< draft-ietf-ipsec-ikev2-11.txt   draft-ietf-ipsec-ikev2-12.txt >
INTERNET-DRAFT Charlie Kaufman, Editor INTERNET-DRAFT Charlie Kaufman, Editor
draft-ietf-ipsec-ikev2-11.txt draft-ietf-ipsec-ikev2-12.txt
Obsoletes: 2407, 2408, 2409 October 9, 2003 Obsoletes: 2407, 2408, 2409 January 6, 2004
Expires: April 2004 Expires: July 2004
Internet Key Exchange (IKEv2) Protocol Internet Key Exchange (IKEv2) Protocol
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026. Internet-Drafts are working documents of of Section 10 of RFC2026. Internet-Drafts are working documents of
the Internet Engineering Task Force (IETF), its areas, and its the Internet Engineering Task Force (IETF), its areas, and its
working groups. Note that other groups may also distribute working working groups. Note that other groups may also distribute working
documents as Internet-Drafts. documents as Internet-Drafts.
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The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
This document is a submission by the IPSEC Working Group of the This document is a submission by the IPSEC Working Group of the
Internet Engineering Task Force (IETF). Comments should be submitted Internet Engineering Task Force (IETF). Comments should be submitted
to the ipsec@lists.tislabs.com mailing list. to the ipsec@lists.tislabs.com mailing list.
Distribution of this memo is unlimited. Distribution of this memo is unlimited.
This Internet-Draft expires in April 2004. This Internet-Draft expires in July 2004.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract Abstract
This document describes version 2 of the Internet Key Exchange (IKE) This document describes version 2 of the Internet Key Exchange (IKE)
protocol. IKE is a component of IPsec used for performing mutual protocol. IKE is a component of IPsec used for performing mutual
authentication and establishing and maintaining security authentication and establishing and maintaining security
associations. associations.
This version of the IKE specification combines the contents of what This version of the IKE specification combines the contents of what
were previously separate documents, including ISAKMP (RFC 2408), IKE were previously separate documents, including ISAKMP (RFC 2408), IKE
(RFC 2409), the Internet DOI (RFC 2407), NAT Traversal, Legacy (RFC 2409), the Internet DOI (RFC 2407), NAT Traversal, Legacy
authentication, and remote address acquisition. authentication, and remote address acquisition.
Version 2 of IKE does not interoperate with version 1, but it has Version 2 of IKE does not interoperate with version 1, but it has
enough of the header format in common that both versions can enough of the header format in common that both versions can
unambiguously run over the same UDP port. unambiguously run over the same UDP port.
Table of Contents Table of Contents
1 Introduction 1 Introduction...............................................3
1.1 Usage Scenarios 1.1 Usage Scenarios..........................................5
1.2 The Initial Exchange 1.2 The Initial Exchange.....................................7
1.3 The CREATE_CHILD_SA Exchange 1.3 The CREATE_CHILD_SA Exchange.............................9
1.4 The INFORMATIONAL Exchange 1.4 The INFORMATIONAL Exchange..............................10
1.5 Informational Messages outside of an IKE_SA 1.5 Informational Messages outside of an IKE_SA.............12
2 IKE Protocol Details and Variations 2 IKE Protocol Details and Variations.......................12
2.1 Use of Retransmission Timers 2.1 Use of Retransmission Timers............................12
2.2 Use of Sequence Numbers for Message ID 2.2 Use of Sequence Numbers for Message ID..................13
2.3 Window Size for overlapping requests 2.3 Window Size for overlapping requests....................13
2.4 State Synchronization and Connection Timeouts 2.4 State Synchronization and Connection Timeouts...........14
2.5 Version Numbers and Forward Compatibility 2.5 Version Numbers and Forward Compatibility...............16
2.6 Cookies 2.6 Cookies.................................................17
2.7 Cryptographic Algorithm Negotiation 2.7 Cryptographic Algorithm Negotiation.....................19
2.8 Rekeying 2.8 Rekeying................................................20
2.9 Traffic Selector Negotiation 2.9 Traffic Selector Negotiation............................22
2.10 Nonces 2.10 Nonces.................................................24
2.11 Address and Port Agility 2.11 Address and Port Agility...............................25
2.12 Reuse of Diffie-Hellman Exponentials 2.12 Reuse of Diffie-Hellman Exponentials...................25
2.13 Generating Keying Material 2.13 Generating Keying Material.............................26
2.14 Generating Keying Material for the IKE_SA 2.14 Generating Keying Material for the IKE_SA..............27
2.15 Authentication of the IKE_SA 2.15 Authentication of the IKE_SA...........................28
2.16 Extended Authentication Protocol Methods 2.16 Extended Authentication Protocol Methods...............29
2.17 Generating Keying Material for CHILD_SAs 2.17 Generating Keying Material for CHILD_SAs...............31
2.18 Rekeying IKE_SAs using a CREATE_CHILD_SA exchange 2.18 Rekeying IKE_SAs using a CREATE_CHILD_SA exchange......32
2.19 Requesting an internal address on a remote network 2.19 Requesting an internal address on a remote network.....32
2.20 Requesting a Peer's Version 2.20 Requesting a Peer's Version............................33
2.21 Error Handling 2.21 Error Handling.........................................34
2.22 IPComp 2.22 IPComp.................................................35
2.23 NAT Traversal 2.23 NAT Traversal..........................................36
2.24 ECN (Explicit Congestion Notification) 2.24 ECN (Explicit Congestion Notification).................38
3 Header and Payload Formats 3 Header and Payload Formats................................39
3.1 The IKE Header 3.1 The IKE Header..........................................39
3.2 Generic Payload Header 3.2 Generic Payload Header..................................42
3.3 Security Association Payload 3.3 Security Association Payload............................43
3.4 Key Exchange Payload 3.4 Key Exchange Payload....................................53
