie__Message_ID__SPI_ __#_____________Operation____________I-Cookie__R-Cookie__Message_ID__SPI_
(1) Start ISAKMP SA negotiation X 0 0 0 (1) Start ISAKMP SA negotiation X 0 0 0
(2) Respond ISAKMP SA negotiation X X 0 0 (2) Respond ISAKMP SA negotiation X X 0 0
(3) Init other SA negotiation X X X X (3) Init other SA negotiation X X X X
(4) Respond other SA negotiation X X X X (4) Respond other SA negotiation X X X X
(5) Other (KE, ID, etc.) X X X/0 NA (5) Other (KE, ID, etc.) X X X/0 NA
(6) Security Protocol (ESP, AH) NA NA NA X (6) Security Protocol (ESP, AH) NA NA NA X
In the first line (1) of the table, the initiator includes the Initiator In the first line (1) of the table, the initiator includes the Initiator
skipping to change at page 23, line 14 skipping to change at page 22, line 35
3.1 ISAKMP Header Format 3.1 ISAKMP Header Format
An ISAKMP message has a fixed header format, shown in Figure 2, followed An ISAKMP message has a fixed header format, shown in Figure 2, followed
by a variable number of payloads. A fixed header simplifies parsing, pro- by a variable number of payloads. A fixed header simplifies parsing, pro-
viding the benefit of protocol parsing software that is less complex and viding the benefit of protocol parsing software that is less complex and
easier to implement. The fixed header contains the information required easier to implement. The fixed header contains the information required
by the protocol to maintain state, process payloads and possibly prevent by the protocol to maintain state, process payloads and possibly prevent
denial of service or replay attacks. denial of service or replay attacks.
The ISAKMP Header fields are defined as follows:
o Initiator Cookie (8 octets) - Cookie of entity that initiated SA
establishment, SA notification, or SA deletion.
o Responder Cookie (8 octets) - Cookie of entity that is responding to
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Initiator ! ! Initiator !
! Cookie ! ! Cookie !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Responder ! ! Responder !
! Cookie ! ! Cookie !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! MjVer ! MnVer ! Exchange Type ! Flags ! ! Next Payload ! MjVer ! MnVer ! Exchange Type ! Flags !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Message ID ! ! Message ID !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Length ! ! Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: ISAKMP Header Format Figure 2: ISAKMP Header Format
The ISAKMP Header fields are defined as follows:
o Initiator Cookie (8 octets) - Cookie of entity that initiated SA
establishment, SA notification, or SA deletion.
o Responder Cookie (8 octets) - Cookie of entity that is responding to
an SA establishment request, SA notification, or SA deletion. an SA establishment request, SA notification, or SA deletion.
o Next Payload (1 octet) - Indicates the type of the first payload in o Next Payload (1 octet) - Indicates the type of the first payload in
the message. The format for each payload is defined in sections 3.4 the message. The format for each payload is defined in sections 3.4
through 3.15. The processing for the payloads is defined in section through 3.16. The processing for the payloads is defined in section
5. 5.
_____Next_Payload_Type_______Value____ _____Next_Payload_Type_______Value____
NONE 0 NONE 0
Security Association (SA) 1 Security Association (SA) 1
Proposal (P) 2 Proposal (P) 2
Transform (T) 3 Transform (T) 3
Key Exchange (KE) 4 Key Exchange (KE) 4
Identification (ID) 5 Identification (ID) 5
Certificate (CERT) 6 Certificate (CERT) 6
Certificate Request (CR) 7 Certificate Request (CR) 7
Hash (HASH) 8 Hash (HASH) 8
Signature (SIG) 9 Signature (SIG) 9
Nonce (NONCE) 10 Nonce (NONCE) 10
Notification (N) 11 Notification (N) 11
Delete (D) 12 Delete (D) 12
RESERVED 13- 127 Vendor ID (VID) 13
RESERVED 14 - 127
Private USE 128 - 255 Private USE 128 - 255
o Major Version (4 bits) - indicates the major version of the ISAKMP o Major Version (4 bits) - indicates the major version of the ISAKMP
protocol in use. Implementations based on this version of the ISAKMP protocol in use. Implementations based on this version of the ISAKMP
Internet-Draft MUST set the Major Version to 1. Implementations Internet-Draft MUST set the Major Version to 1. Implementations
based on previous versions of ISAKMP Internet-Drafts MUST set the based on previous versions of ISAKMP Internet-Drafts MUST set the
Major Version to 0. Implementations SHOULD never accept packets with Major Version to 0. Implementations SHOULD never accept packets with
a major version number larger than its own. a major version number larger than its own.
o Minor Version (4 bits) - indicates the minor version of the ISAKMP o Minor Version (4 bits) - indicates the minor version of the ISAKMP
skipping to change at page 25, line 19 skipping to change at page 24, line 34
Authentication Only 3 Authentication Only 3
Aggressive 4 Aggressive 4
Informational 5 Informational 5
ISAKMP Future Use 6 - 31 ISAKMP Future Use 6 - 31
DOI Specific Use 32 - 255 DOI Specific Use 32 - 255
o Flags (1 octet) - indicates specific options that are set for the o Flags (1 octet) - indicates specific options that are set for the
ISAKMP exchange. The flags listed below are specified in the Flags ISAKMP exchange. The flags listed below are specified in the Flags
field beginning with the least significant bit, i.e the Encryption field beginning with the least significant bit, i.e the Encryption
bit is bit 0 of the Flags field, the Commit bit is bit 1 of the Flags bit is bit 0 of the Flags field, the Commit bit is bit 1 of the Flags
field, etc. field, and the Authentication Only bit is bit 2 of the Flags field.
The remaining bits of the Flags field MUST be set to 0 prior to
transmission.
-- E(ncryption Bit) (1 bit) - If set (1), all payloads following the -- E(ncryption Bit) (1 bit) - If set (1), all payloads following the
header are encrypted using the encryption algorithm identified in header are encrypted using the encryption algorithm identified in
the ISAKMP SA. The ISAKMP SA Identifier is the combination of the the ISAKMP SA. The ISAKMP SA Identifier is the combination of the
initiator and responder cookie. It is RECOMMENDED that initiator and responder cookie. It is RECOMMENDED that
encryption of communications be done as soon as possible between encryption of communications be done as soon as possible between
the peers. For all ISAKMP exchanges described in section 4.3, the peers. For all ISAKMP exchanges described in section 4.1,
the encryption SHOULD begin after both parties have exchanged Key the encryption SHOULD begin after both parties have exchanged Key
Exchange payloads. If the E(ncryption Bit) is not set (0), the Exchange payloads. If the E(ncryption Bit) is not set (0), the
payloads are not encrypted. payloads are not encrypted.
-- C(ommit Bit) (1 bit) - This bit is used to signal key exchange -- C(ommit Bit) (1 bit) - This bit is used to signal key exchange
synchronization. It is used to ensure that encrypted material is synchronization. It is used to ensure that encrypted material is
not received prior to completion of the SA establishment. The not received prior to completion of the SA establishment. The
Commit Bit can be set (at anytime) by either party participating Commit Bit can be set (at anytime) by either party participating
in the SA establishment, and can be used during both phases of an in the SA establishment, and can be used during both phases of an
ISAKMP SA establishment. However, the value MUST be reset after ISAKMP SA establishment. However, the value MUST be reset after
skipping to change at page 26, line 11 skipping to change at page 25, line 31
following a Phase 2 exchange. Handling of this situation is not following a Phase 2 exchange. Handling of this situation is not
standardized, but we propose the following possibilities. If the standardized, but we propose the following possibilities. If the
entity awaiting the Informational Exchange can verify the re- entity awaiting the Informational Exchange can verify the re-
ceived message (i.e. Phase 2 SA negotiation message or encrypted ceived message (i.e. Phase 2 SA negotiation message or encrypted
traffic), then they MAY consider the SA was established and traffic), then they MAY consider the SA was established and
continue processing. The other option is to retransmit the last continue processing. The other option is to retransmit the last
ISAKMP message to force the other entity to retransmit the final mes- ISAKMP message to force the other entity to retransmit the final mes-
sage. This suggests that implementations may consider retaining the sage. This suggests that implementations may consider retaining the
last message (locally) until they are sure the SA is established. last message (locally) until they are sure the SA is established.
-- A(uthentication Only Bit) (1 bit) - This bit is intended for use
with the Informational Exchange with a Notify payload and will
allow the transmission of information with integrity checking,
but no encryption (e.g. "emergency mode"). Section 4.8 states
that a Phase 2 Informational Exchange MUST be sent under the
protection of an ISAKMP SA. This is the only exception to that
policy. If the Authentication Only bit is set (1), only
authentication security services will be applied to the entire
Notify payload of the Informational Exchange and the payload will
not be encrypted.
o Message ID (4 octets) - Unique Message Identifier used to identify o Message ID (4 octets) - Unique Message Identifier used to identify
protocol state during Phase 2 negotiations. This value is randomly protocol state during Phase 2 negotiations. This value is randomly
generated by the initiator of the Phase 2 negotiation. During Phase generated by the initiator of the Phase 2 negotiation. In the event
1 negotiations, the value MUST be set to 0. of simultaneous SA establishments (i.e. collisions), the value of
this field will likely be different because they are independently
generated and, thus, two security associations will progress toward
establishment. However, it is unlikely there will be absolute
simultaneous establishments. During Phase 1 negotiations, the value
MUST be set to 0.
o Length (4 octets) - Length of total message (header + payloads) in o Length (4 octets) - Length of total message (header + payloads) in
octets. Encryption can expand the size of an ISAKMP message. This octets. Encryption can expand the size of an ISAKMP message.
issue is addressed in [IPDOI] and [IO-Res].
3.2 Payload Generic Header 3.2 Generic Payload Header
Each ISAKMP payload defined in sections 3.4 through 3.15 begins with a Each ISAKMP payload defined in sections 3.4 through 3.16 begins with a
generic header, shown in Figure 3, which provides a payload "chaining" generic header, shown in Figure 3, which provides a payload "chaining"
capability and clearly defines the boundaries of a payload. capability and clearly defines the boundaries of a payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Generic Payload Header Figure 3: Generic Payload Header
skipping to change at page 27, line 11 skipping to change at page 26, line 37
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
3.3 Data Attributes 3.3 Data Attributes
There are several instances within ISAKMP where it is necessary to repre- There are several instances within ISAKMP where it is necessary to repre-
sent Data Attributes. An example of this is the Security Association (SA) sent Data Attributes. An example of this is the Security Association (SA)
Attributes contained in the Transform payload (described in section 3.6). Attributes contained in the Transform payload (described in section 3.6).
These Data Attributes are not an ISAKMP payload, but are contained within These Data Attributes are not an ISAKMP payload, but are contained within
ISAKMP payloads. The format of the Data Attributes provides the flexi- ISAKMP payloads. The format of the Data Attributes provides the flexibil-
bility for representation of many different types of information. There ity for representation of many different types of information. There can
can be multiple Data Attributes within a payload. This is done using the be multiple Data Attributes within a payload. The length of the Data At-
Attribute Format bit described below. The length of the Data Attributes tributes will either be 4 octets or defined by the Attribute Length field.
will either be 4 octets or defined by the Attribute Length field. Spe- This is done using the Attribute Format bit described below. Specific in-
cific information about the attributes for each domain will be described formation about the attributes for each domain will be described in a DOI
in a DOI document, e.g. IPSEC DOI [IPDOI]. document, e.g. IPSEC DOI [IPDOI].
The Data Attributes fields are defined as follows:
o Attribute Type (2 octets) - Unique identifier for each type of
attribute. These attributes are defined as part of the DOI-specific
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
!A! Attribute Type ! AF=0 Attribute Length ! !A! Attribute Type ! AF=0 Attribute Length !
!F! ! AF=1 Attribute Value ! !F! ! AF=1 Attribute Value !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AF=0 Attribute Value . . AF=0 Attribute Value .
. AF=1 Not Transmitted . . AF=1 Not Transmitted .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Data Attributes Figure 4: Data Attributes
The Data Attributes fields are defined as follows:
o Attribute Type (2 octets) - Unique identifier for each type of
attribute. These attributes are defined as part of the DOI-specific
information. information.
The most significant bit, or Attribute Format (AF), indicates whether The most significant bit, or Attribute Format (AF), indicates whether
the data attributes follow the Type/Length/Value (TLV) format or a the data attributes follow the Type/Length/Value (TLV) format or a
shortened Type/Value (TV) format. If the AF bit is a zero (0), then shortened Type/Value (TV) format. If the AF bit is a zero (0), then
the Data Attributes are of the Type/Length/Value (TLV) form. If the the Data Attributes are of the Type/Length/Value (TLV) form. If the
AF bit is a one (1), then the Data Attributes are of the Type/Value AF bit is a one (1), then the Data Attributes are of the Type/Value
form. form.
o Attribute Length (2 octets) - Length in octets of the Attribute o Attribute Length (2 octets) - Length in octets of the Attribute
Value. When the AF bit is a one (1), the Attribute Value is only 2 Value. When the AF bit is a one (1), the Attribute Value is only 2
octets and the Attribute Length field is not present. octets and the Attribute Length field is not present.
o Attribute Value (variable length) - Value of the attribute associated o Attribute Value (variable length) - Value of the attribute associated
with the DOI-specific Attribute Type. If the AF bit is a zero (0), with the DOI-specific Attribute Type. If the AF bit is a zero (0),
this field has a variable length defined by the Attribute Length this field has a variable length defined by the Attribute Length
field. If the Attribute Value is not aligned at a 4-byte multiple, field. If the AF bit is a one (1), the Attribute Value has a length
the field is right justified and the remaining bits MUST be prepended of 2 octets.
with 0 for 4-byte alignment. If the AF bit is a one (1), the
Attribute Value has a length of 2 octets.
3.4 Security Association Payload 3.4 Security Association Payload
The Security Association Payload is used to negotiate security attributes The Security Association Payload is used to negotiate security attributes
and to indicate the Domain of Interpretation (DOI) and Situation under and to indicate the Domain of Interpretation (DOI) and Situation under
which the negotiation is taking place. Figure 5 shows the format of the which the negotiation is taking place. Figure 5 shows the format of the
Security Association payload. Security Association payload.
The Security Association Payload fields are defined as follows:
o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0. This field MUST NOT contain the
values for the Proposal or Transform payloads as they are considered
part of the security association negotiation. For example, this
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Domain of Interpretation (DOI) ! ! Domain of Interpretation (DOI) !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Situation ~ ~ Situation ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Security Association Payload Figure 5: Security Association Payload
The Security Association Payload fields are defined as follows:
o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0. This field MUST NOT contain the
values for the Proposal or Transform payloads as they are considered
part of the security association negotiation. For example, this
field would contain the value "10" (Nonce payload) in the first field would contain the value "10" (Nonce payload) in the first
message of a Base Exchange (see Section 4.4) and the value "0" in the message of a Base Exchange (see Section 4.4) and the value "0" in the
first message of an Identity Protect Exchange (see Section 4.5). first message of an Identity Protect Exchange (see Section 4.5).