3.5 Identification Payloads 3.5 Identification Payloads.................................54
3.6 Certificate Payload 3.6 Certificate Payload.....................................56
3.7 Certificate Request Payload 3.7 Certificate Request Payload.............................58
3.8 Authentication Payload 3.8 Authentication Payload..................................60
3.9 Nonce Payload 3.9 Nonce Payload...........................................61
3.10 Notify Payload 3.10 Notify Payload.........................................61
3.11 Delete Payload 3.11 Delete Payload.........................................68
3.12 Vendor ID Payload 3.12 Vendor ID Payload......................................70
3.13 Traffic Selector Payload 3.13 Traffic Selector Payload...............................71
3.14 Encrypted Payload 3.14 Encrypted Payload......................................73
3.15 Configuration Payload 3.15 Configuration Payload..................................75
3.16 Extended Authentication Protocol (EAP) Payload 3.16 Extended Authentication Protocol (EAP) Payload.........80
4 Conformance Requirements 4 Conformance Requirements..................................82
5 Security Considerations 5 Security Considerations...................................84
6 IANA Considerations 6 IANA Considerations.......................................86
7 Intellectual property rights 7 Intellectual property rights..............................86
8 Acknowledgements 8 Acknowledgements..........................................86
9 References 9 References................................................87
9.1 Normative References 9.1 Normative References....................................87
9.2 Informative References 9.2 Informative References..................................88
Appendix A: Summary of Changes from IKEv1 Appendix A: Summary of Changes from IKEv1...................91
Appendix B: Diffie-Hellman Groups Appendix B: Diffie-Hellman Groups...........................93
Change History (To be removed from RFC) Change History (To be removed from RFC).....................95
Editor's Address Editor's Address...........................................102
Full Copyright Statement Full Copyright Statement...................................102
Requirements Terminology Requirements Terminology
Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT" and Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT" and
"MAY" that appear in this document are to be interpreted as described "MAY" that appear in this document are to be interpreted as described
in [Bra97]. in [Bra97].
1 Introduction 1 Introduction
IP Security (IPsec) provides confidentiality, data integrity, access IP Security (IPsec) provides confidentiality, data integrity, access
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well. Therefore a protocol to establish this state dynamically is well. Therefore a protocol to establish this state dynamically is
needed. This memo describes such a protocol-- the Internet Key needed. This memo describes such a protocol-- the Internet Key
Exchange (IKE). This is version 2 of IKE. Version 1 of IKE was Exchange (IKE). This is version 2 of IKE. Version 1 of IKE was
defined in RFCs 2407, 2408, and 2409. This single document is defined in RFCs 2407, 2408, and 2409. This single document is
intended to replace all three of those RFCs. intended to replace all three of those RFCs.
IKE performs mutual authentication between two parties and IKE performs mutual authentication between two parties and
establishes an IKE security association that includes shared secret establishes an IKE security association that includes shared secret
information that can be used to efficiently establish SAs for ESP information that can be used to efficiently establish SAs for ESP
[RFC2406] and/or AH [RFC2402] and a set of cryptographic algorithms [RFC2406] and/or AH [RFC2402] and a set of cryptographic algorithms
to be used to protect the SAs. In this document, the term "suite" or to be used by the SAs to protect the traffic that they carry. In
"cryptographic suite" refers to a complete set of algorithms used to this document, the term "suite" or "cryptographic suite" refers to a
protect an SA. An initiator proposes one or more suites by listing complete set of algorithms used to protect an SA. An initiator
supported algorithms that can be combined into suites in a mix and proposes one or more suites by listing supported algorithms that can
match fashion. IKE can also negotiate use of IPComp [IPCOMP] in be combined into suites in a mix and match fashion. IKE can also
connection with an ESP and/or AH SA. We call the IKE SA an "IKE_SA". negotiate use of IPComp [IPCOMP] in connection with an ESP and/or AH
The SAs for ESP and/or AH that get set up through that IKE_SA we call SA. We call the IKE SA an "IKE_SA". The SAs for ESP and/or AH that
"CHILD_SA"s. get set up through that IKE_SA we call "CHILD_SA"s.
All IKE communications consist of pairs of messages: a request and a All IKE communications consist of pairs of messages: a request and a
response. The pair is called an "exchange". We call the first response. The pair is called an "exchange". We call the first
messages establishing an IKE_SA IKE_SA_INIT and IKE_AUTH exchanges messages establishing an IKE_SA IKE_SA_INIT and IKE_AUTH exchanges
and subsequent IKE exchanges CREATE_CHILD_SA or INFORMATIONAL and subsequent IKE exchanges CREATE_CHILD_SA or INFORMATIONAL
exchanges. In the common case, there is a single IKE_SA_INIT exchange exchanges. In the common case, there is a single IKE_SA_INIT exchange
and a single IKE_AUTH exchange (a total of four messages) to and a single IKE_AUTH exchange (a total of four messages) to
establish the IKE_SA and the first CHILD_SA. In exceptional cases, establish the IKE_SA and the first CHILD_SA. In exceptional cases,
there may be more than one of each of these exchanges. In all cases, there may be more than one of each of these exchanges. In all cases,
all IKE_SA_INIT exchanges MUST complete before any other exchange all IKE_SA_INIT exchanges MUST complete before any other exchange
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Protected !Tunnel ! Tunnel !Tunnel ! Protected Protected !Tunnel ! Tunnel !Tunnel ! Protected
Subnet <-->!Endpoint !<---------->!Endpoint !<--> Subnet Subnet <-->!Endpoint !<---------->!Endpoint !<--> Subnet
! ! ! ! ! ! ! !
+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+
Figure 1: Security Gateway to Security Gateway Tunnel Figure 1: Security Gateway to Security Gateway Tunnel
In this scenario, neither endpoint of the IP connection implements In this scenario, neither endpoint of the IP connection implements
IPsec, but network nodes between them protect traffic for part of the IPsec, but network nodes between them protect traffic for part of the
way. Protection is transparent to the endpoints, and depends on way. Protection is transparent to the endpoints, and depends on
ordinary routing sending packets through the tunnel endpoints for ordinary routing to send packets through the tunnel endpoints for
processing. Each endpoint would announce the set of addresses processing. Each endpoint would announce the set of addresses
"behind" it, and packets would be sent in Tunnel Mode where the inner "behind" it, and packets would be sent in Tunnel Mode where the inner
IP header would contain the IP addresses of the actual endpoints. IP header would contain the IP addresses of the actual endpoints.
1.1.2 Endpoint to Endpoint Transport 1.1.2 Endpoint to Endpoint Transport
+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+
! ! IPsec ! ! ! ! IPsec ! !
!Protected! Tunnel !Protected! !Protected! Tunnel !Protected!
!Endpoint !<---------------------------------------->!Endpoint ! !Endpoint !<---------------------------------------->!Endpoint !
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+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+
Figure 2: Endpoint to Endpoint Figure 2: Endpoint to Endpoint
In this scenario, both endpoints of the IP connection implement In this scenario, both endpoints of the IP connection implement
IPsec. These endpoints may implement application layer access IPsec. These endpoints may implement application layer access
controls based on the authenticated identities of the participants. controls based on the authenticated identities of the participants.
Transport mode will commonly be used with no inner IP header. If Transport mode will commonly be used with no inner IP header. If
there is an inner IP header, the inner addresses will be the same as there is an inner IP header, the inner addresses will be the same as
the outer addresses. A single pair of addresses will be negotiated the outer addresses. A single pair of addresses will be negotiated
for packets to be sent over this SA. for packets to be protected by this SA.
It is possible in this scenario that one or both of the protected It is possible in this scenario that one or both of the protected
endpoints will be behind a network address translation (NAT) node, in endpoints will be behind a network address translation (NAT) node, in
which case the tunnelled packets will have to be UDP encapsulated so which case the tunnelled packets will have to be UDP encapsulated so
that port numbers in the UDP headers can be used to identify that port numbers in the UDP headers can be used to identify
individual endpoints "behind" the NAT. individual endpoints "behind" the NAT (see section 2.23).
1.1.3 Endpoint to Security Gateway Transport 1.1.3 Endpoint to Security Gateway Transport
+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+
! ! IPsec ! ! Protected ! ! IPsec ! ! Protected
!Protected! Tunnel !Tunnel ! Subnet !Protected! Tunnel !Tunnel ! Subnet
!Endpoint !<------------------------>!Endpoint !<--- and/or !Endpoint !<------------------------>!Endpoint !<--- and/or
! ! ! ! Internet ! ! ! ! Internet
+-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+ +-+-+-+-+-+
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protected with keys established through the IKE_SA_INIT exchange, so protected with keys established through the IKE_SA_INIT exchange, so
the identities are hidden from eavesdroppers and all fields in all the identities are hidden from eavesdroppers and all fields in all
the messages are authenticated. the messages are authenticated.
In the following description, the payloads contained in the message In the following description, the payloads contained in the message
are indicated by names such as SA. The details of the contents of are indicated by names such as SA. The details of the contents of
each payload are described later. Payloads which may optionally each payload are described later. Payloads which may optionally
appear will be shown in brackets, such as [CERTREQ], would indicate appear will be shown in brackets, such as [CERTREQ], would indicate
that optionally a certificate request payload can be included. that optionally a certificate request payload can be included.
To simplify the descriptions that follow by allowing the use of
gender specific personal pronouns, the initiator is assumed to be
named "Alice" and the responder "Bob".
The initial exchanges are as follows: The initial exchanges are as follows:
Initiator Responder Initiator Responder
----------- ----------- ----------- -----------
HDR, SAi1, KEi, Ni --> HDR, SAi1, KEi, Ni -->
HDR contains the SPIs, version numbers, and flags of various sorts. HDR contains the SPIs, version numbers, and flags of various sorts.
The SAi1 payload states the cryptographic algorithms the Initiator The SAi1 payload states the cryptographic algorithms the Initiator
supports for the IKE_SA. The KE payload sends the Initiator's supports for the IKE_SA. The KE payload sends the Initiator's
Diffie-Hellman value. Ni is the Initiator's nonce. Diffie-Hellman value. Ni is the Initiator's nonce.
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another quantity SK_d is derived and used for derivation of further another quantity SK_d is derived and used for derivation of further
keying material for CHILD_SAs. The notation SK { ... } indicates keying material for CHILD_SAs. The notation SK { ... } indicates
that these payloads are encrypted and integrity protected using that that these payloads are encrypted and integrity protected using that
direction's SK_e and SK_a. direction's SK_e and SK_a.