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the entire Security o Payload Length (2 octets) - Length in octets of the entire Security
Association payload, including the SA payload, all Proposal payloads, Association payload, including the SA payload, all Proposal payloads,
and all Transform payloads associated with the proposed Security and all Transform payloads associated with the proposed Security
Association. Association.
o Domain of Interpretation (4 octets) - Identifies the DOI (as o Domain of Interpretation (4 octets) - Identifies the DOI (as
described in Section 2.1) under which this negotiation is taking described in Section 2.1) under which this negotiation is taking
place. For the Internet, the DOI is one (1). Other DOI's can be place. The DOI is a 32-bit unsigned integer. A DOI value of 0
defined using the description in appendix B. during a Phase 1 exchange specifies a Generic ISAKMP SA which can be
used for any protocol during the Phase 2 exchange. The necessary SA
Attributes are defined in A.4. A DOI value of 1 is assigned to the
IPsec DOI [IPDOI]. All other DOI values are reserved to IANA for
future use. IANA will not normally assign a DOI value without
referencing some public specification, such as an Internet RFC. Other
DOI's can be defined using the description in appendix B. This field
MUST be present within the Security Association payload.
o Situation (variable length) - A DOI-specific field that identifies o Situation (variable length) - A DOI-specific field that identifies
the situation under which this negotiation is taking place. The the situation under which this negotiation is taking place. The
Situation is used to make policy decisions regarding the security Situation is used to make policy decisions regarding the security
attributes being negotiated. Specifics for the IETF IP Security DOI attributes being negotiated. Specifics for the IETF IP Security DOI
Situation are detailed in [IPDOI]. Situation are detailed in [IPDOI]. This field MUST be present within
the Security Association payload.
The payload type for the Security Association Payload is one (1). The payload type for the Security Association Payload is one (1).
3.5 Proposal Payload 3.5 Proposal Payload
The Proposal Payload contains information used during Security Associa- The Proposal Payload contains information used during Security Associa-
tion negotiation. The proposal consists of security mechanisms, or trans- tion negotiation. The proposal consists of security mechanisms, or trans-
forms, to be used to secure the communications channel. Figure 6 shows forms, to be used to secure the communications channel. Figure 6 shows
the format of the Proposal Payload. A description of its use can be found the format of the Proposal Payload. A description of its use can be found
in section 4.1. in section 4.2.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Proposal # ! Protocol-Id ! SPI Size !# of Transforms! ! Proposal # ! Protocol-Id ! SPI Size !# of Transforms!
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! SPI (variable) ! ! SPI (variable) !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 29, line 46 skipping to change at page 29, line 37
o Next Payload (1 octet) - Identifier for the payload type of the next o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. This field MUST only contain the value "2" payload in the message. This field MUST only contain the value "2"
or "0". If there are additional Proposal payloads in the message, or "0". If there are additional Proposal payloads in the message,
then this field will be 2. If the current Proposal payload is the then this field will be 2. If the current Proposal payload is the
last within the security association proposal, then this field will last within the security association proposal, then this field will
be 0. be 0.
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the entire Proposal o Payload Length (2 octets) - Length in octets of the entire Proposal
payload, including the Proposal payload, and all Transform payloads payload, including generic payload header, the Proposal payload, and
associated with this proposal. In the event there are multiple all Transform payloads associated with this proposal. In the event
proposals with the same proposal number (see section 4.1), the there are multiple proposals with the same proposal number (see
Payload Length field only applies to the current Proposal payload and section 4.2), the Payload Length field only applies to the current
not to all Proposal payloads. Proposal payload and not to all Proposal payloads.
o Proposal # (1 octet) - Identifies the Proposal number for the current o Proposal # (1 octet) - Identifies the Proposal number for the current
payload. A description of the use of this field is found in section payload. A description of the use of this field is found in section
4.1. 4.2.
o Protocol-Id (1 octet) - Specifies the protocol identifier for the o Protocol-Id (1 octet) - Specifies the protocol identifier for the
current negotiation. Examples might include IPSEC ESP, IPSEC AH, current negotiation. Examples might include IPSEC ESP, IPSEC AH,
OSPF, TLS, etc. OSPF, TLS, etc.
o SPI Size (1 octet) - Length in octets of the SPI as defined by the o SPI Size (1 octet) - Length in octets of the SPI as defined by the
Protocol-Id. Protocol-Id. In the case of ISAKMP, the Initiator and Responder
cookie pair from the ISAKMP Header is the ISAKMP SPI, therefore, the
SPI Size is irrelevant and MAY be from zero (0) to sixteen (16). If
the SPI Size is non-zero, the content of the SPI field MUST be
ignored. If the SPI Size is not a multiple of 4 octets it will have
some impact on the SPI field and the alignment of all payloads in the
message. The Domain of Interpretation (DOI) will dictate the SPI
Size for other protocols.
o # of Transforms (1 octet) - Specifies the number of transforms for o # of Transforms (1 octet) - Specifies the number of transforms for
the Proposal. Each of these is contained in a Transform payload. the Proposal. Each of these is contained in a Transform payload.
o SPI (variable) - The sending entity's SPI. o SPI (variable) - The sending entity's SPI. In the event the SPI Size
is not a multiple of 4 octets, there is no padding applied to the
payload, however, it can be applied at the end of the message.
The payload type for the Proposal Payload is two (2). The payload type for the Proposal Payload is two (2).
3.6 Transform Payload 3.6 Transform Payload
The Transform Payload contains information used during Security Associa- The Transform Payload contains information used during Security Associa-
tion negotiation. The Transform payload consists of security mechanisms, tion negotiation. The Transform payload consists of a specific security
or transforms, to be used to secure the communications channel. The mechanism, or transforms, to be used to secure the communications chan-
Transform payload also contains the security association attributes asso- nel. The Transform payload also contains the security association at-
ciated with the specific transform. These SA attributes are DOI-specific. tributes associated with the specific transform. These SA attributes are
Figure 7 shows the format of the Transform Payload. A description of its DOI-specific. Figure 7 shows the format of the Transform Payload. A de-
use can be found in section 4.1. scription of its use can be found in section 4.2.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Transform # ! Transform-Id ! RESERVED2 ! ! Transform # ! Transform-Id ! RESERVED2 !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ SA Attributes ~ ~ SA Attributes ~
skipping to change at page 31, line 21 skipping to change at page 31, line 19
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header, Transform values, and all SA including the generic payload header, Transform values, and all SA
Attributes. Attributes.
o Transform # (1 octet) - Identifies the Transform number for the o Transform # (1 octet) - Identifies the Transform number for the
current payload. If there is more than one transform proposed for a current payload. If there is more than one transform proposed for a
specific protocol within the Proposal payload, then each Transform specific protocol within the Proposal payload, then each Transform
payload has a unique Transform number. A description of the use of payload has a unique Transform number. A description of the use of
this field is found in section 4.1. this field is found in section 4.2.
o Transform-Id (1 octet) - Specifies the Transform identifier for the o Transform-Id (1 octet) - Specifies the Transform identifier for the
protocol within the current proposal. These transforms are defined protocol within the current proposal. These transforms are defined
by the DOI and are dependent on the protocol being negotiated. by the DOI and are dependent on the protocol being negotiated.
o RESERVED2 (2 octets) - Unused, set to 0. o RESERVED2 (2 octets) - Unused, set to 0.
o SA Attributes (variable length) - This field contains the security o SA Attributes (variable length) - This field contains the security
association attributes as defined for the transform given in the association attributes as defined for the transform given in the
Transform-Id field. The SA Attributes SHOULD be represented using Transform-Id field. The SA Attributes SHOULD be represented using
the Data Attributes format described in section 3.3. the Data Attributes format described in section 3.3. If the SA
Attributes are not aligned on 4-byte boundaries, then subsequent
payloads will not be aligned and any padding will be added at the end
of the message to make the message 4-octet aligned.
The payload type for the Transform Payload is three (3). The payload type for the Transform Payload is three (3).
3.7 Key Exchange Payload 3.7 Key Exchange Payload
The Key Exchange Payload supports a variety of key exchange techniques. The Key Exchange Payload supports a variety of key exchange techniques.
Example key exchanges are Oakley [Oakley], Diffie-Hellman, the enhanced Example key exchanges are Oakley [Oakley], Diffie-Hellman, the enhanced
Diffie-Hellman key exchange described in X9.42 [ANSI], and the RSA-based Diffie-Hellman key exchange described in X9.42 [ANSI], and the RSA-based
key exchange used by PGP. Figure 8 shows the format of the Key Exchange key exchange used by PGP. Figure 8 shows the format of the Key Exchange
payload. payload.
The Key Exchange Payload fields are defined as follows: The Key Exchange Payload fields are defined as follows:
o Next Payload (1 octet) - Identifier for the payload type of the next o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the payload in the message. If the current payload is the last in the
message, then this field will be 0. message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Key Exchange Data ~ ~ Key Exchange Data ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Key Exchange Payload Format Figure 8: Key Exchange Payload Format
o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
o Key Exchange Data (variable length) - Data required to generate a o Key Exchange Data (variable length) - Data required to generate a
session key. The interpretation of this data is specified by the DOI session key. The interpretation of this data is specified by the DOI
and the associated Key Exchange algorithm. This field may also and the associated Key Exchange algorithm. This field may also
contain pre-placed key indicators. contain pre-placed key indicators.
The payload type for the Key Exchange Payload is four (4). The payload type for the Key Exchange Payload is four (4).
skipping to change at page 32, line 47 skipping to change at page 33, line 4
o Next Payload (1 octet) - Identifier for the payload type of the next o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the payload in the message. If the current payload is the last in the
message, then this field will be 0. message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
o ID Type (1 octet) - Specifies the type of Identification being used. o ID Type (1 octet) - Specifies the type of Identification being used.
This field is DOI-dependent.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ID Type ! RESERVED2 ! ! ID Type ! DOI Specific ID Data !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Identification Data ~ ~ Identification Data ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Identification Payload Format Figure 9: Identification Payload Format
o RESERVED2 (3 octets) - Unused, set to 0. This field is DOI-dependent.
o DOI Specific ID Data (3 octets) - Contains DOI specific
Identification data. If unused, then this field MUST be set to 0.
o Identification Data (variable length) - Contains identity o Identification Data (variable length) - Contains identity
information. The values for this field are DOI-specific and the information. The values for this field are DOI-specific and the
format is specified by the ID Type field. Specific details for the format is specified by the ID Type field. Specific details for the
IETF IP Security DOI Identification Data are detailed in [IPDOI]. IETF IP Security DOI Identification Data are detailed in [IPDOI].
The payload type for the Identification Payload is five (5). The payload type for the Identification Payload is five (5).
3.9 Certificate Payload 3.9 Certificate Payload
skipping to change at page 33, line 46 skipping to change at page 34, line 4
the Certificate Payload. the Certificate Payload.
NOTE: Certificate types and formats are not generally bound to a DOI - it NOTE: Certificate types and formats are not generally bound to a DOI - it
is expected that there will only be a few certificate types, and that most is expected that there will only be a few certificate types, and that most
DOIs will accept all of these types. DOIs will accept all of these types.
The Certificate Payload fields are defined as follows: The Certificate Payload fields are defined as follows:
o Next Payload (1 octet) - Identifier for the payload type of the next o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the payload in the message. If the current payload is the last in the
message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Cert Encoding ! ! ! Cert Encoding ! !
+-+-+-+-+-+-+-+-+ ! +-+-+-+-+-+-+-+-+ !
~ Certificate Data ~ ~ Certificate Data ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Certificate Payload Format Figure 10: Certificate Payload Format
message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
o Certificate Encoding (1 octet) - This field indicates the type of o Certificate Encoding (1 octet) - This field indicates the type of
certificate or certificate-related information contained in the certificate or certificate-related information contained in the
Certificate Data field. Certificate Data field.
__________Certificate_Type___________Value___ _________Certificate_Type____________Value____
NONE 0 NONE 0
PKCS #7 wrapped X.509 certificate 1 PKCS #7 wrapped X.509 certificate 1
PGP Certificate 2 PGP Certificate 2
DNS Signed Key 3 DNS Signed Key 3
X.509 Certificate - Signature 4 X.509 Certificate - Signature 4
X.509 Certificate - Key Exchange 5 X.509 Certificate - Key Exchange 5
Kerberos Tokens 6 Kerberos Tokens 6
Certificate Revocation List (CRL) 7 Certificate Revocation List (CRL) 7
Authority Revocation List (ARL) 8 Authority Revocation List (ARL) 8
SPKI Certificate 9 SPKI Certificate 9
RESERVED 10- 255 X.509 Certificate - Attribute 10
RESERVED 11 - 255
o Certificate Data (variable length) - Actual encoding of certificate o Certificate Data (variable length) - Actual encoding of certificate
data. The type of certificate is indicated by the Certificate data. The type of certificate is indicated by the Certificate
Encoding field. Encoding field.
The payload type for the Certificate Payload is six (6). The payload type for the Certificate Payload is six (6).
3.10 Certificate Request Payload 3.10 Certificate Request Payload
The Certificate Request Payload provides a means to request certificates The Certificate Request Payload provides a means to request certificates
via ISAKMP and can appear in any message. Certificate Request payloads via ISAKMP and can appear in any message. Certificate Request payloads
SHOULD be included in an exchange whenever an appropriate directory ser- SHOULD be included in an exchange whenever an appropriate directory ser-
vice (e.g. Secure DNS [DNSSEC]) is not available to distribute certifi- vice (e.g. Secure DNS [DNSSEC]) is not available to distribute certifi-
cates. The Certificate Request payloads MUST be accepted at any point cates. The Certificate Request payload MUST be accepted at any point dur-
during the exchange. The responder to the Certificate Request payload ing the exchange. The responder to the Certificate Request payload MUST
MUST send its immediate certificate, if certificates are supported, and send its certificate, if certificates are supported, based on the values
SHOULD send as much of its certificate chain as possible. Figure 11 shows contained in the payload. If multiple certificates are required, then
the format of the Certificate Request Payload. multiple Certificate Request payloads SHOULD be transmitted. Figure 11
shows the format of the Certificate Request Payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! # Cert. Types ! ! ! Cert. Type ! !
+-+-+-+-+-+-+-+-+ !
~ Certificate Types ~
! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! # Cert. Auths ! !
+-+-+-+-+-+-+-+-+ ! +-+-+-+-+-+-+-+-+ !
~ Certificate Authorities ~ ~ Certificate Authority ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Certificate Request Payload Format Figure 11: Certificate Request Payload Format
The Certificate Payload fields are defined as follows: The Certificate Payload fields are defined as follows:
o Next Payload (1 octet) - Identifier for the payload type of the next o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the payload in the message. If the current payload is the last in the
message, then this field will be 0. message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
o # Certificate Types (1 octet) - The number of Certificate Types o Certificate Type (1 octet) - Contains an encoding of the type of
contained in the Certificate Types field. certificate requested. Acceptable values are listed in section 3.9.
o Certificate Types (variable length) - Contains a list of the types of
certificates requested, sorted in order of preference. Each
individual certificate type is 1 octet. This field is NOT required
to end on a 4-octet boundary. It is shown as ending on a 4-octet
boundary in Figure 11 for drawing purposes only.
o # Certificate Authorities (1 octet) - The number of Certificate Au-
thorities contained in the Certificate Authorities field. This field
is NOT required to begin on a 4-octet boundary. It is shown as be-
ginning on a 4-octet boundary in Figure 11 for drawing purposes only.
o Certificate Authorities (variable length) - Contains a list of Data o Certificate Authority (variable length) - Contains an encoding of an
Attributes (see section 3.3) which indicate the Distinguished Names acceptable certificate authority for the type of certificate
of acceptable certificate authorities. See [IPDOI] for the requested. As an example, for an X.509 certificate this field would
Distinguished Name Attribute Type value. contain the Distinguished Name encoding of the Issuer Name of an
X.509 certificate authority acceptable to the sender of this payload.
This would be included to assist the responder in determining how
much of the certificate chain would need to be sent in response to
this request. If there is no specific certificate authority
requested, this field SHOULD not be included.