HDR, SK {IDi, [CERT,] [CERTREQ,] [IDr,] HDR, SK {IDi, [CERT,] [CERTREQ,] [IDr,]
AUTH, SAi2, TSi, TSr} --> AUTH, SAi2, TSi, TSr} -->
The Initiator asserts her identity with the IDi payload, proves The Initiator asserts her identity with the IDi payload, proves
knowledge of the secret corresponding to IDi and integrity protects knowledge of the secret corresponding to IDi and integrity protects
the contents of the first two messages using the AUTH payload (see the contents of the first message using the AUTH payload (see section
section 2.15). She might also send her certificate(s) in CERT 2.15). She might also send her certificate(s) in CERT payload(s) and
payload(s) and a list of her trust anchors in CERTREQ payload(s). If a list of her trust anchors in CERTREQ payload(s). If any CERT
any CERT payloads are included, the first certificate provided MUST payloads are included, the first certificate provided MUST contain
contain the public key used to verify the AUTH field. The optional the public key used to verify the AUTH field. The optional payload
payload IDr enables Alice to specify which of Bob's identities she IDr enables Alice to specify which of Bob's identities she wants to
wants to talk to. This is useful when Bob is hosting multiple talk to. This is useful when Bob is hosting multiple identities at
identities at the same IP address. She begins negotiation of a the same IP address. She begins negotiation of a CHILD_SA using the
CHILD_SA using the SAi2 payload. The final fields (starting with SAi2 payload. The final fields (starting with SAi2) are described in
SAi2) are described in the description of the CREATE_CHILD_SA the description of the CREATE_CHILD_SA exchange.
exchange.
<-- HDR, SK {IDr, [CERT,] AUTH, <-- HDR, SK {IDr, [CERT,] AUTH,
SAr2, TSi, TSr} SAr2, TSi, TSr}
The Responder asserts his identity with the IDr payload, optionally The Responder asserts his identity with the IDr payload, optionally
sends one or more certificates (again with the certificate containing sends one or more certificates (again with the certificate containing
the public key used to verify AUTH listed first), authenticates his the public key used to verify AUTH listed first), authenticates his
identity with the AUTH payload, and completes negotiation of a identity and protects the integrity of the second message with the
CHILD_SA with the additional fields described below in the AUTH payload, and completes negotiation of a CHILD_SA with the
CREATE_CHILD_SA exchange. additional fields described below in the CREATE_CHILD_SA exchange.
The recipients of messages 3 and 4 MUST verify that all signatures The recipients of messages 3 and 4 MUST verify that all signatures
and MACs are computed correctly and that the names in the ID payloads and MACs are computed correctly and that the names in the ID payloads
correspond to the keys used to generate the AUTH payload. correspond to the keys used to generate the AUTH payload.
1.3 The CREATE_CHILD_SA Exchange 1.3 The CREATE_CHILD_SA Exchange
This exchange consists of a single request/response pair, and was This exchange consists of a single request/response pair, and was
referred to as a phase 2 exchange in IKEv1. It MAY be initiated by referred to as a phase 2 exchange in IKEv1. It MAY be initiated by
either end of the IKE_SA after the initial exchanges are completed. either end of the IKE_SA after the initial exchanges are completed.
All messages following the initial exchange are cryptographically All messages following the initial exchange are cryptographically
protected using the cryptographic algorithms and keys negotiated in protected using the cryptographic algorithms and keys negotiated in
the first two messages of the IKE exchange using a syntax described the first two messages of the IKE exchange. These subsequent
in section 3.14. messages use the syntax of the Encrypted Payload described in section
3.14.
Either endpoint may initiate a CREATE_CHILD_SA exchange, so in this Either endpoint may initiate a CREATE_CHILD_SA exchange, so in this
section the term Initiator refers to the endpoint initiating this section the term initiator refers to the endpoint initiating this
exchange. exchange. The term "Alice" will always refer to the initiator of the
outer IKE_SA.
A CHILD_SA is created by sending a CREATE_CHILD_SA request. The A CHILD_SA is created by sending a CREATE_CHILD_SA request. The
CREATE_CHILD_SA request MAY optionally contain a KE payload for an CREATE_CHILD_SA request MAY optionally contain a KE payload for an
additional Diffie-Hellman exchange to enable stronger guarantees of additional Diffie-Hellman exchange to enable stronger guarantees of
forward secrecy for the CHILD_SA. The keying material for the forward secrecy for the CHILD_SA. The keying material for the
CHILD_SA is a function of SK_d established during the establishment CHILD_SA is a function of SK_d established during the establishment
of the IKE_SA, the nonces exchanged during the CREATE_CHILD_SA of the IKE_SA, the nonces exchanged during the CREATE_CHILD_SA
exchange, and the Diffie-Hellman value (if KE payloads are included exchange, and the Diffie-Hellman value (if KE payloads are included
in the CREATE_CHILD_SA exchange). in the CREATE_CHILD_SA exchange).
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payload and nonce MUST NOT be sent. The nonces from the initial payload and nonce MUST NOT be sent. The nonces from the initial
exchange are used in computing the keys for the CHILD_SA. exchange are used in computing the keys for the CHILD_SA.