The payload type for the Certificate Request Payload is seven (7). The payload type for the Certificate Request Payload is seven (7).
3.11 Hash Payload 3.11 Hash Payload
The Hash Payload contains data generated by the hash function (selected The Hash Payload contains data generated by the hash function (selected
during the SA establishment exchange), over some part of the message during the SA establishment exchange), over some part of the message
and/or ISAKMP state. This payload may be used to verify the integrity of and/or ISAKMP state. This payload may be used to verify the integrity of
the data in an ISAKMP message or for authentication of the negotiating en- the data in an ISAKMP message or for authentication of the negotiating en-
tities. Figure 12 shows the format of the Hash Payload. tities. Figure 12 shows the format of the Hash Payload.
skipping to change at page 38, line 10 skipping to change at page 37, line 47
o Signature Data (variable length) - Data that results from applying o Signature Data (variable length) - Data that results from applying
the digital signature function to the ISAKMP message and/or state. the digital signature function to the ISAKMP message and/or state.
The payload type for the Signature Payload is nine (9). The payload type for the Signature Payload is nine (9).
3.13 Nonce Payload 3.13 Nonce Payload
The Nonce Payload contains random data used to guarantee liveness dur- The Nonce Payload contains random data used to guarantee liveness dur-
ing an exchange and protect against replay attacks. Figure 14 shows the ing an exchange and protect against replay attacks. Figure 14 shows the
format of the Nonce Payload. If nonces are used by a particular key ex- format of the Nonce Payload. If nonces are used by a particular key ex-
change, the use of the Nonce payload would be dictated by the key ex- change, the use of the Nonce payload will be dictated by the key exchange.
change. The nonces may be transmitted as part of the key exchange data, The nonces may be transmitted as part of the key exchange data, or as a
or as a separate payload. However, this is defined by the key exchange, separate payload. However, this is defined by the key exchange, not by
not by ISAKMP. ISAKMP.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length ! ! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Nonce Data ~ ~ Nonce Data ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 40, line 4 skipping to change at page 39, line 44
payload in the message. If the current payload is the last in the payload in the message. If the current payload is the last in the
message, then this field will be 0. message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
o Domain of Interpretation (4 octets) - Identifies the DOI (as o Domain of Interpretation (4 octets) - Identifies the DOI (as
described in Section 2.1) under which this notification is taking described in Section 2.1) under which this notification is taking
place. For the Internet, the DOI is one (1). Other DOI's can be place. For ISAKMP this value is zero (0) and for the IPSEC DOI it is
defined using the description in appendix B. one (1). Other DOI's can be defined using the description in
appendix B.
o Protocol-Id (1 octet) - Specifies the protocol identifier for the o Protocol-Id (1 octet) - Specifies the protocol identifier for the
current notification. Examples might include ISAKMP, IPSEC ESP, current notification. Examples might include ISAKMP, IPSEC ESP,
IPSEC AH, OSPF, TLS, etc. IPSEC AH, OSPF, TLS, etc.
o SPI Size (1 octet) - Length in octets of the SPI as defined by the o SPI Size (1 octet) - Length in octets of the SPI as defined by the
Protocol-Id. In the case of ISAKMP, the Initiator and Responder Protocol-Id. In the case of ISAKMP, the Initiator and Responder
cookie pair is the ISAKMP SPI, therefore, the SPI Size would be 16 cookie pair from the ISAKMP Header is the ISAKMP SPI, therefore, the
octets for the SPI. SPI Size is irrelevant and MAY be from zero (0) to sixteen (16). If
the SPI Size is non-zero, the content of the SPI field MUST be
ignored. The Domain of Interpretation (DOI) will dictate the SPI
Size for other protocols.
o Notify Message Type (2 octets) - Specifies the type of notification o Notify Message Type (2 octets) - Specifies the type of notification
message (see section 3.14.1). Additional text, if specified by the message (see section 3.14.1). Additional text, if specified by the
DOI, is placed in the Notification Data field. DOI, is placed in the Notification Data field.
o SPI (variable length) - Security Parameter Index. The receiving o SPI (variable length) - Security Parameter Index. The receiving
entity's SPI. The use of the SPI field is described in section 2.4. entity's SPI. The use of the SPI field is described in section 2.4.
The length of this field is determined by the SPI Size field. The length of this field is determined by the SPI Size field and is
not necessarily aligned to a 4 octet boundary.
o Notification Data (variable length) - Informational or error data o Notification Data (variable length) - Informational or error data
transmitted in addition to the Notify Message Type. Values for this transmitted in addition to the Notify Message Type. Values for this
field are DOI-specific. field are DOI-specific.
The payload type for the Notification Payload is eleven (11). The payload type for the Notification Payload is eleven (11).
3.14.1 Notify Message Types 3.14.1 Notify Message Types
Notification information can be error messages specifying why an SA could Notification information can be error messages specifying why an SA could
skipping to change at page 41, line 28 skipping to change at page 41, line 28
INVALID-SPI 11 INVALID-SPI 11
INVALID-TRANSFORM-ID 12 INVALID-TRANSFORM-ID 12
ATTRIBUTES-NOT-SUPPORTED 13 ATTRIBUTES-NOT-SUPPORTED 13
NO-PROPOSAL-CHOSEN 14 NO-PROPOSAL-CHOSEN 14
BAD-PROPOSAL-SYNTAX 15 BAD-PROPOSAL-SYNTAX 15
PAYLOAD-MALFORMED 16 PAYLOAD-MALFORMED 16
INVALID-KEY-INFORMATION 17 INVALID-KEY-INFORMATION 17
INVALID-ID-INFORMATION 18 INVALID-ID-INFORMATION 18
INVALID-CERT-ENCODING 19 INVALID-CERT-ENCODING 19
INVALID-CERTIFICATE 20 INVALID-CERTIFICATE 20
BAD-CERT-REQUEST-SYNTAX 21 CERT-TYPE-UNSUPPORTED 21
INVALID-CERT-AUTHORITY 22 INVALID-CERT-AUTHORITY 22
INVALID-HASH-INFORMATION 23 INVALID-HASH-INFORMATION 23
AUTHENTICATION-FAILED 24 AUTHENTICATION-FAILED 24
INVALID-SIGNATURE 25 INVALID-SIGNATURE 25
ADDRESS-NOTIFICATION 26 ADDRESS-NOTIFICATION 26
RESERVED (Future Use) 27-8191 NOTIFY-SA-LIFETIME 27
CERTIFICATE-UNAVAILABLE 28
RESERVED (Future Use) 29 - 8191
Private Use 8192 - 16383 Private Use 8192 - 16383
NOTIFY MESSAGES - STATUS TYPES NOTIFY MESSAGES - STATUS TYPES
________Status_____________Value______ _________Status_____________Value______
CONNECTED 16384 CONNECTED 16384
RESERVED (Future Use) 16385- 24575 RESERVED (Future Use) 16385 - 24575
Private Use 24576 - 32767 DOI-specific codes 24576 - 32767
Private Use 32768 - 40959
RESERVED (Future Use) 40960 - 65535
3.15 Delete Payload 3.15 Delete Payload
The Delete Payload contains a protocol-specific security association iden- The Delete Payload contains a protocol-specific security association iden-
tifier that the sender has removed from its security association database tifier that the sender has removed from its security association database
and is, therefore, no longer valid. Figure 16 shows the format of the and is, therefore, no longer valid. Figure 16 shows the format of the
Delete Payload. It is possible to send multiple SPIs in a Delete payload, Delete Payload. It is possible to send multiple SPIs in a Delete payload,
however, each SPI MUST be for the same protocol. Mixing of Protocol Iden- however, each SPI MUST be for the same protocol. Mixing of Protocol Iden-
tifiers MUST NOT be performed with the Delete payload. tifiers MUST NOT be performed with the Delete payload.
Deletion which is concerned with an ISAKMP SA will contain a Protocol-Id Deletion which is concerned with an ISAKMP SA will contain a Protocol-Id
of ISAKMP and the SPIs are the initiator and responder cookies. Deletion of ISAKMP and the SPIs are the initiator and responder cookies from the
which is concerned with a Protocol SA, such as ESP or AH, will contain the ISAKMP Header. Deletion which is concerned with a Protocol SA, such as
Protocol-Id of that protocol (e.g. ESP, AH) and the SPI is the sending ESP or AH, will contain the Protocol-Id of that protocol (e.g. ESP, AH)
entity's SPI(s). and the SPI is the sending entity's SPI(s).
NOTE: The Delete Payload is not a request for the responder to delete an NOTE: The Delete Payload is not a request for the responder to delete an
SA, but an advisory from the initiator to the responder. If the responder SA, but an advisory from the initiator to the responder. If the responder
chooses to ignore the message, the next communication from the responder chooses to ignore the message, the next communication from the responder
to the initiator, using that security association, will fail. A responder to the initiator, using that security association, will fail. A responder
is not expected to acknowledge receipt of a Delete payload. is not expected to acknowledge receipt of a Delete payload.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 42, line 44 skipping to change at page 42, line 48
payload in the message. If the current payload is the last in the payload in the message. If the current payload is the last in the
message, then this field will be 0. message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0. o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload, o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header. including the generic payload header.
o Domain of Interpretation (4 octets) - Identifies the DOI (as o Domain of Interpretation (4 octets) - Identifies the DOI (as
described in Section 2.1) under which this deletion is taking place. described in Section 2.1) under which this deletion is taking place.
For the Internet, the DOI is one (1). Other DOI's can be defined For ISAKMP this value is zero (0) and for the IPSEC DOI it is one
using the description in appendix B. (1). Other DOI's can be defined using the description in appendix B.
o Protocol-Id (1 octet) - ISAKMP can establish security associations o Protocol-Id (1 octet) - ISAKMP can establish security associations
for various protocols, including ISAKMP and IPSEC. This field identi- for various protocols, including ISAKMP and IPSEC. This field identi-
fies which security association database to apply the delete request. fies which security association database to apply the delete request.
o SPI Size (1 octet) - Length in octets of the SPI as defined by the o SPI Size (1 octet) - Length in octets of the SPI as defined by the
Protocol-Id. In the case of ISAKMP, the Initiator and Responder Protocol-Id. In the case of ISAKMP, the Initiator and Responder
cookie pair is the ISAKMP SPI. In this case, the SPI Size would be 16 cookie pair is the ISAKMP SPI. In this case, the SPI Size would be 16
octets for each SPI being deleted. octets for each SPI being deleted.
o # of SPIs (2 octets) - The number of SPIs contained in the Delete o # of SPIs (2 octets) - The number of SPIs contained in the Delete
payload. The size of each SPI is defined by the SPI Size field. payload. The size of each SPI is defined by the SPI Size field.
o Security Parameter Index(es) (variable length) - Identifies the o Security Parameter Index(es) (variable length) - Identifies the
specific security association(s) to delete. Values for this field specific security association(s) to delete. Values for this field
are DOI and protocol specific. The length of this field is are DOI and protocol specific. The length of this field is
determined by the SPI Size and # of SPIs fields. determined by the SPI Size and # of SPIs fields.
The payload type for the Delete Payload is twelve (12). The payload type for the Delete Payload is twelve (12).
3.16 Vendor ID Payload
The Vendor ID Payload contains a vendor defined constant. The constant
is used by vendors to identify and recognize remote instances of their
implementations. This mechanism allows a vendor to experiment with new
features while maintaining backwards compatibility. This is not a general
extension facility of ISAKMP. Figure 17 shows the format of the Vendor ID
Payload.
The Vendor ID payload is not an announcement from the sender that it will
send private payload types. A vendor sending the Vendor ID MUST not make
any assumptions about private payloads that it may send unless a Vendor ID
is received as well. Multiple Vendor ID payloads MAY be sent. An imple-
mentation is NOT REQUIRED to understand any Vendor ID payloads. An imple-
mentation is NOT REQUIRED to send any Vendor ID payload at all. If a pri-
vate payload was sent without prior agreement to send it, a compliant im-
plementation may reject a proposal with a notify message of type INVALID-
PAYLOAD-TYPE.
If a Vendor ID payload is sent, it MUST be sent during the Phase 1 negoti-
ation. Reception of a familiar Vendor ID payload in the Phase 1 negotia-
tion allows an implementation to make use of Private USE payload numbers
(128-255), described in section 3.1 for vendor specific extensions during
Phase 2 negotiations. The definition of "familiar" is left to implementa-
tions to determine. Some vendors may wish to implement another vendor's
extension prior to standardization. However, this practice SHOULD not be
widespread and vendors should work towards standardization instead.
The vendor defined constant MUST be unique. The choice of hash and text
to hash is left to the vendor to decide. As an example, vendors could
generate their vendor id by taking a plain (non-keyed) hash of a string
containing the product name, and the version of the product. A hash is
used instead of a vendor registry to avoid local cryptographic policy
problems with having a list of "approved" products, to keep away from
maintaining a list of vendors, and to allow classified products to avoid
having to appear on any list. For instance:
"Example Company IPsec. Version 97.1"
(not including the quotes) has MD5 hash:
48544f9b1fe662af98b9b39e50c01a5a, when using MD5file. Vendors may include
all of the hash, or just a portion of it, as the payload length will bound
the data. There are no security implications of this hash, so its choice
is arbitrary.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! !
~ Vendor ID (VID) ~
! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Vendor ID Payload Format
The Vendor ID Payload fields are defined as follows:
o Next Payload (1 octet) - Identifier for the payload type of the next
payload in the message. If the current payload is the last in the
message, then this field will be 0.
o RESERVED (1 octet) - Unused, set to 0.
o Payload Length (2 octets) - Length in octets of the current payload,
including the generic payload header.
o Vendor ID (variable length) - Hash of the vendor string plus version
(as described above).
The payload type for the Vendor ID Payload is thirteen (13).
4 ISAKMP Exchanges 4 ISAKMP Exchanges
ISAKMP supplies the basic syntax of a message exchange. The basic build- ISAKMP supplies the basic syntax of a message exchange. The basic build-
ing blocks for ISAKMP messages are the payload types described in section ing blocks for ISAKMP messages are the payload types described in section
3. This section describes the procedures for SA establishment and SA mod- 3. This section describes the procedures for SA establishment and SA mod-
ification, followed by a default set of exchanges that MAY be used for ification, followed by a default set of exchanges that MAY be used for
initial interoperability. Other exchanges will be defined depending on initial interoperability. Other exchanges will be defined depending on
the DOI and key exchange. [IPDOI] and [?] are examples of how this is the DOI and key exchange. [IPDOI] and [IKE] are examples of how this is
achieved. Appendix ?? explains the procedures for accomplishing these achieved. Appendix B explains the procedures for accomplishing these ad-
additions. ditions.
4.1 Security Association Establishment 4.1 ISAKMP Exchange Types
ISAKMP allows the creation of exchanges for the establishment of Security
Associations and keying material. There are currently five default Ex-
change Types defined for ISAKMP. Sections 4.4 through 4.8 describe these
exchanges. Exchanges define the content and ordering of ISAKMP messages
during communications between peers. Most exchanges will include all the
basic payload types - SA, KE, ID, SIG - and may include others. The pri-
mary difference between exchange types is the ordering of the messages and
the payload ordering within each message. While the ordering of payloads
within messages is not mandated, for processing efficiency it is RECOM-
MENDED that the Security Association payload be the first payload within
an exchange. Processing of each payload within an exchange is described
in section 5.