The CREATE_CHILD_SA request contains: The CREATE_CHILD_SA request contains:
Initiator Responder Initiator Responder
----------- ----------- ----------- -----------
HDR, SK {[N], SA, Ni, [KEi], HDR, SK {[N], SA, Ni, [KEi],
[TSi, TSr]} --> [TSi, TSr]} -->
The Initiator sends SA offer(s) in the SA payload, a nonce in the Ni The initiator sends SA offer(s) in the SA payload, a nonce in the Ni
payload, optionally a Diffie-Hellman value in the KEi payload, and payload, optionally a Diffie-Hellman value in the KEi payload, and
the proposed traffic selectors in the TSi and TSr payloads. If this the proposed traffic selectors in the TSi and TSr payloads. If this
CREATE_CHILD_SA exchange is rekeying an existing SA other than the CREATE_CHILD_SA exchange is rekeying an existing SA other than the
IKE_SA, the leading N payload of type REKEY_SA MUST identify the SA IKE_SA, the leading N payload of type REKEY_SA MUST identify the SA
being rekeyed. If this CREATE_CHILD_SA exchange is not rekeying and being rekeyed. If this CREATE_CHILD_SA exchange is not rekeying and
existing SA, the N payload MUST be omitted. If the SA offers include existing SA, the N payload MUST be omitted. If the SA offers include
different Diffie-Hellman groups, KEi MUST be an element of the group different Diffie-Hellman groups, KEi MUST be an element of the group
the Initiator expects the responder to accept. If she guesses wrong, the initiator expects the responder to accept. If it guesses wrong,
the CREATE_CHILD_SA exchange will fail and she will have to retry the CREATE_CHILD_SA exchange will fail and it will have to retry with
with a different KEi. a different KEi.
The message following the header is encrypted and the message The message following the header is encrypted and the message
including the header is integrity protected using the cryptographic including the header is integrity protected using the cryptographic
algorithms negotiated for the IKE_SA. algorithms negotiated for the IKE_SA.
The CREATE_CHILD_SA response contains: The CREATE_CHILD_SA response contains:
<-- HDR, SK {SA, Nr, [KEr], <-- HDR, SK {SA, Nr, [KEr],
[TSi, TSr]} [TSi, TSr]}
The Responder replies (using the same Message ID to respond) with the The responder replies (using the same Message ID to respond) with the
accepted offer in an SA payload, and a Diffie-Hellman value in the accepted offer in an SA payload, and a Diffie-Hellman value in the
KEr payload if KEi was included in the request and the selected KEr payload if KEi was included in the request and the selected
cryptographic suite includes that group. If the responder chooses a cryptographic suite includes that group. If the responder chooses a
cryptographic suite with a different group, it MUST reject the cryptographic suite with a different group, it MUST reject the
request. The initiator SHOULD repeat the request, but now with a KEi request. The initiator SHOULD repeat the request, but now with a KEi
payload from the group the responder selected. payload from the group the responder selected.
The traffic selectors for traffic to be sent on that SA are specified The traffic selectors for traffic to be sent on that SA are specified
in the TS payloads, which may be a subset of what the Initiator of in the TS payloads, which may be a subset of what the initiator of
the CHILD_SA proposed. Traffic selectors are omitted if this the CHILD_SA proposed. Traffic selectors are omitted if this
CREATE_CHILD_SA request is being used to change the key of the CREATE_CHILD_SA request is being used to change the key of the
IKE_SA. IKE_SA.
1.4 The INFORMATIONAL Exchange 1.4 The INFORMATIONAL Exchange
At various points during the operation of an IKE_SA, peers may desire At various points during the operation of an IKE_SA, peers may desire
to convey control messages to each other regarding errors or to convey control messages to each other regarding errors or
notifications of certain events. To accomplish this IKE defines an notifications of certain events. To accomplish this IKE defines an
INFORMATIONAL exchange. INFORMATIONAL exchanges MAY ONLY occur after INFORMATIONAL exchange. INFORMATIONAL exchanges MAY ONLY occur after
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supports. If an endpoint supports major version n, and major version supports. If an endpoint supports major version n, and major version
m, it MUST support all versions between n and m. If it receives a m, it MUST support all versions between n and m. If it receives a
message with a major version that it supports, it MUST respond with message with a major version that it supports, it MUST respond with
that version number. In order to prevent two nodes from being tricked that version number. In order to prevent two nodes from being tricked
into corresponding with a lower major version number than the maximum into corresponding with a lower major version number than the maximum
that they both support, IKE has a flag that indicates that the node that they both support, IKE has a flag that indicates that the node
is capable of speaking a higher major version number. is capable of speaking a higher major version number.
Thus the major version number in the IKE header indicates the version Thus the major version number in the IKE header indicates the version
number of the message, not the highest version number that the number of the message, not the highest version number that the
transmitter supports. If A is capable of speaking versions n, n+1, transmitter supports. If Alice is capable of speaking versions n,
and n+2, and B is capable of speaking versions n and n+1, then they n+1, and n+2, and Bob is capable of speaking versions n and n+1, then
will negotiate speaking n+1, where A will set the flag indicating they will negotiate speaking n+1, where Alice will set the flag
ability to speak a higher version. If they mistakenly (perhaps indicating ability to speak a higher version. If they mistakenly
through an active attacker sending error messages) negotiate to (perhaps through an active attacker sending error messages) negotiate
version n, then both will notice that the other side can support a to version n, then both will notice that the other side can support a
higher version number, and they MUST break the connection and higher version number, and they MUST break the connection and
reconnect using version n+1. reconnect using version n+1.