Sections 4.4 through 4.8 provide a default set of ISAKMP exchanges. These
exchanges provide different security protection for the exchange itself
and information exchanged. The diagrams in each of the following sections
show the message ordering for each exchange type as well as the payloads
included in each message, and provide basic notes describing what has hap-
pened after each message exchange. None of the examples include any "op-
tional payloads", like certificate and certificate request. Additionally,
none of the examples include an initial exchange of ISAKMP Headers (con-
taining initiator and responder cookies) which would provide protection
against clogging (see section 2.5.3).
The defined exchanges are not meant to satisfy all DOI and key exchange
protocol requirements. If the defined exchanges meet the DOI require-
ments, then they can be used as outlined. If the defined exchanges do
not meet the security requirements defined by the DOI, then the DOI MUST
specify new exchange type(s) and the valid sequences of payloads that make
up a successful exchange, and how to build and interpret those payloads.
All ISAKMP implementations MUST implement the Informational Exchange and
SHOULD implement the other four exchanges. However, this is dependent on
the definition of the DOI and associated key exchange protocols.
As discussed above, these exchange types can be used in either phase of
negotiation. However, they may provide different security properties
in each of the phases. With each of these exchanges, the combination of
cookies and SPI fields identifies whether this exchange is being used in
the first or second phase of a negotiation.
4.1.1 Notation
The following notation is used to describe the ISAKMP exchange types,
shown in the next section, with the message formats and associated pay-
loads:
HDR is an ISAKMP header whose exchange type defines the payload orderings
SA is an SA negotiation payload with one or more Proposal and
Transform payloads. An initiator MAY provide multiple proposals
for negotiation; a responder MUST reply with only one.
KE is the key exchange payload.
IDx is the identity payload for "x". x can be: "ii" or "ir"
for the ISAKMP initiator and responder, respectively, or x can
be: "ui", "ur" (when the ISAKMP daemon is a proxy negotiator),
for the user initiator and responder, respectively.
HASH is the hash payload.
SIG is the signature payload. The data to sign is exchange-specific.
AUTH is a generic authentication mechanism, such as HASH or SIG.
NONCE is the nonce payload.
'*' signifies payload encryption after the ISAKMP header. This
encryption MUST begin immediately after the ISAKMP header and
all payloads following the ISAKMP header MUST be encrypted.
=> signifies "initiator to responder" communication
<= signifies "responder to initiator" communication
4.2 Security Association Establishment
The Security Association, Proposal, and Transform payloads are used to The Security Association, Proposal, and Transform payloads are used to
build ISAKMP messages for the negotiation and establishment of SAs. An build ISAKMP messages for the negotiation and establishment of SAs. An
SA establishment message consists of a single SA payload followed by at SA establishment message consists of a single SA payload followed by at
least one, and possibly many, Proposal payloads and at least one, and pos- least one, and possibly many, Proposal payloads and at least one, and pos-
sibly many, Transform payloads associated with each Proposal payload. Be- sibly many, Transform payloads associated with each Proposal payload. Be-
cause these payloads are considered together, the SA payload will point to cause these payloads are considered together, the SA payload will point to
any following payloads and not to the Proposal payload included with the any following payloads and not to the Proposal payload included with the
SA payload. The SA Payload contains the DOI and Situation for the pro- SA payload. The SA Payload contains the DOI and Situation for the pro-
posed SA. Each Proposal payload contains a Security Parameter Index (SPI) posed SA. Each Proposal payload contains a Security Parameter Index (SPI)
and ensures that the SPI is associated with the Protocol-Id in accordance and ensures that the SPI is associated with the Protocol-Id in accordance
with the Internet Security Architecture [RFC-1825]. Proposal payloads may with the Internet Security Architecture [RFC-1825]. Proposal payloads may
or may not have the same SPI, as this is implementation dependent. Each or may not have the same SPI, as this is implementation dependent. Each
Transform Payload contains the specific security mechanisms to be used for Transform Payload contains the specific security mechanisms to be used for
the designated protocol. It is expected that the Proposal and Transform the designated protocol. It is expected that the Proposal and Transform
payloads will be used only during SA establishment negotiation. The cre- payloads will be used only during SA establishment negotiation. The cre-
ation of payloads for security association negotiation and establishment ation of payloads for security association negotiation and establishment
described here in this section are applicable for all ISAKMP exchanges de- described here in this section are applicable for all ISAKMP exchanges de-
scribed later in sections 4.4 through 4.8. The examples shown in 4.1.1 scribed later in sections 4.4 through 4.8. The examples shown in 4.2.1
contain only the SA, Proposal, and Transform payloads and do not contain contain only the SA, Proposal, and Transform payloads and do not contain
other payloads that might exist for a given ISAKMP exchange. other payloads that might exist for a given ISAKMP exchange.
The Proposal payload provides the initiating entity with the capability The Proposal payload provides the initiating entity with the capability
to present to the responding entity the security protocols and associated to present to the responding entity the security protocols and associated
security mechanisms for use with the security association being negoti- security mechanisms for use with the security association being negoti-
ated. If the SA establishment negotiation is for a combined protection ated. If the SA establishment negotiation is for a combined protection
suite consisting of multiple protocols, then there MUST be multiple Pro- suite consisting of multiple protocols, then there MUST be multiple Pro-
posal payloads each with the same Proposal number. These proposals MUST posal payloads each with the same Proposal number. These proposals MUST
be considered as a unit and MUST NOT be separated by a proposal with a be considered as a unit and MUST NOT be separated by a proposal with a
skipping to change at page 45, line 11 skipping to change at page 48, line 17
payload associated with the Protocol. The responder SHOULD retain the payload associated with the Protocol. The responder SHOULD retain the
Proposal # field in the Proposal payload and the Transform # field in Proposal # field in the Proposal payload and the Transform # field in
each Transform payload of the selected Proposal. Retention of Proposal each Transform payload of the selected Proposal. Retention of Proposal
and Transform numbers should speed the initiator's protocol processing by and Transform numbers should speed the initiator's protocol processing by
negating the need to compare the respondor's selection with every offered negating the need to compare the respondor's selection with every offered
option. These values enable the initiator to perform the comparison di- option. These values enable the initiator to perform the comparison di-
rectly and quickly. The initiator MUST verify that the Security Associa- rectly and quickly. The initiator MUST verify that the Security Associa-
tion payload received from the responder matches one of the proposals sent tion payload received from the responder matches one of the proposals sent
initially. initially.
4.1.1 Security Association Establishment Examples 4.2.1 Security Association Establishment Examples
This example shows a Proposal for a combined protection suite with two This example shows a Proposal for a combined protection suite with two
different protocols. The first protocol is presented with two transforms different protocols. The first protocol is presented with two transforms
supported by the proposer. The second protocol is presented with a sin- supported by the proposer. The second protocol is presented with a sin-
gle transform. An example for this proposal might be: Protocol 1 is ESP gle transform. An example for this proposal might be: Protocol 1 is ESP
with Transform 1 as 3DES and Transform 2 as DES AND Protocol 2 is AH with with Transform 1 as 3DES and Transform 2 as DES AND Protocol 2 is AH with
Transform 1 as SHA. The responder MUST select from the two transforms pro- Transform 1 as SHA. The responder MUST select from the two transforms pro-
posed for ESP. The resulting protection suite will be either (1) 3DES AND posed for ESP. The resulting protection suite will be either (1) 3DES AND
SHA OR (2) DES AND SHA, depending on which ESP transform was selected by SHA OR (2) DES AND SHA, depending on which ESP transform was selected by
the responder. Note this example is shown using the Base Exchange. the responder. Note this example is shown using the Base Exchange.
skipping to change at page 47, line 26 skipping to change at page 50, line 32
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ ! SA Attributes ! \ ! SA Attributes !
>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ ! NP = 0 ! RESERVED ! Payload Length ! / ! NP = 0 ! RESERVED ! Payload Length !
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Tran 2 ! Transform # 2 ! Transform ID ! RESERVED2 ! Tran 2 ! Transform # 2 ! Transform ID ! RESERVED2 !
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ ! SA Attributes ! \ ! SA Attributes !
\+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2 Security Association Modification 4.3 Security Association Modification
Security Association modification within ISAKMP is accomplished by cre- Security Association modification within ISAKMP is accomplished by cre-
ating a new SA and initiating communications using that new SA. Deletion ating a new SA and initiating communications using that new SA. Deletion
of the old SA can be done anytime after the new SA is established. Dele- of the old SA can be done anytime after the new SA is established. Dele-
tion of the old SA is dependent on local security policy. Modification of tion of the old SA is dependent on local security policy. Modification of
SAs by using a "Create New SA followed by Delete Old SA" method is done to SAs by using a "Create New SA followed by Delete Old SA" method is done to
avoid potential vulnerabilities in synchronizing modification of existing avoid potential vulnerabilities in synchronizing modification of existing
SA attributes. The procedures for creating new SAs is outlined in section SA attributes. The procedure for creating new SAs is outlined in section
4.1. The procedures for deleting SAs is outlined in section 5.13. 4.2. The procedure for deleting SAs is outlined in section 5.15.
Modification of an ISAKMP SA (phase 1 negotiation) follows the same proce- Modification of an ISAKMP SA (phase 1 negotiation) follows the same proce-
dure as creation of an ISAKMP SA. There is no relationship between the two dure as creation of an ISAKMP SA. There is no relationship between the two
SAs and the initiator and responder cookie pairs SHOULD be different, as SAs and the initiator and responder cookie pairs SHOULD be different, as
outlined in section 2.5.3. outlined in section 2.5.3.
Modification of a Protocol SA (phase 2 negotiation) follows the same pro- Modification of a Protocol SA (phase 2 negotiation) follows the same pro-
cedure as creation of a Protocol SA. The creation of a new SA is protected cedure as creation of a Protocol SA. The creation of a new SA is protected
by the existing ISAKMP SA. There is no relationship between the two Proto- by the existing ISAKMP SA. There is no relationship between the two Proto-
col SAs. A protocol implementation SHOULD begin using the newly created col SAs. A protocol implementation SHOULD begin using the newly created
SA for outbound traffic and SHOULD continue to support incoming traffic on SA for outbound traffic and SHOULD continue to support incoming traffic
the old SA until it is deleted. on the old SA until it is deleted or until traffic is received under the
protection of the newly created SA. As stated previously in this section,
4.3 ISAKMP Exchange Types deletion of an old SA is then dependent on local security policy.
ISAKMP allows the creation of exchanges for the establishment of Security
Associations and keying material. There are currently five default Ex-
change Types defined for ISAKMP. Sections 4.4 through 4.8 describe these
exchanges. Exchanges define the content and ordering of ISAKMP messages
during communications between peers. Most exchanges will include all the
basic payload types - SA, KE, ID, SIG - and may include others. The pri-
mary difference between exchange types is the ordering of the messages
and the payload ordering within each message. Processing of each payload
within an exchange is described in section 5.
Sections 4.4 through 4.8 provide a default set of ISAKMP exchanges. These
exchanges provide different security protection for the exchange itself
and information exchanged. The diagrams in each of the following sections
show the message ordering for each exchange type as well as the payloads
included in each message, and provide basic notes describing what has hap-
pened after each message exchange. None of the examples include any "op-
tional payloads", like certificate and certificate request. Additionally,
none of the examples include an initial exchange of ISAKMP Headers (con-
taining initiator and responder cookies) which would provide protection
against clogging (see section 2.5.3).
The defined exchanges are not meant to satisfy all DOI and key exchange
protocol requirements. If the defined exchanges meet the DOI require-
ments, then they can be used as outlined. If the defined exchanges do
not meet the security requirements defined by the DOI, then the DOI MUST
specify new exchange type(s) and the valid sequences of payloads that make
up a successful exchange, and how to build and interpret those payloads.
All ISAKMP implementations MUST implement the Informational Exchange and
SHOULD implement the other four exchanges. However, this is dependent on
the definition of the DOI and associated key exchange protocols.
As discussed above, these exchange types can be used in either phase of
negotiation. However, they may provide different security properties
in each of the phases. With each of these exchanges, the combination of
cookies and SPI fields identifies whether this exchange is being used in
the first or second phase of a negotiation.
4.3.1 Notation
The following notation is used to describe the ISAKMP exchange types,
shown in the next section, with the message formats and associated pay-
loads:
HDR is an ISAKMP header whose exchange type defines the payload orderings
SA is an SA negotiation payload with one or more Proposal and
Transform payloads. An initiator MAY provide multiple proposals
for negotiation; a responder MUST reply with only one.
KE is the key exchange payload.
IDx is the identity payload for "x". x can be: "ii" or "ir"
for the ISAKMP initiator and responder, respectively, or x can
be: "ui", "ur" (when the ISAKMP daemon is a proxy negotiator),
for the user initiator and responder, respectively.
HASH is the hash payload.
SIG is the signature payload. The data to sign is exchange-specific.
AUTH is a generic authentication mechanism, such as HASH or SIG.
NONCE is the nonce payload.
'*' signifies payload encryption after the ISAKMP header. This
encryption MUST begin immediately after the ISAKMP header and
all payloads following the ISAKMP header MUST be encrypted.
=> signifies "initiator to responder" communication
<= signifies "responder to initiator" communication
4.4 Base Exchange 4.4 Base Exchange
The Base Exchange is designed to allow the Key Exchange and Authentica- The Base Exchange is designed to allow the Key Exchange and Authentica-
tion related information to be transmitted together. Combining the Key tion related information to be transmitted together. Combining the Key
Exchange and Authentication-related information into one message reduces Exchange and Authentication-related information into one message reduces
the number of round-trips at the expense of not providing identity pro- the number of round-trips at the expense of not providing identity pro-
tection. Identity protection is not provided because identities are ex- tection. Identity protection is not provided because identities are ex-
changed before a common shared secret has been established and, therefore, changed before a common shared secret has been established and, therefore,
encryption of the identities is not possible. The following diagram shows encryption of the identities is not possible. The following diagram shows
skipping to change at page 49, line 43 skipping to change at page 51, line 29
an example of the Base Exchange. an example of the Base Exchange.
BASE EXCHANGE BASE EXCHANGE
_#______Initiator____Direction_____Responder______________________NOTE____________________ _#______Initiator____Direction_____Responder______________________NOTE____________________
(1) HDR; SA; NONCE => Begin ISAKMP-SA or Proxy negotiation (1) HDR; SA; NONCE => Begin ISAKMP-SA or Proxy negotiation
(2) <= HDR; SA; NONCE (2) <= HDR; SA; NONCE
Basic SA agreed upon Basic SA agreed upon
(3) HDR; KE; => (3) HDR; KE; =>
IDii; AUTH Key Generated IDii; AUTH Key Generated (by responder)
Initiator Identity Verified by Responder Initiator Identity Verified by Responder
(4) <= HDR; KE; (4) <= HDR; KE;
IDir; AUTH IDir; AUTH
Responder Identity Verified by Initiator Responder Identity Verified by Initiator
Key Generated Key Generated (by initiator)
SA established SA established
In the first message (1), the initiator generates a proposal it considers In the first message (1), the initiator generates a proposal it considers
adequate to protect traffic for the given situation. The Security Associ- adequate to protect traffic for the given situation. The Security Associ-
ation, Proposal, and Transform payloads are included in the Security Asso- ation, Proposal, and Transform payloads are included in the Security Asso-
ciation payload (for notation purposes). Random information which is used ciation payload (for notation purposes). Random information which is used
to guarantee liveness and protect against replay attacks is also trans- to guarantee liveness and protect against replay attacks is also trans-
mitted. Random information provided by both parties SHOULD be used by the mitted. Random information provided by both parties SHOULD be used by the
authentication mechanism to provide shared proof of participation in the authentication mechanism to provide shared proof of participation in the
exchange. exchange.
In the second message (2), the responder indicates the protection suite it In the second message (2), the responder indicates the protection suite it
has accepted with the Security Association, Proposal, and Transform pay- has accepted with the Security Association, Proposal, and Transform pay-
loads. Again, random information which is used to guarantee liveness and loads. Again, random information which is used to guarantee liveness and
protect against replay attacks is also transmitted. Random information protect against replay attacks is also transmitted. Random information
provide by both parties SHOULD be used by the authentication mechanism provided by both parties SHOULD be used by the authentication mechanism
to provide shared proof of participation in the exchange. Local secu- to provide shared proof of participation in the exchange. Local secu-
rity policy dictates the action of the responder if no proposed protection rity policy dictates the action of the responder if no proposed protection
suite is accepted. One possible action is the transmission of a Notify suite is accepted. One possible action is the transmission of a Notify
payload as part of an Informational Exchange. payload as part of an Informational Exchange.
In the third (3) and fourth (4) messages, the initiator and responder, re- In the third (3) and fourth (4) messages, the initiator and responder, re-
spectively, exchange keying material used to arrive at a common shared spectively, exchange keying material used to arrive at a common shared
secret and identification information. This information is transmitted secret and identification information. This information is transmitted
under the protection of the agreed upon authentication function. Local under the protection of the agreed upon authentication function. Local
security policy dictates the action if an error occurs during these mes- security policy dictates the action if an error occurs during these mes-
sages. One possible action is the transmission of a Notify payload as sages. One possible action is the transmission of a Notify payload as
part of an Informational Exchange. part of an Informational Exchange.
4.5 Identity Protection Exchange 4.5 Identity Protection Exchange
The Identity Protection Exchange is designed to separate the Key Exchange The Identity Protection Exchange is designed to separate the Key Exchange
information from the Identity and Authentication related information. information from the Identity and Authentication related information.
Separating the Key Exchange from the Identity and Authentication related Separating the Key Exchange from the Identity and Authentication related
information provides protection of the communicating identities at the ex- information provides protection of the communicating identities at the ex-
pense of an additional message. Identities are exchanged under the pro- pense of two additional messages. Identities are exchanged under the pro-
tection of a previously established common shared secret. The following tection of a previously established common shared secret. The following
diagram shows the messages with the possible payloads sent in each message diagram shows the messages with the possible payloads sent in each message
and notes for an example of the Identity Protection Exchange. and notes for an example of the Identity Protection Exchange.
IDENTITY PROTECTION EXCHANGE IDENTITY PROTECTION EXCHANGE
_#_______Initiator_____Direction______Responder_____NOTE______________________________________ _#_______Initiator_____Direction______Responder_____NOTE________________________________________
(1) HDR; SA => Begin ISAKMP-SA or Proxy negotiation (1) HDR; SA => Begin ISAKMP-SA or Proxy negotiation
(2) <= HDR; SA (2) <= HDR; SA
Basic SA agreed upon Basic SA agreed upon
(3) HDR; KE; NONCE => (3) HDR; KE; NONCE =>
(4) <= HDR; KE; NONCE (4) <= HDR; KE; NONCE
Key Generated Key Generated (by Initiator and Responder)
(5) HDR*; IDii; AUTH => (5) HDR*; IDii; AUTH =>
Initiator Identity Verified by Responder Initiator Identity Verified by Responder
(6) <= HDR*; IDir; AUTH (6) <= HDR*; IDir; AUTH
Responder Identity Verified by Initiator Responder Identity Verified by Initiator
SA established SA established
In the first message (1), the initiator generates a proposal it consid- In the first message (1), the initiator generates a proposal it consid-
ers adequate to protect traffic for the given situation. The Security As- ers adequate to protect traffic for the given situation. The Security As-
sociation, Proposal, and Transform payloads are included in the Security sociation, Proposal, and Transform payloads are included in the Security
Association payload (for notation purposes). Association payload (for notation purposes).
skipping to change at page 53, line 36 skipping to change at page 55, line 26
(2) <= HDR; SA; KE; (2) <= HDR; SA; KE;
NONCE; IDir; AUTH NONCE; IDir; AUTH
Initiator Identity Verified by Responder Initiator Identity Verified by Responder
Key Generated Key Generated
Basic SA agreed upon Basic SA agreed upon
(3) HDR*; AUTH => (3) HDR*; AUTH =>
Responder Identity Verified by Initiator Responder Identity Verified by Initiator
SA established SA established
In the first message (1), the initiator generates a proposal it consid- In the first message (1), the initiator generates a proposal it considers
ers adequate to protect traffic for the given situation. The Security adequate to protect traffic for the given situation. The Security Associ-
Association, Proposal, and Transform payloads are included in the Secu- ation, Proposal, and Transform payloads are included in the Security Asso-
rity Association payload (for notation purposes). Keying material used ciation payload (for notation purposes). There can be only one Proposal
to arrive at a common shared secret and random information which is used and one Transform offered (i.e. no choices) in order for the aggressive
to guarantee liveness and protect against replay attacks are also trans- exchange to work. Keying material used to arrive at a common shared se-
mitted. Random information provided by both parties SHOULD be used by the cret and random information which is used to guarantee liveness and pro-
authentication mechanism to provide shared proof of participation in the tect against replay attacks are also transmitted. Random information pro-
exchange. Additionally, the initiator transmits identification informa- vided by both parties SHOULD be used by the authentication mechanism to
tion. provide shared proof of participation in the exchange. Additionally, the
initiator transmits identification information.
In the second message (2), the responder indicates the protection suite In the second message (2), the responder indicates the protection suite
it has accepted with the Security Association, Proposal, and Transform it has accepted with the Security Association, Proposal, and Transform
payloads. Keying material used to arrive at a common shared secret and payloads. Keying material used to arrive at a common shared secret and
random information which is used to guarantee liveness and protect against random information which is used to guarantee liveness and protect against
replay attacks is also transmitted. Random information provided by both replay attacks is also transmitted. Random information provided by both
parties SHOULD be used by the authentication mechanism to provide shared parties SHOULD be used by the authentication mechanism to provide shared
proof of participation in the exchange. Additionally, the responder proof of participation in the exchange. Additionally, the responder
transmits identification information. All of this information is trans- transmits identification information. All of this information is trans-
mitted under the protection of the agreed upon authentication function. mitted under the protection of the agreed upon authentication function.
skipping to change at page 54, line 36 skipping to change at page 56, line 27
and notes for an example of the Informational Exchange. and notes for an example of the Informational Exchange.
INFORMATIONAL EXCHANGE INFORMATIONAL EXCHANGE
__#___Initiator__Direction_Responder_______________NOTE_______________ __#___Initiator__Direction_Responder_______________NOTE_______________
(1) HDR*; N/D => Error Notification or Deletion (1) HDR*; N/D => Error Notification or Deletion
In the first message (1), the initiator or responder transmits an ISAKMP In the first message (1), the initiator or responder transmits an ISAKMP
Notify or Delete payload. Notify or Delete payload.
If the Informational Exchange occurs during an ISAKMP Phase 1 negotiation If the Informational Exchange occurs prior to the exchange of keying me-
there will be no protection provided for the Informational Exchange. Once terial during an ISAKMP Phase 1 negotiation, there will be no protection
keying material has been exchanged or an ISAKMP SA has been established, provided for the Informational Exchange. Once keying material has been
the Informational Exchange MUST be transmitted under the protection pro- exchanged or an ISAKMP SA has been established, the Informational Exchange
vided by the keying material or the ISAKMP SA. MUST be transmitted under the protection provided by the keying material
or the ISAKMP SA.
All exchanges are similar in that with the beginning of any exchange cryp-
tographic synchronization MUST occur. The Informational Exchange is an
exchange and not an ISAKMP message. Thus, the generation of an Initial-
ization Vector (IV) for an Informational Exchange SHOULD be independent
of IVs of other on-going communication. This will ensure cryptographic
synchronization is maintained for existing communications and the Informa-
tional Exchange will be processed correctly.
5 ISAKMP Payload Processing 5 ISAKMP Payload Processing
Section 3 describes the ISAKMP payloads. These payloads are used in the Section 3 describes the ISAKMP payloads. These payloads are used in the
exchanges described in section 4 and can be used in exchanges defined for exchanges described in section 4 and can be used in exchanges defined for
a specific DOI. This section describes the processing for each of the a specific DOI. This section describes the processing for each of the
payloads. This section suggests the logging of events to a system au- payloads. This section suggests the logging of events to a system au-
dit file. This action is controlled by a system security policy and is, dit file. This action is controlled by a system security policy and is,
therefore, only a suggested action. therefore, only a suggested action.
5.1 General Message Processing 5.1 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. All processing SHOULD include packet length checks to insure
the packet received is at least as long as the length given in the ISAKMP
Header.
When transmitting an ISAKMP message, the transmitting entity (initiator or When transmitting an ISAKMP message, the transmitting entity (initiator or
responder) MUST do the following: responder) MUST do the following:
1. Set a timer and initialize a retry counter. 1. Set a timer and initialize a retry counter.
2. If the timer expires, the ISAKMP message is resent and the retry 2. If the timer expires, the ISAKMP message is resent and the retry
counter is decremented. counter is decremented.
3. If the retry counter reaches zero (0), the event, RETRY LIMIT 3. If the retry counter reaches zero (0), the event, RETRY LIMIT
REACHED, is logged in the appropriate system audit file. REACHED, MAY be logged in the appropriate system audit file.
4. The ISAKMP protocol machine clears all states and returns to IDLE. 4. The ISAKMP protocol machine clears all states and returns to IDLE.
5.2 ISAKMP Header Processing 5.2 ISAKMP Header Processing
When creating an ISAKMP message, the transmitting entity MUST do the fol- When creating an ISAKMP message, the transmitting entity (initiator or
lowing: responder) MUST do the following:
1. Create the respective cookie. See section 2.5.3 for details. 1. Create the respective cookie. See section 2.5.3 for details.
2. Determine the relevant security characteristics of the session (i.e. 2. Determine the relevant security characteristics of the session (i.e.
DOI and situation). DOI and situation).
3. Construct an ISAKMP Header with fields as described in section 3.1. 3. Construct an ISAKMP Header with fields as described in section 3.1.
4. Construct other ISAKMP payloads, depending on the exchange type. 4. Construct other ISAKMP payloads, depending on the exchange type.
5. Transmit the message to the destination host as described in section 5. Transmit the message to the destination host as described in section
5.1. 5.1.
When an ISAKMP message is received, the receiving entity (initiator or When an ISAKMP message is received, the receiving entity (initiator or
responder) MUST do the following: responder) MUST do the following:
1. Verify the Initiator and Responder ``cookies''. If the cookie 1. Verify the Initiator and Responder ``cookies''. If the cookie
validation fails, the message is discarded and the following actions validation fails, the message is discarded and the following actions
are taken: are taken:
(a) The event, INVALID COOKIE, is logged in the appropriate system (a) The event, INVALID COOKIE, MAY be logged in the appropriate
audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-COOKIE message type MAY be sent to the initiating the INVALID-COOKIE message type MAY be sent to the transmitting
entity. This action is dictated by a system security policy. entity. This action is dictated by a system security policy.
2. Check the Next Payload field to confirm it is valid. If the Next 2. Check the Next Payload field to confirm it is valid. If the Next
Payload field validation fails, the message is discarded and the Payload field validation fails, the message is discarded and the
following actions are taken: following actions are taken:
(a) The event, INVALID NEXT PAYLOAD, is logged in the appropriate (a) The event, INVALID NEXT PAYLOAD, MAY be logged in the appropriate
system audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-PAYLOAD-TYPE message type MAY be sent to the initiat- the INVALID-PAYLOAD-TYPE message type MAY be sent to the
ing entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
3. Check the Major and Minor Version fields to confirm they are correct. 3. Check the Major and Minor Version fields to confirm they are correct.
If the Version field validation fails, the message is discarded and If the Version field validation fails, the message is discarded and
the following actions are taken: the following actions are taken:
(a) The event, INVALID ISAKMP VERSION, is logged in the appropriate (a) The event, INVALID ISAKMP VERSION, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-MAJOR-VERSION or INVALID-MINOR-VERSION message type the INVALID-MAJOR-VERSION or INVALID-MINOR-VERSION message type
MAY be sent to the initiating entity. This action is dictated by MAY be sent to the transmitting entity. This action is dictated
a system security policy. by a system security policy.
4. Check the Exchange Type field to confirm it is valid. If the 4. Check the Exchange Type field to confirm it is valid. If the
Exchange Type field validation fails, the message is discarded and Exchange Type field validation fails, the message is discarded and
the following actions are taken: the following actions are taken:
(a) The event, INVALID EXCHANGE TYPE, is logged in the appropriate (a) The event, INVALID EXCHANGE TYPE, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-EXCHANGE-TYPE message type MAY be sent to the the INVALID-EXCHANGE-TYPE message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
5. Check the Flags field to ensure it contains correct values. If the 5. Check the Flags field to ensure it contains correct values. If the
Flags field validation fails, the message is discarded and the Flags field validation fails, the message is discarded and the
following actions are taken: following actions are taken:
(a) The event, INVALID FLAGS, is logged in the appropriate system (a) The event, INVALID FLAGS, MAY be logged in the appropriate system
audit file. audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-FLAGS message type MAY be sent to the initiating the INVALID-FLAGS message type MAY be sent to the transmitting
entity. This action is dictated by a system security policy. entity. This action is dictated by a system security policy.
6. Check the Message ID field to ensure it contains correct values. If 6. Check the Message ID field to ensure it contains correct values. If
the Message ID validation fails, the message is discarded and the the Message ID validation fails, the message is discarded and the
following actions are taken: following actions are taken:
(a) The event, INVALID MESSAGE ID, is logged in the appropriate (a) The event, INVALID MESSAGE ID, MAY be logged in the appropriate
system audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-MESSAGE-ID message type MAY be sent to the initiating the INVALID-MESSAGE-ID message type MAY be sent to the
entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
7. Processing of the ISAKMP message continues using the value in the 7. Processing of the ISAKMP message continues using the value in the
Next Payload field. Next Payload field.
5.3 Generic Payload Header Processing 5.3 Generic Payload Header Processing
When creating any of the ISAKMP Payloads described in sections 5.4 through When creating any of the ISAKMP Payloads described in sections 3.4 through
5.13 a Generic Payload Header is placed at the beginning of these pay- 3.15 a Generic Payload Header is placed at the beginning of these pay-
loads. When creating the Generic Payload Header, the transmitting entity loads. When creating the Generic Payload Header, the transmitting entity
MUST do the following: (initiator or responder) MUST do the following:
1. Place the value of the Next Payload in the Next Payload field. These 1. Place the value of the Next Payload in the Next Payload field. These
values are described in section 3.1. values are described in section 3.1.
2. Place the value zero (0) in the RESERVED field. 2. Place the value zero (0) in the RESERVED field.
3. Place the length (in octets) of the payload in the Payload Length 3. Place the length (in octets) of the payload in the Payload Length
field. field.
4. Construct the payloads as defined in the remainder of this section. 4. Construct the payloads as defined in the remainder of this section.