Note that IKEv1 does not follow these rules, because there is no way Note that IKEv1 does not follow these rules, because there is no way
in v1 of noting that you are capable of speaking a higher version in v1 of noting that you are capable of speaking a higher version
number. So an active attacker can trick two v2-capable nodes into number. So an active attacker can trick two v2-capable nodes into
speaking v1. When a v2-capable node negotiates down to v1, it SHOULD speaking v1. When a v2-capable node negotiates down to v1, it SHOULD
note that fact in its logs. note that fact in its logs.
Also for forward compatibility, all fields marked RESERVED MUST be Also for forward compatibility, all fields marked RESERVED MUST be
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While new payload types may be added in the future and may appear While new payload types may be added in the future and may appear
interleaved with the fields defined in this specification, interleaved with the fields defined in this specification,
implementations MUST send the payloads defined in this specification implementations MUST send the payloads defined in this specification
in the order shown in the figures in section 2 and implementations in the order shown in the figures in section 2 and implementations
SHOULD reject as invalid a message with those payloads in any other SHOULD reject as invalid a message with those payloads in any other
order. order.
2.6 Cookies 2.6 Cookies
The term "cookies" originates with Karn and Simpson [RFC 2522] in The term "cookies" originates with Karn and Simpson [RFC 2522] in
Photuris, an early proposal for key management with IPsec. It has Photuris, an early proposal for key management with IPsec, and it has
persisted because the IETF has never rejected a proposal involving persisted. The ISAKMP fixed message header includes two eight octet
cookies. The ISAKMP fixed message header includes two eight octet
fields titled "cookies", and that syntax is used by both IKEv1 and fields titled "cookies", and that syntax is used by both IKEv1 and
IKEv2 though in IKEv2 they are referred to as the IKE SPI and there IKEv2 though in IKEv2 they are referred to as the IKE SPI and there
is a new separate field in a Notify payload holding the cookie. The is a new separate field in a Notify payload holding the cookie. The
initial two eight octet fields in the header are used as a connection initial two eight octet fields in the header are used as a connection
identifier at the beginning of IKE packets. Each endpoint chooses one identifier at the beginning of IKE packets. Each endpoint chooses one
of the two SPIs and SHOULD choose them so as to be unique identifiers of the two SPIs and SHOULD choose them so as to be unique identifiers
of an IKE_SA. An SPI value of zero is special and indicates that the of an IKE_SA. An SPI value of zero is special and indicates that the
remote SPI value is not yet known by the sender. remote SPI value is not yet known by the sender.
Unlike ESP and AH where only the recipient's SPI appears in the Unlike ESP and AH where only the recipient's SPI appears in the
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arrives. The exact algorithms and syntax they use to generate arrives. The exact algorithms and syntax they use to generate
cookies does not affect interoperability and hence is not specified cookies does not affect interoperability and hence is not specified
here. The following is an example of how an endpoint could use here. The following is an example of how an endpoint could use
cookies to implement limited DOS protection. cookies to implement limited DOS protection.
A good way to do this is to set the responder cookie to be: A good way to do this is to set the responder cookie to be:
Cookie = <VersionIDofSecret> | Hash(Ni | IPi | SPIi | <secret>) Cookie = <VersionIDofSecret> | Hash(Ni | IPi | SPIi | <secret>)
where <secret> is a randomly generated secret known only to the where <secret> is a randomly generated secret known only to the
responder and periodically changed. <VersionIDofSecret> should be responder and periodically changed and | indicates concatenation.
changed whenever <secret> is regenerated. The cookie can be <VersionIDofSecret> should be changed whenever <secret> is
recomputed when the IKE_SA_INIT arrives the second time and compared regenerated. The cookie can be recomputed when the IKE_SA_INIT
to the cookie in the received message. If it matches, the responder arrives the second time and compared to the cookie in the received
knows that SPIr was generated since the last change to <secret> and message. If it matches, the responder knows that SPIr was generated
that IPi must be the same as the source address it saw the first since the last change to <secret> and that IPi must be the same as
time. Incorporating SPIi into the calculation assures that if the source address it saw the first time. Incorporating SPIi into the
multiple IKE_SAs are being set up in parallel they will all get calculation assures that if multiple IKE_SAs are being set up in
different cookies (assuming the initiator chooses unique SPIi's). parallel they will all get different cookies (assuming the initiator
Incorporating Ni into the hash assures that an attacker who sees only chooses unique SPIi's). Incorporating Ni into the hash assures that
message 2 can't successfully forge a message 3. an attacker who sees only message 2 can't successfully forge a
message 3.
If a new value for <secret> is chosen while there are connections in If a new value for <secret> is chosen while there are connections in
the process of being initialized, an IKE_SA_INIT might be returned the process of being initialized, an IKE_SA_INIT might be returned
with other than the current <VersionIDofSecret>. The responder in with other than the current <VersionIDofSecret>. The responder in
that case MAY reject the message by sending another response with a that case MAY reject the message by sending another response with a
new cookie or it MAY keep the old value of <secret> around for a new cookie or it MAY keep the old value of <secret> around for a
short time and accept cookies computed from either one. The short time and accept cookies computed from either one. The
responder SHOULD NOT accept cookies indefinitely after <secret> is responder SHOULD NOT accept cookies indefinitely after <secret> is
changed, since that would defeat part of the denial of service changed, since that would defeat part of the denial of service
protection. The responder SHOULD change the value of <secret> protection. The responder SHOULD change the value of <secret>
frequently, especially if under attack. frequently, especially if under attack.