When any of the ISAKMP Payloads are received, the receiving entity (ini- When any of the ISAKMP Payloads are received, the receiving entity (ini-
tiator or responder) MUST do the following: tiator or responder) MUST do the following:
1. Check the Next Payload field to confirm it is valid. If the Next 1. Check the Next Payload field to confirm it is valid. If the Next
Payload field validation fails, the message is discarded and the Payload field validation fails, the message is discarded and the
following actions are taken: following actions are taken:
(a) The event, INVALID NEXT PAYLOAD, is logged in the appropriate (a) The event, INVALID NEXT PAYLOAD, MAY be logged in the appropriate
system audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-PAYLOAD-TYPE message type MAY be sent to the initiat- the INVALID-PAYLOAD-TYPE message type MAY be sent to the
ing entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
2. Verify the RESERVED field contains the value zero. If the value in 2. Verify the RESERVED field contains the value zero. If the value in
the RESERVED field is not zero, the message is discarded and the the RESERVED field is not zero, the message is discarded and the
following actions are taken: following actions are taken:
(a) The event, INVALID RESERVED FIELD, is logged in the appropriate (a) The event, INVALID RESERVED FIELD, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the BAD-PROPOSAL-SYNTAX or PAYLOAD-MALFORMED message type MAY be the BAD-PROPOSAL-SYNTAX or PAYLOAD-MALFORMED message type MAY be
sent to the initiating entity. This action is dictated by a sent to the transmitting entity. This action is dictated by a
system security policy. system security policy.
3. Process the remaining payloads as defined by the Next Payload field. 3. Process the remaining payloads as defined by the Next Payload field.
5.4 Security Association Payload Processing 5.4 Security Association Payload Processing
When creating a Security Association Payload, the transmitting entity MUST When creating a Security Association Payload, the transmitting entity
do the following: (initiator or responder) MUST do the following:
1. Determine the Domain of Interpretation for which this negotiation is 1. Determine the Domain of Interpretation for which this negotiation is
being performed. being performed.
2. Determine the situation within the determined DOI for which this 2. Determine the situation within the determined DOI for which this
negotiation is being performed. negotiation is being performed.
3. Determine the proposal(s) and transform(s) within the situation. 3. Determine the proposal(s) and transform(s) within the situation.
These are described, respectively, in sections 3.5, 5.4.1, 3.6, and These are described, respectively, in sections 3.5 and 3.6.
5.4.2.
4. Construct a Security Association payload. 4. Construct a Security Association payload.
5. Transmit the message to the receiving entity as described in section 5. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Security Association payload is received, the receiving entity When a Security Association payload is received, the receiving entity
(initiator or responder) MUST do the following: (initiator or responder) MUST do the following:
1. Determine if the Domain of Interpretation (DOI) is supported. If the 1. Determine if the Domain of Interpretation (DOI) is supported. If the
DOI determination fails, the message is discarded and the following DOI determination fails, the message is discarded and the following
actions are taken: actions are taken:
(a) The event, INVALID DOI, is logged in the appropriate system audit (a) The event, INVALID DOI, MAY be logged in the appropriate system
file. audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the DOI-NOT-SUPPORTED message type MAY be sent to the initiating the DOI-NOT-SUPPORTED message type MAY be sent to the
entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
2. Determine if the given situation can be protected. If the Situation 2. Determine if the given situation can be protected. If the Situation
determination fails, the message is discarded and the following determination fails, the message is discarded and the following
actions are taken: actions are taken:
(a) The event, INVALID SITUATION, is logged in the appropriate system (a) The event, INVALID SITUATION, MAY be logged in the appropriate
audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the SITUATION-NOT-SUPPORTED message type MAY be sent to the the SITUATION-NOT-SUPPORTED message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
3. Process the remaining payloads (i.e. Proposal, Transform) of the 3. Process the remaining payloads (i.e. Proposal, Transform) of the
Security Association Payload. If the Security Association Proposal Security Association Payload. If the Security Association Proposal
(as described in sections 5.4.1 and 5.4.2) is not accepted, then the (as described in sections 5.5 and 5.6) is not accepted, then the
following actions are taken: following actions are taken:
(a) The event, INVALID PROPOSAL, is logged in the appropriate system (a) The event, INVALID PROPOSAL, MAY be logged in the appropriate
audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the NO-PROPOSAL-CHOSEN message type MAY be sent to the initiating the NO-PROPOSAL-CHOSEN message type MAY be sent to the
entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
5.4.1 Proposal Payload Processing 5.5 Proposal Payload Processing
When creating a Proposal Payload, the transmitting entity MUST do the fol- When creating a Proposal Payload, the transmitting entity (initiator or
lowing: responder) MUST do the following:
1. Determine the Protocol for this proposal. 1. Determine the Protocol for this proposal.
2. Determine the number of proposals to be offered for this protocol and 2. Determine the number of proposals to be offered for this protocol and
the number of transforms for each proposal. Transforms are described the number of transforms for each proposal. Transforms are described
in sections 3.6 and 5.4.2. in section 3.6.
3. Generate a unique pseudo-random SPI. 3. Generate a unique pseudo-random SPI.
4. Construct a Proposal payload. 4. Construct a Proposal payload.
When a Proposal payload is received, the receiving entity (initiator or When a Proposal payload is received, the receiving entity (initiator or
responder) MUST do the following: responder) MUST do the following:
1. Determine if the Protocol is supported. If the Protocol-ID field is 1. Determine if the Protocol is supported. If the Protocol-ID field is
invalid, the message is discarded and the following actions are invalid, the payload is discarded and the following actions are
taken: taken:
(a) The event, INVALID PROTOCOL, is logged in the appropriate system (a) The event, INVALID PROTOCOL, MAY be logged in the appropriate
audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-PROTOCOL-ID message type MAY be sent to the initiat- the INVALID-PROTOCOL-ID message type MAY be sent to the
ing entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
2. Determine if the SPI is valid. If the SPI is invalid, the message is 2. Determine if the SPI is valid. If the SPI is invalid, the payload is
discarded and the following actions are taken: discarded and the following actions are taken:
(a) The event, INVALID SPI, is logged in the appropriate system audit (a) The event, INVALID SPI, MAY be logged in the appropriate system
file. audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-SPI message type MAY be sent to the initiating the INVALID-SPI message type MAY be sent to the transmitting
entity. This action is dictated by a system security policy. entity. This action is dictated by a system security policy.
3. Ensure the Proposals are presented according to the details given in 3. Ensure the Proposals are presented according to the details given in
section 3.5 and 4.1. If the proposals are not formed correctly, the section 3.5 and 4.2. If the proposals are not formed correctly, the
following actions are taken: following actions are taken:
(a) Possible events, BAD PROPOSAL SYNTAX, INVALID PROPOSAL, are (a) Possible events, BAD PROPOSAL SYNTAX, INVALID PROPOSAL, are
logged in the appropriate system audit file. logged in the appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the BAD-PROPOSAL-SYNTAX or PAYLOAD-MALFORMED message type MAY be the BAD-PROPOSAL-SYNTAX or PAYLOAD-MALFORMED message type MAY be
sent to the initiating entity. This action is dictated by a sent to the transmitting entity. This action is dictated by a
system security policy. system security policy.
4. Process the Proposal and Transform payloads as defined by the Next 4. Process the Proposal and Transform payloads as defined by the Next
Payload field. Examples of processing these payloads is given in Payload field. Examples of processing these payloads are given in
section 4.1.1. section 4.2.1.
5.4.2 Transform Payload Processing 5.6 Transform Payload Processing
When creating a Transform Payload, the transmitting entity MUST do the When creating a Transform Payload, the transmitting entity (initiator or
following: responder) MUST do the following:
1. Determine the Transform # for this transform. 1. Determine the Transform # for this transform.
2. Determine the number of transforms to be offered for this proposal. 2. Determine the number of transforms to be offered for this proposal.
Transforms are described in sections 3.6. Transforms are described in sections 3.6.
3. Construct a Transform payload. 3. Construct a Transform payload.
When a Transform payload is received, the receiving entity (initiator or When a Transform payload is received, the receiving entity (initiator or
responder) MUST do the following: responder) MUST do the following:
1. Determine if the Transform is supported. If the Transform-ID field 1. Determine if the Transform is supported. If the Transform-ID field
is invalid, the message is discarded and the following actions are contains an unknown or unsupported value, then that Transform payload
taken: MUST be ignored and MUST NOT cause the generation of an INVALID
TRANSFORM event. If the Transform-ID field is invalid, the payload
is discarded and the following actions are taken:
(a) The event, INVALID TRANSFORM, is logged in the appropriate system (a) The event, INVALID TRANSFORM, MAY be logged in the appropriate
audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-TRANSFORM-ID message type MAY be sent to the initiat- the INVALID-TRANSFORM-ID message type MAY be sent to the
ing entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
2. Ensure the Transforms are presented according to the details given in 2. Ensure the Transforms are presented according to the details given in
section 3.6 and 4.1. If the transforms are not formed correctly, the section 3.6 and 4.2. If the transforms are not formed correctly, the
following actions are taken: following actions are taken:
(a) Possible events, BAD PROPOSAL SYNTAX, INVALID TRANSFORM, INVALID (a) Possible events, BAD PROPOSAL SYNTAX, INVALID TRANSFORM, INVALID
ATTRIBUTES, are logged in the appropriate system audit file. ATTRIBUTES, are logged in the appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the BAD-PROPOSAL-SYNTAX, PAYLOAD-MALFORMED or ATTRIBUTES-NOT- the BAD-PROPOSAL-SYNTAX, PAYLOAD-MALFORMED or ATTRIBUTES-NOT-
SUPPORTED message type MAY be sent to the initiating entity. SUPPORTED message type MAY be sent to the transmitting entity.
This action is dictated by a system security policy. This action is dictated by a system security policy.
3. Process the subsequent Transform and Proposal payloads as defined by 3. Process the subsequent Transform and Proposal payloads as defined by
the Next Payload field. Examples of processing these payloads is the Next Payload field. Examples of processing these payloads are
given in section 4.1.1. given in section 4.2.1.
5.5 Key Exchange Payload Processing 5.7 Key Exchange Payload Processing
When creating a Key Exchange Payload, the transmitting entity MUST do the When creating a Key Exchange Payload, the transmitting entity (initiator
following: or responder) MUST do the following:
1. Determine the Key Exchange to be used as defined by the DOI. 1. Determine the Key Exchange to be used as defined by the DOI.
2. Determine the usage of the Key Exchange Data field as defined by the 2. Determine the usage of the Key Exchange Data field as defined by the
DOI. DOI.
3. Construct a Key Exchange payload. 3. Construct a Key Exchange payload.
4. Transmit the message to the receiving entity as described in section 4. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Key Exchange payload is received, the receiving entity (initiator When a Key Exchange payload is received, the receiving entity (initiator
or responder) MUST do the following: or responder) MUST do the following:
1. Determine if the Key Exchange is supported. If the Key Exchange 1. Determine if the Key Exchange is supported. If the Key Exchange
determination fails, the message is discarded and the following determination fails, the message is discarded and the following
actions are taken: actions are taken:
(a) The event, INVALID KEY INFORMATION, is logged in the appropriate (a) The event, INVALID KEY INFORMATION, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-KEY-INFORMATION message type MAY be sent to the the INVALID-KEY-INFORMATION message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
5.6 Identification Payload Processing 5.8 Identification Payload Processing
When creating an Identification Payload, the transmitting entity MUST do When creating an Identification Payload, the transmitting entity (initia-
the following: tor or responder) MUST do the following:
1. Determine the Identification information to be used as defined by the 1. Determine the Identification information to be used as defined by the
DOI (and possibly the situation). DOI (and possibly the situation).
2. Determine the usage of the Identification Data field as defined by 2. Determine the usage of the Identification Data field as defined by
the DOI. the DOI.
3. Construct an Identification payload. 3. Construct an Identification payload.
4. Transmit the message to the receiving entity as described in section 4. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When an Identification payload is received, the receiving entity (initia- When an Identification payload is received, the receiving entity (initia-
tor or responder) MUST do the following: tor or responder) MUST do the following:
1. Determine if the Identification Type is supported. This may be based 1. Determine if the Identification Type is supported. This may be based
on the DOI and Situation. If the Identification determination fails, on the DOI and Situation. If the Identification determination fails,
the message is discarded and the following actions are taken: the message is discarded and the following actions are taken:
(a) The event, INVALID ID INFORMATION, is logged in the appropriate (a) The event, INVALID ID INFORMATION, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-ID-INFORMATION message type MAY be sent to the the INVALID-ID-INFORMATION message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
5.7 Certificate Payload Processing 5.9 Certificate Payload Processing
When creating a Certificate Payload, the transmitting entity MUST do the When creating a Certificate Payload, the transmitting entity (initiator or
following: responder) MUST do the following:
1. Determine the Certificate Encoding to be used. This may be specified 1. Determine the Certificate Encoding to be used. This may be specified
by the DOI. by the DOI.
2. Ensure the existence of a certificate formatted as defined by the 2. Ensure the existence of a certificate formatted as defined by the
Certificate Encoding. Certificate Encoding.
3. Construct a Certificate payload. 3. Construct a Certificate payload.
4. Transmit the message to the receiving entity as described in section 4. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Certificate payload is received, the receiving entity (initiator or When a Certificate payload is received, the receiving entity (initiator or
responder) MUST do the following: responder) MUST do the following:
1. Determine if the Certificate Encoding is supported. If the 1. Determine if the Certificate Encoding is supported. If the
Certificate Encoding is not supported, the message is discarded and Certificate Encoding is not supported, the payload is discarded and
the following actions are taken: the following actions are taken:
(a) The event, INVALID CERTIFICATE TYPE, is logged in the appropriate (a) The event, INVALID CERTIFICATE TYPE, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-CERT-ENCODING message type MAY be sent to the the INVALID-CERT-ENCODING message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
2. Process the Certificate Data field. If the Certificate Data is 2. Process the Certificate Data field. If the Certificate Data is
invalid or improperly formatted, the message is discarded and the invalid or improperly formatted, the payload is discarded and the
following actions are taken: following actions are taken:
(a) The event, INVALID CERTIFICATE, is logged in the appropriate (a) The event, INVALID CERTIFICATE, MAY be logged in the appropriate
system audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-CERTIFICATE message type MAY be sent to the initiat- the INVALID-CERTIFICATE message type MAY be sent to the
ing entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
5.8 Certificate Request Payload Processing 5.10 Certificate Request Payload Processing
When creating a Certificate Request Payload, the transmitting entity MUST When creating a Certificate Request Payload, the transmitting entity (ini-
do the following: tiator or responder) MUST do the following:
1. Determine the number and types of acceptable Certificate Encodings to 1. Determine the type of Certificate Encoding to be requested. This may
be requested. This may be specified by the DOI. be specified by the DOI.
2. Determine the number and names of Certificate Authorities which are 2. Determine the name of an acceptable Certificate Authority which is to
acceptable and are to be requested. be requested (if applicable).