2.7 Cryptographic Algorithm Negotiation 2.7 Cryptographic Algorithm Negotiation
The payload type known as "SA" indicates a proposal for a set of The payload type known as "SA" indicates a proposal for a set of
choices of protocols (IKE, ESP, and/or AH) for the SA as well as choices of IPsec protocols (IKE, ESP, and/or AH) for the SA as well
cryptographic algorithms associated with each protocol. as cryptographic algorithms associated with each protocol.
An SA consists of one or more proposals. Each proposal includes one An SA consists of one or more proposals. Each proposal includes one
or more protocols (usually one). Each protocol contains one or more or more protocols (usually one). Each protocol contains one or more
transforms - each specifying a cryptographic algorithm. Each transforms - each specifying a cryptographic algorithm. Each
transform contains zero or more attributes (attributes are only transform contains zero or more attributes (attributes are only
needed if the transform identifier does not completely specify the needed if the transform identifier does not completely specify the
cryptographic algorithm). cryptographic algorithm).
This hierarchical structure was designed to be able to efficiently This hierarchical structure was designed to efficiently encode
encode proposals for cryptographic suites when the number of proposals for cryptographic suites when the number of supported
supported suites is large because multiple values are acceptable for suites is large because multiple values are acceptable for multiple
multiple transforms. The responder MUST choose a single suite, which transforms. The responder MUST choose a single suite, which MAY be
MAY be any subset of the SA proposal following the rules below: any subset of the SA proposal following the rules below:
Each proposal contains one or more protocols. If a proposal is Each proposal contains one or more protocols. If a proposal is
accepted, the SA response MUST contain the same protocols in the accepted, the SA response MUST contain the same protocols in the
same order as the proposal. At most one proposal MAY be accepted. same order as the proposal. The responder MUST accept a single
(Example: if a single proposal contains ESP and AH and that proposal or reject them all and return an error. (Example: if a
proposal is accepted, both ESP and AH MUST be accepted. If ESP and single proposal contains ESP and AH and that proposal is accepted,
AH are included in separate proposals, only one of them MAY be both ESP and AH MUST be accepted. If ESP and AH are included in
accepted). separate proposals, the responder MUST accept only one of them).
Each protocol in a proposal contains one or more transforms. Each Each IPsec protocol proposal contains one or more transforms. Each
transform contains a transform type. The accepted cryptographic transform contains a transform type. The accepted cryptographic
suite MUST contain exactly one transform of each type included in suite MUST contain exactly one transform of each type included in
the proposal. For example: if an ESP proposal includes transforms the proposal. For example: if an ESP proposal includes transforms
ENCR_3DES, ENCR_AES w/keysize 128, ENCR_AES w/keysize 256, ENCR_3DES, ENCR_AES w/keysize 128, ENCR_AES w/keysize 256,
AUTH_HMAC_MD5, and AUTH_HMAC_SHA, the accepted suite MUST contain AUTH_HMAC_MD5, and AUTH_HMAC_SHA, the accepted suite MUST contain
one of the ENCR_ transforms and one of the AUTH_ transforms. Thus one of the ENCR_ transforms and one of the AUTH_ transforms. Thus
six combinations are acceptable). six combinations are acceptable.
Since Alice sends her Diffie-Hellman value in the IKE_SA_INIT, she Since Alice sends her Diffie-Hellman value in the IKE_SA_INIT, she
must guess at the Diffie-Hellman group that Bob will select from her must guess at the Diffie-Hellman group that Bob will select from her
list of supported groups. If she guesses wrong, Bob will respond list of supported groups. If she guesses wrong, Bob will respond
with a Notify payload of type INVALID_KE_PAYLOAD indicating the with a Notify payload of type INVALID_KE_PAYLOAD indicating the
selected group. In this case, Alice MUST retry the IKE_SA_INIT with selected group. In this case, Alice MUST retry the IKE_SA_INIT with
the corrected Diffie-Hellman group. Alice MUST again propose her full the corrected Diffie-Hellman group. Alice MUST again propose her full
set of acceptable cryptographic suites because the rejection message set of acceptable cryptographic suites because the rejection message
was unauthenticated and otherwise an active attacker could trick was unauthenticated and otherwise an active attacker could trick
Alice and Bob into negotiating a weaker suite than a stronger one Alice and Bob into negotiating a weaker suite than a stronger one
that they both prefer. that they both prefer.
2.8 Rekeying 2.8 Rekeying
IKE, ESP, and AH security associations use secret keys which SHOULD IKE, ESP, and AH security associations use secret keys which SHOULD
only be used for a limited amount of time and to protect a limited only be used for a limited amount of time and to protect a limited
amount of data. This limits the lifetime of the entire security amount of data. This limits the lifetime of the entire security
association. When the lifetime of a security association expires the association. When the lifetime of a security association expires the
security association must not be used. If there is demand, new security association MUST NOT be used. If there is demand, new
security associations MAY be established. Reestablishment of security associations MAY be established. Reestablishment of
security associations to take the place of ones which expire is security associations to take the place of ones which expire is
referred to as "rekeying". referred to as "rekeying".
To allow for minimal IPsec implementations, the ability to rekey SAs To allow for minimal IPsec implementations, the ability to rekey SAs
without restarting the entire IKE_SA is optional. An implementation without restarting the entire IKE_SA is optional. An implementation
MAY refuse all CREATE_CHILD_SA requests within an IKE_SA. If an SA MAY refuse all CREATE_CHILD_SA requests within an IKE_SA. If an SA
has expired or is about to expire and rekeying attempts using the has expired or is about to expire and rekeying attempts using the
mechanisms described here fail, an implementation MUST close the mechanisms described here fail, an implementation MUST close the
IKE_SA and any associated CHILD_SAs and then MAY start new ones. IKE_SA and any associated CHILD_SAs and then MAY start new ones.