3. Construct a Certificate Request payload. 3. Construct a Certificate Request payload.
4. Transmit the message to the receiving entity as described in section 4. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Certificate Request payload is received, the receiving entity (ini- When a Certificate Request payload is received, the receiving entity (ini-
tiator or responder) MUST do the following: tiator or responder) MUST do the following:
1. Ensure that the # of Certificate Types and the actual values 1. Determine if the Certificate Encoding is supported. If the
contained in the Certificate Types field are equivalent. If not, Certificate Encoding is invalid, the payload is discarded and the
then the following actions are taken: following actions are taken:
(a) The event, BAD CERTIFICATE REQUEST SYNTAX, is logged in the (a) The event, INVALID CERTIFICATE TYPE, MAY be logged in the
appropriate system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the BAD-CERT-REQUEST-SYNTAX message type MAY be sent to the the INVALID-CERT-ENCODING message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
2. Determine if the Certificate Types are supported. If any of the If the Certificate Encoding is not supported, the payload is
Certificate Types are not supported, the message is discarded and the discarded and the following actions are taken:
following actions are taken:
(a) The event, INVALID CERTIFICATE TYPE, is logged in the appropriate (a) The event, CERTIFICATE TYPE UNSUPPORTED, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-CERT-ENCODING message type MAY be sent to the the CERT-TYPE-UNSUPPORTED message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
3. Ensure that the # of Certificate Authorities and the actual values 2. Determine if the Certificate Authority is supported for the specified
contained in the Certificate Authorities field are equivalent. If Certificate Encoding. If the Certificate Authority is invalid or
not, then the following actions are taken: improperly formatted, the payload is discarded and the following
actions are taken:
(a) The event, BAD CERTIFICATE REQUEST SYNTAX, is logged in the (a) The event, INVALID CERTIFICATE AUTHORITY, MAY be logged in the
appropriate system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the BAD-CERT-REQUEST-SYNTAX message type MAY be sent to the the INVALID-CERT-AUTHORITY message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
4. Process the Certificate Authorities field. If the Certificate 3. Process the Certificate Request. If a requested Certificate Type
Authorities are invalid or improperly formatted, the message is with the specified Certificate Authority is not available, then the
discarded and the following actions are taken: payload is discarded and the following actions are taken:
(a) The event, INVALID CERTIFICATE AUTHORITIES, is logged in the (a) The event, CERTIFICATE-UNAVAILABLE, MAY be logged in the
appropriate system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-CERT-AUTHORITY message type MAY be sent to the the CERTIFICATE-UNAVAILABLE message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
5.9 Hash Payload Processing 5.11 Hash Payload Processing
When creating a Hash Payload, the transmitting entity MUST do the follow- When creating a Hash Payload, the transmitting entity (initiator or re-
ing: sponder) MUST do the following:
1. Determine the Hash function to be used as defined by the SA 1. Determine the Hash function to be used as defined by the SA
negotiation. negotiation.
2. Determine the usage of the Hash Data field as defined by the DOI. 2. Determine the usage of the Hash Data field as defined by the DOI.
3. Construct a Hash payload. 3. Construct a Hash payload.
4. Transmit the message to the receiving entity as described in section 4. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Hash payload is received, the receiving entity (initiator or re- When a Hash payload is received, the receiving entity (initiator or re-
sponder) MUST do the following: sponder) MUST do the following:
1. Determine if the Hash is supported. If the Hash determination fails, 1. Determine if the Hash is supported. If the Hash determination fails,
the message is discarded and the following actions are taken: the message is discarded and the following actions are taken:
(a) The event, INVALID HASH INFORMATION, is logged in the appropriate (a) The event, INVALID HASH INFORMATION, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-HASH-INFORMATION message type MAY be sent to the the INVALID-HASH-INFORMATION message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
2. Perform the Hash function as outlined in the DOI and/or Key Exchange 2. Perform the Hash function as outlined in the DOI and/or Key Exchange
protocol documents. If the Hash function fails, the message is protocol documents. If the Hash function fails, the message is
discarded and the following actions are taken: discarded and the following actions are taken:
(a) The event, INVALID HASH VALUE, is logged in the appropriate (a) The event, INVALID HASH VALUE, MAY be logged in the appropriate
system audit file. system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the AUTHENTICATION-FAILED message type MAY be sent to the the AUTHENTICATION-FAILED message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
5.10 Signature Payload Processing 5.12 Signature Payload Processing
When creating a Signature Payload, the transmitting entity MUST do the When creating a Signature Payload, the transmitting entity (initiator or
following: responder) MUST do the following:
1. Determine the Signature function to be used as defined by the SA 1. Determine the Signature function to be used as defined by the SA
negotiation. negotiation.
2. Determine the usage of the Signature Data field as defined by the 2. Determine the usage of the Signature Data field as defined by the
DOI. DOI.
3. Construct a Signature payload. 3. Construct a Signature payload.
4. Transmit the message to the receiving entity as described in section 4. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Signature payload is received, the receiving entity (initiator or When a Signature payload is received, the receiving entity (initiator or
responder) MUST do the following: responder) MUST do the following:
1. Determine if the Signature is supported. If the Signature 1. Determine if the Signature is supported. If the Signature
determination fails, the message is discarded and the following determination fails, the message is discarded and the following
actions are taken: actions are taken:
(a) The event, INVALID SIGNATURE INFORMATION, is logged in the (a) The event, INVALID SIGNATURE INFORMATION, MAY be logged in the
appropriate system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the INVALID-SIGNATURE message type MAY be sent to the initiating the INVALID-SIGNATURE message type MAY be sent to the
entity. This action is dictated by a system security policy. transmitting entity. This action is dictated by a system
security policy.
2. Perform the Signature function as outlined in the DOI and/or Key 2. Perform the Signature function as outlined in the DOI and/or Key
Exchange protocol documents. If the Signature function fails, the Exchange protocol documents. If the Signature function fails, the
message is discarded and the following actions are taken: message is discarded and the following actions are taken:
(a) The event, INVALID SIGNATURE VALUE, is logged in the appropriate (a) The event, INVALID SIGNATURE VALUE, MAY be logged in the
system audit file. appropriate system audit file.
(b) An Informational Exchange with a Notification payload containing (b) An Informational Exchange with a Notification payload containing
the AUTHENTICATION-FAILED message type MAY be sent to the the AUTHENTICATION-FAILED message type MAY be sent to the
initiating entity. This action is dictated by a system security transmitting entity. This action is dictated by a system
policy. security policy.
5.11 Nonce Payload Processing 5.13 Nonce Payload Processing
When creating a Nonce Payload, the transmitting entity MUST do the follow- When creating a Nonce Payload, the transmitting entity (initiator or re-
ing: sponder) MUST do the following:
1. Create a unique random value to be used as a nonce. 1. Create a unique random value to be used as a nonce.
2. Construct a Nonce payload. 2. Construct a Nonce payload.
3. Transmit the message to the receiving entity as described in section 3. Transmit the message to the receiving entity as described in section
5.1. 5.1.
When a Nonce payload is received, the receiving entity (initiator or re- When a Nonce payload is received, the receiving entity (initiator or re-
sponder) MUST do the following: sponder) MUST do the following:
1. There are no specific procedures for handling Nonce payloads. The 1. There are no specific procedures for handling Nonce payloads. The
procedures are defined by the exchange types (and possibly the DOI procedures are defined by the exchange types (and possibly the DOI
and Key Exchange descriptions). and Key Exchange descriptions).
5.12 Notification Payload Processing 5.14 Notification Payload Processing
During communications it is possible that errors may occur. The Infor- During communications it is possible that errors may occur. The Infor-
mational Exchange with a Notify Payload provides a controlled method of mational Exchange with a Notify Payload provides a controlled method of
informing a peer entity that errors have occurred during protocol process- informing a peer entity that errors have occurred during protocol process-
ing. ing. It is RECOMMENDED that Notify Payloads be sent in a separate Infor-
mational Exchange rather than appending a Notify Payload to an existing
exchange.
When creating a Notification Payload, the transmitting entity MUST do the When creating a Notification Payload, the transmitting entity (initiator
following: or responder) MUST do the following:
1. Determine the DOI for this Notification. 1. Determine the DOI for this Notification.
2. Determine the Protocol-ID for this Notification. 2. Determine the Protocol-ID for this Notification.
3. Determine the SPI size based on the Protocol-ID field. This field is 3. Determine the SPI size based on the Protocol-ID field. This field is
necessary because different security protocols have different SPI necessary because different security protocols have different SPI
sizes. For example, ISAKMP combines the Initiator and Responder sizes. For example, ISAKMP combines the Initiator and Responder
cookie pair (16 octets) as a SPI, while ESP and AH have 8 octet SPIs. cookie pair (16 octets) as a SPI, while ESP and AH have 8 octet SPIs.
skipping to change at page 69, line 44 skipping to change at page 72, line 7
terial during an ISAKMP Phase 1 negotiation there will be no protection terial during an ISAKMP Phase 1 negotiation there will be no protection
provided for the Informational Exchange. Once the keying material has provided for the Informational Exchange. Once the keying material has
been exchanged or the ISAKMP SA has been established, the Informational been exchanged or the ISAKMP SA has been established, the Informational
Exchange MUST be transmitted under the protection provided by the keying Exchange MUST be transmitted under the protection provided by the keying
material or the ISAKMP SA. material or the ISAKMP SA.
When a Notification payload is received, the receiving entity (initiator When a Notification payload is received, the receiving entity (initiator
or responder) MUST do the following: or responder) MUST do the following:
1. Determine if the Informational Exchange has any protection applied to 1. Determine if the Informational Exchange has any protection applied to
it by checking the Encryption Bit in the ISAKMP Header. If the it by checking the Encryption Bit and the Authentication Only Bit in
Informational Exchange is not encrypted the payload processing can the ISAKMP Header. If the Encryption Bit is set, i.e. the Informa-
continue as described below. If the Informational Exchange is tional Exchange is encrypted, then the message MUST be decrypted
encrypted, then the message MUST be decrypted using the (in-progress using the (in-progress or completed) ISAKMP SA. Once the decryption
or completed) ISAKMP SA. Once the decryption is complete the is complete the processing can continue as described below. If the
processing can continue as described below. Authentication Only Bit is set, then the message MUST be authenti-
cated using the (in-progress or completed) ISAKMP SA. Once the
authentication is completed, the processing can continue as described
below. If the Informational Exchange is not encrypted or authentica-
tion, the payload processing can continue as described below.
2. Determine if the Domain of Interpretation (DOI) is supported. If the 2. Determine if the Domain of Interpretation (DOI) is supported. If the
DOI determination fails, the message is discarded and the following DOI determination fails, the payload is discarded and the following
action is taken: action is taken:
(a) The event, INVALID DOI, is logged in the appropriate system audit (a) The event, INVALID DOI, MAY be logged in the appropriate system
file. audit file.
3. Determine if the Protocol-Id is supported. If the Protocol-Id 3. Determine if the Protocol-Id is supported. If the Protocol-Id
determination fails, the message is discarded and the following determination fails, the payload is discarded and the following
action is taken: action is taken:
(a) The event, INVALID PROTOCOL-ID, is logged in the appropriate (a) The event, INVALID PROTOCOL-ID, MAY be logged in the appropriate
system audit file. system audit file.
4. Determine if the SPI is valid. If the SPI is invalid, the message is 4. Determine if the SPI is valid. If the SPI is invalid, the payload is
discarded and the following action is taken: discarded and the following action is taken:
(a) The event, INVALID SPI, is logged in the appropriate system audit (a) The event, INVALID SPI, MAY be logged in the appropriate system
file. audit file.
5. Determine if the Notify Message Type is valid. If the Notify Message 5. Determine if the Notify Message Type is valid. If the Notify Message
Type is invalid, the message is discarded and the following action is Type is invalid, the payload is discarded and the following action is
taken: taken:
(a) The event, INVALID MESSAGE TYPE, is logged in the appropriate (a) The event, INVALID MESSAGE TYPE, MAY be logged in the appropriate
system audit file. system audit file.
6. Process the Notification payload, including additional Notification 6. Process the Notification payload, including additional Notification
Data, and take appropriate action, according to local security Data, and take appropriate action, according to local security
policy. policy.
5.13 Delete Payload Processing 5.15 Delete Payload Processing
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 establish a new SA and delete the compromised, then it is necessary to establish a new SA and delete the
current SA. current SA.
The Informational Exchange with a Delete Payload provides a controlled The Informational Exchange with a Delete Payload provides a controlled
method of informing a peer entity that the initiating entity has deleted method of informing a peer entity that the transmitting entity has deleted
the SA(s). Deletion of Security Associations MUST always be performed the SA(s). Deletion of Security Associations MUST always be performed un-
under the protection of an ISAKMP SA. The receiving entity SHOULD clean up der the protection of an ISAKMP SA. The receiving entity SHOULD clean up
its local SA database. However, upon receipt of a Delete message the SAs its local SA database. However, upon receipt of a Delete message the SAs
listed in the Security Parameter Index (SPI) field of the Delete payload listed in the Security Parameter Index (SPI) field of the Delete payload
cannot be used with the initiating entity. The SA Establishment procedure cannot be used with the transmitting entity. The SA Establishment proce-
must be invoked to re-establish secure communications. dure must be invoked to re-establish secure communications.
When creating a Delete Payload, the transmitting entity MUST do the fol- When creating a Delete Payload, the transmitting entity (initiator or re-
lowing: sponder) MUST do the following:
1. Determine the DOI for this Deletion. 1. Determine the DOI for this Deletion.
2. Determine the Protocol-ID for this Deletion. 2. Determine the Protocol-ID for this Deletion.
3. Determine the SPI size based on the Protocol-ID field. This field is 3. Determine the SPI size based on the Protocol-ID field. This field is
necessary because different security protocols have different SPI necessary because different security protocols have different SPI
sizes. For example, ISAKMP combines the Initiator and Responder sizes. For example, ISAKMP combines the Initiator and Responder
cookie pair (16 octets) as a SPI, while ESP and AH have 8 octet SPIs. cookie pair (16 octets) as a SPI, while ESP and AH have 8 octet SPIs.
skipping to change at page 71, line 40 skipping to change at page 74, line 12
policy will dictate the procedures for continuing. However, we RECOMMEND policy will dictate the procedures for continuing. However, we RECOMMEND
that a DELETE PAYLOAD ERROR event be logged in the appropriate system au- that a DELETE PAYLOAD ERROR event be logged in the appropriate system au-
dit file by the receiving entity. dit file by the receiving entity.
As described above, the Informational Exchange with a Delete payload MUST As described above, the Informational Exchange with a Delete payload MUST
be transmitted under the protection provided by an ISAKMP SA. be transmitted under the protection provided by an ISAKMP SA.
When a Delete payload is received, the receiving entity (initiator or re- When a Delete payload is received, the receiving entity (initiator or re-
sponder) MUST do the following: sponder) MUST do the following:
1. Because the Informational Exchange is encrypted, then the message 1. Because the Informational Exchange is protected by some security
MUST be decrypted using the ISAKMP SA. Once the decryption is service (e.g. authentication for an Auth-Only SA, encryption for
other exchanges), the message MUST have these security services
applied using the ISAKMP SA. Once the security service processing is
complete the processing can continue as described below. Any errors complete the processing can continue as described below. Any errors
that occur during the decryption process will be evident when that occur during the security service processing will be evident
checking information in the Delete payload. The local security when checking information in the Delete payload. The local security
policy SHOULD dictate any action to be taken as a result of policy SHOULD dictate any action to be taken as a result of security
decryption errors. service processing errors.
2. Determine if the Domain of Interpretation (DOI) is supported. If the 2. Determine if the Domain of Interpretation (DOI) is supported. If the
DOI determination fails, the message is discarded and the following DOI determination fails, the payload is discarded and the following
action is taken: action is taken:
(a) The event, INVALID DOI, is logged in the appropriate system audit (a) The event, INVALID DOI, MAY be logged in the appropriate system
file. audit file.
3. Determine if the Protocol-Id is supported. If the Protocol-Id 3. Determine if the Protocol-Id is supported. If the Protocol-Id
determination fails, the message is discarded and the following determination fails, the payload is discarded and the following
action is taken: action is taken:
(a) The event, INVALID PROTOCOL-ID, is logged in the appropriate (a) The event, INVALID PROTOCOL-ID, MAY be logged in the appropriate
system audit file. system audit file.
4. Determine if the SPI is valid for each SPI included in the Delete 4. Determine if the SPI is valid for each SPI included in the Delete
payload. For each SPI that is invalid, the following action is payload. For each SPI that is invalid, the following action is
taken: taken:
(a) The event, INVALID SPI, is logged in the appropriate system audit (a) The event, INVALID SPI, MAY be logged in the appropriate system
file. audit file.
5. Process the Delete payload and take appropriate action, according to 5. Process the Delete payload and take appropriate action, according to
local security policy. As described above, one appropriate action local security policy. As described above, one appropriate action
SHOULD include cleaning up the local SA database. SHOULD include cleaning up the local SA database.
6 Conclusions 6 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 mas- a well designed protocol aimed at the Internet of the future. The mas-
sive growth of the Internet will lead to great diversity in network uti- sive growth of the Internet will lead to great diversity in network uti-
skipping to change at page 74, line 19 skipping to change at page 76, line 19
As detailed in previous sections, ISAKMP is designed to provide a flexible As detailed in previous sections, ISAKMP is designed to provide a flexible
and extensible framework for establishing and managing Security Associa- and extensible framework for establishing and managing Security Associa-
tions and cryptographic keys. The framework provided by ISAKMP consists tions and cryptographic keys. The framework provided by ISAKMP consists
of header and payload definitions, exchange types for guiding message and of header and payload definitions, exchange types for guiding message and
payload exchanges, and general processing guidelines. ISAKMP does not payload exchanges, and general processing guidelines. ISAKMP does not
define the mechanisms that will be used to establish and manage Security define the mechanisms that will be used to establish and manage Security
Associations and cryptographic keys in an authenticated and confidential Associations and cryptographic keys in an authenticated and confidential
manner. The definition of mechanisms and their application is the purview manner. The definition of mechanisms and their application is the purview
of individual Domains of Interpretation (DOIs). of individual Domains of Interpretation (DOIs).
This section describes the ISAKMP values for the Internet IP Security DOI. This section describes the ISAKMP values for the Internet IP Security DOI,
The Internet IP Security DOI is MANDATORY to implement for IP Security. supported security protocols, and identification values for ISAKMP Phase 1
[Oakley] and [IO-Res] describe, in detail, the mechanisms and their ap- negotiations. The Internet IP Security DOI is MANDATORY to implement for
plication for establishing and managing Security Associations and crypto- IP Security. [Oakley] and [IKE] describe, in detail, the mechanisms and
graphic keys for IP Security. their application for establishing and managing Security Associations and
cryptographic keys for IP Security.
A.2 Assigned Values for the Internet IP Security DOI
A.2.1 Internet IP Security DOI Assigned Value A.2 Internet IP Security DOI Assigned Value
As described in [IPDOI], the Internet IP Security DOI Assigned Number is As described in [IPDOI], the Internet IP Security DOI Assigned Number is
one (1). one (1).
A.2.2 Supported Security Protocols A.3 Supported Security Protocols
Values for supported security protocols are specified in the most recent Values for supported security protocols are specified in the most recent
``Assigned Numbers'' RFC [STD-2]. Presented in the following table are ``Assigned Numbers'' RFC [STD-2]. Presented in the following table are
the values for the security protocols supported by ISAKMP for the Internet the values for the security protocols supported by ISAKMP for the Internet
IP Security DOI. IP Security DOI.
_Protocol_Assigned_Value__ _Protocol_Assigned_Value__
RESERVED 0 RESERVED 0
ISAKMP 1 ISAKMP 1
All DOIs MUST reserve ISAKMP with a Protocol-ID of 1. All other security All DOIs MUST reserve ISAKMP with a Protocol-ID of 1. All other security
protocols within that DOI will be numbered accordingly. protocols within that DOI will be numbered accordingly.
Security protocol values 2-1023 are reserved for IANA use. Values 1024- Security protocol values 2-15359 are reserved to IANA for future use.
15359 are reserved for future use. Values 15360-16383 are reserved for Values 15360-16383 are permanently reserved for private use amongst mu-
private use. tually consenting implementations. Such private use values are unlikely
to be interoperable across different implementations.
A.4 ISAKMP Identification Type Values
The following table lists the assigned values for the Identification Type
field found in the Identification payload during a generic Phase 1 ex-
change, which is not for a specific protocol.
______ID_Type_______Value_
ID_IPV4_ADDR 0
ID_IPV4_ADDR_SUBNET 1
ID_IPV6_ADDR 2
ID_IPV6_ADDR_SUBNET 3
A.4.1 ID_IPV4_ADDR
The ID_IPV4_ADDR type specifies a single four (4) octet IPv4 address.
A.4.2 ID_IPV4_ADDR_SUBNET
The ID_IPV4_ADDR_SUBNET type specifies a range of IPv4 addresses, repre-
sented by two four (4) octet values. The first value is an IPv4 address.
The second is an IPv4 network mask. Note that ones (1s) in the network
mask indicate that the corresponding bit in the address is fixed, while
zeros (0s) indicate a "wildcard" bit.
A.4.3 ID_IPV6_ADDR
The ID_IPV6_ADDR type specifies a single sixteen (16) octet IPv6 address.
A.4.4 ID_IPV6_ADDR_SUBNET
The ID_IPV6_ADDR_SUBNET type specifies a range of IPv6 addresses, repre-
sented by two sixteen (16) octet values. The first value is an IPv6 ad-
dress. The second is an IPv6 network mask. Note that ones (1s) in the
network mask indicate that the corresponding bit in the address is fixed,
while zeros (0s) indicate a "wildcard" bit.
B Defining a new Domain of Interpretation B Defining a new Domain of Interpretation
The Internet DOI may be sufficient to meet the security requirements of The Internet DOI may be sufficient to meet the security requirements of
a large portion of the internet community. However, some groups may have a large portion of the internet community. However, some groups may have
a need to customize some aspect of a DOI, perhaps to add a different set a need to customize some aspect of a DOI, perhaps to add a different set
of cryptographic algorithms, or perhaps because they want to make their of cryptographic algorithms, or perhaps because they want to make their
security-relevant decisions based on something other than a host id or security-relevant decisions based on something other than a host id or
user id. Also, a particular group may have a need for a new exchange user id. Also, a particular group may have a need for a new exchange
type, for example to support key management for multicast groups. type, for example to support key management for multicast groups.
skipping to change at page 79, line 36 skipping to change at page 81, line 36
Another issue that must be considered in the development of ISAKMP is the Another issue that must be considered in the development of ISAKMP is the
effect of firewalls on the protocol. Many firewalls filter out all UDP effect of firewalls on the protocol. Many firewalls filter out all UDP
packets, making reliance on UDP questionable in certain environments. packets, making reliance on UDP questionable in certain environments.
A number of very important security considerations are presented in A number of very important security considerations are presented in
[RFC-1825]. One bears repeating. Once a private session key is created, [RFC-1825]. One bears 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 protection provided by the IP Security services. any protection provided by the IP Security services.
IANA Considerations
This document contains many "magic" numbers to be maintained by the IANA.
This section explains the criteria to be used by the IANA to assign addi-
tional numbers in each of these lists.
Domain of Interpretation
The Domain of Interpretation (DOI) is a 32-bit field which identifies the
domain under which the security association negotiation is taking place.
Requests for assignments of new DOIs must be accompanied by a standards-
track RFC which describes the specific domain.
Supported Security Protocols
ISAKMP is designed to provide security association negotiation and key
management for many security protocols. Requests for identifiers for ad-
ditional security protocols must be accompanied by a standards-track RFC
which describes the security protocol and its relationship to ISAKMP.
Acknowledgements Acknowledgements
Dan Harkins, Dave Carrel, and Derrell Piper of Cisco Systems provided de- Dan Harkins, Dave Carrel, and Derrell Piper of Cisco Systems provided
sign assistance with the protocol and coordination for the [IO-Res] and design assistance with the protocol and coordination for the [IKE] and
[IPDOI] documents. [IPDOI] documents.
Hilarie Orman, via the Oakley key exchange protocol, has significantly Hilarie Orman, via the Oakley key exchange protocol, has significantly
influenced the design of ISAKMP. influenced the design of ISAKMP.
Marsha Gross, Bill Kutz, Mike Oehler, Pete Sell, and Ruth Taylor provided Marsha Gross, Bill Kutz, Mike Oehler, Pete Sell, and Ruth Taylor provided
significant input and review to this document. significant input and review to this document.
Scott Carlson ported the TIS DNSSEC prototype to FreeBSD for use with the Scott Carlson ported the TIS DNSSEC prototype to FreeBSD for use with the
ISAKMP prototype. ISAKMP prototype.
skipping to change at page 81, line 11 skipping to change at page 83, line 11
ISAKMP implementors. ISAKMP implementors.
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
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Industry -- Establishment of Symmetric Algorithm Keys Using Industry -- Establishment of Symmetric Algorithm Keys Using
Diffie-Hellman, Working Draft, April 19, 1996. Diffie-Hellman, Working Draft, April 19, 1996.
[RFC-1825] Randall Atkinson, Security Architecture for the Internet
Protocol, RFC-1825, August, 1995.
[BC] Ballardie, A. and J. Crowcroft, Multicast-specific Security Threats [BC] Ballardie, A. and J. Crowcroft, Multicast-specific Security Threats
and Countermeasures, Proceedings of 1995 ISOC Symposium on Networks and Countermeasures, Proceedings of 1995 ISOC Symposium on Networks
& Distributed Systems Security, pp. 17-30, Internet Society, San & Distributed Systems Security, pp. 17-30, Internet Society, San
Diego, CA, February 1995. Diego, CA, February 1995.
[RFC-1949] A. Ballardie, Scalable Multicast Key Distribution, RFC-1949,
May, 1996.
[Berge] Berge, N.H., UNINETT PCA Policy Statements, Internet-Draft, work [Berge] Berge, N.H., UNINETT PCA Policy Statements, Internet-Draft, work
in progress, November, 1995. in progress, November, 1995.
[CW87] Clark, D.D. and D.R. Wilson, A Comparison of Commercial and [CW87] Clark, D.D. and D.R. Wilson, A Comparison of Commercial and
Military Computer Security Policies, Proceedings of the IEEE Military Computer Security Policies, Proceedings of the IEEE
Symposium on Security & Privacy, Oakland, CA, 1987, pp 184-193. Symposium on Security & Privacy, Oakland, CA, 1987, pp. 184-193.
[DNSSEC] D. Eastlake III, Domain Name System Protocol Security
Extensions, Internet-Draft: draft-ietf-dnssec-secext2-03.txt, Work
in Progress, January 1998.
[DOW92] Diffie, W., M.Wiener, P. Van Oorschot, Authentication and [DOW92] Diffie, W., 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.
[DNSSEC] D. Eastlake III, Domain Name System Protocol Security [IAB] Bellovin, S., Report of the IAB Security Architecture Workshop,
Extensions, Internet-Draft: draft-ietf-dnssec-secext2-00.txt, Work Internet-Draft: draft-iab-secwks-report-00.txt, Work in Progress,
in Progress, July 1997. November 1997.
[Karn] Karn, P. and B. Simpson, The Photuris Session Key Management [IKE] Harkins, D. and D. Carrel, The Internet Key Exchange (IKE),
Internet-Draft: draft-ietf-ipsec-isakmp-oakley-06.txt, Work in
Progress, February 1998.
[IPDOI] Derrell Piper, The Internet IP Security Domain of Interpretation
for ISAKMP, Internet-Draft: draft-ietf-ipsec-ipsec-doi-07.txt, Work
in Progress, February 1998.
[Karn] Karn, P. and B. Simpson, Photuris: Session Key Management
Protocol, Internet-Draft: draft-simpson-photuris-15.txt, Work in Protocol, Internet-Draft: draft-simpson-photuris-15.txt, Work in
Progress, July 1997. Progress, July 1997.
[RFC-1422] Steve Kent, Privacy Enhancement for Internet Electronic Mail:
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.
[Oakley] H. K. Orman, The Oakley Key Determination Protocol, Internet- [Oakley] H. K. Orman, The Oakley Key Determination Protocol, Internet-
Draft: draft-ietf-ipsec-oakley-02.txt, Work in Progress, July 1997. Draft: draft-ietf-ipsec-oakley-02.txt, Work in Progress, July 1997.
[IO-Res] Harkins, D. and D. Carrel, The Resolution of ISAKMP with Oakley, [RFC-1422] Steve Kent, Privacy Enhancement for Internet Electronic Mail:
Internet-Draft: draft-ietf-ipsec-isakmp-oakley-04.txt, Work in Part II: Certificate-Based Key Management, RFC-1422, February 1993.
Progress, July 1997.
[IPDOI] Derrell Piper, The Internet IP Security Domain of Interpretation [RFC-1825] Randall Atkinson, Security Architecture for the Internet
for ISAKMP, Internet-Draft: draft-ietf-ipsec-ipsec-doi-03.txt, Work Protocol, RFC-1825, August, 1995.
in Progress, July 1997.
[STD-2] Reynolds, J. and J. Postel, Assigned Numbers, STD 2, October, [RFC-1949] A. Ballardie, Scalable Multicast Key Distribution, RFC-1949,
1994. May 1996.
[Schneier] Bruce Schneier, Applied Cryptography - Protocols, Algorithms, [RFC-2093] Harney, H. and C. Muckenhirn, Group Key Management Protocol
and Source Code in C (Second Edition), John Wiley & Sons, Inc., (GKMP) Specification, SPARTA, Inc., RFC-2093, July 1997.
1996.
[RFC-2094] Harney, H. and C. Muckenhirn, Group Key Management Protocol [RFC-2094] Harney, H. and C. Muckenhirn, Group Key Management Protocol
(GKMP) Architecture, SPARTA, Inc., RFC-2094, July 1997. (GKMP) Architecture, SPARTA, Inc., RFC-2094, July 1997.
[RFC-2093] Harney, H. and C. Muckenhirn, Group Key Management Protocol [RFC-2119] S. Bradner, Key Words for use in RFCs to Indicate Requirement
(GKMP) Specification, SPARTA, Inc., RFC-2093, July 1997. Levels, Harvard University, RFC-2119, March 1997.
[Schneier] Bruce Schneier, Applied Cryptography - Protocols, Algorithms,
and Source Code in C (Second Edition), John Wiley & Sons, Inc.,
1996.
[STD-2] Reynolds, J. and J. Postel, Assigned Numbers, STD 2, October,
1994.
Addresses of Authors Addresses of Authors
The authors can be contacted at: The authors can be contacted at:
Douglas Maughan Douglas Maughan
Phone: 301-688-0847 Phone: 301-688-0847
E-mail:wdmaugh@tycho.ncsc.mil E-mail:wdm@tycho.ncsc.mil
Mark Schneider Mark Schneider
Phone: 301-688-0851 Phone: 301-688-0851
E-mail:mss@tycho.ncsc.mil E-mail:mss@tycho.ncsc.mil
Jeff Turner
Phone: 301-688-0849
E-mail:sjt@epoch.ncsc.mil
National Security Agency National Security Agency
ATTN: R23 ATTN: R23
9800 Savage Road 9800 Savage Road
Ft. Meade, MD. 20755-6000 Ft. Meade, MD. 20755-6000
Mark Schertler Mark Schertler
Terisa Systems, Inc. Terisa Systems, Inc.
4984 El Camino Real 4984 El Camino Real
Los Altos, CA. 94022 Los Altos, CA. 94022
Phone: 415-919-1773 Phone: 650-919-1773
E-mail:mjs@terisa.com E-mail:mjs@terisa.com
Jeff Turner
RABA Technologies, Inc.
10500 Little Patuxent Parkway
Columbia, MD. 21044
Phone: 410-715-9399
E-mail:jeff.turner@raba.com
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