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between those endpoints, so the IKEv1 rekeying heuristic of deleting between those endpoints, so the IKEv1 rekeying heuristic of deleting
SAs on the basis of duplicate traffic selectors SHOULD NOT be used. SAs on the basis of duplicate traffic selectors SHOULD NOT be used.
The node that initiated the surviving rekeyed SA SHOULD delete the The node that initiated the surviving rekeyed SA SHOULD delete the
replaced SA after the new one is established. replaced SA after the new one is established.
There are timing windows - particularly in the presence of lost There are timing windows - particularly in the presence of lost
packets - where endpoints may not agree on the state of an SA. The packets - where endpoints may not agree on the state of an SA. The
responder to a CREATE_CHILD_SA MUST be prepared to accept messages on responder to a CREATE_CHILD_SA MUST be prepared to accept messages on
an SA before sending its response to the creation request, so there an SA before sending its response to the creation request, so there
is no ambiguity for the initiator. The initiator may begin sending on is no ambiguity for the initiator. The initiator MAY begin sending on
an SA as soon as it processes the response. The initiator, however, an SA as soon as it processes the response. The initiator, however,
cannot receive on a newly created SA until it receives and processes cannot receive on a newly created SA until it receives and processes
the response to its CREATE_CHILD_SA request. How, then, is the the response to its CREATE_CHILD_SA request. How, then, is the
responder to know when it is OK to send on the newly created SA? responder to know when it is OK to send on the newly created SA?
From a technical correctness and interoperability perspective, the From a technical correctness and interoperability perspective, the
responder MAY begin sending on an SA as soon as it sends its response responder MAY begin sending on an SA as soon as it sends its response
to the CREATE_CHILD_SA request. In some situations, however, this to the CREATE_CHILD_SA request. In some situations, however, this
could result in packets unnecessarily being dropped, so an could result in packets unnecessarily being dropped, so an
implementation MAY want to defer such sending. implementation MAY want to defer such sending.
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Traffic Selector (TS) payloads allow endpoints to communicate some of Traffic Selector (TS) payloads allow endpoints to communicate some of
the information from their SPD to their peers. TS payloads specify the information from their SPD to their peers. TS payloads specify
the selection criteria for packets that will be forwarded over the the selection criteria for packets that will be forwarded over the
newly set up SA. This can serve as a consistency check in some newly set up SA. This can serve as a consistency check in some
scenarios to assure that the SPDs are consistent. In others, it scenarios to assure that the SPDs are consistent. In others, it
guides the dynamic update of the SPD. guides the dynamic update of the SPD.
Two TS payloads appear in each of the messages in the exchange that Two TS payloads appear in each of the messages in the exchange that
creates a CHILD_SA pair. Each TS payload contains one or more Traffic creates a CHILD_SA pair. Each TS payload contains one or more Traffic
Selectors. Each Traffic Selector consists of an address range (IPv4 Selectors. Each Traffic Selector consists of an address range (IPv4
or IPv6), a port range, and a protocol ID. In support of the scenario or IPv6), a port range, and an IP protocol ID. In support of the
described in section 1.1.3, an initiator may request that the scenario described in section 1.1.3, an initiator may request that
responder assign an IP address and tell the initiator what it is. the responder assign an IP address and tell the initiator what it is.
IKEv2 allows the responder to choose a subset of the traffic proposed IKEv2 allows the responder to choose a subset of the traffic proposed
by the initiator. This could happen when the configuration of the by the initiator. This could happen when the configuration of the
two endpoints are being updated but only one end has received the new two endpoints are being updated but only one end has received the new
information. Since the two endpoints may be configured by different information. Since the two endpoints may be configured by different
people, the incompatibility may persist for an extended period even people, the incompatibility may persist for an extended period even
in the absence of errors. It also allows for intentionally different in the absence of errors. It also allows for intentionally different
configurations, as when one end is configured to tunnel all addresses configurations, as when one end is configured to tunnel all addresses
and depends on the other end to have the up to date list. and depends on the other end to have the up to date list.
The first of the two TS payloads is known as TSi (Traffic Selector- The first of the two TS payloads is known as TSi (Traffic Selector-
initiator). The second is known as TSr (Traffic Selector-responder). initiator). The second is known as TSr (Traffic Selector-responder).
TSi specifies the source address of traffic forwarded from (or the TSi specifies the source address of traffic forwarded from (or the
destination address of traffic forwarded to) the initiator of the destination address of traffic forwarded to) the initiator of the
CHILD_SA pair. TSr specifies the destination address of the traffic CHILD_SA pair. TSr specifies the destination address of the traffic
forwarded from (or the source address of the traffic forwarded to) forwarded from (or the source address of the traffic forwarded to)
the responder of the CHILD_SA pair. For example, if Alice initiates the responder of the CHILD_SA pair. For example, if Alice initiates
the creation of the CHILD_SA pair from Alice to Bob, and wishes to the creation of the CHILD_SA pair from Alice to Bob, and wishes to
tunnel all traffic from subnet 10.2.16.* on Alice's side to subnet tunnel all traffic from subnet 10.2.16.* on Alice's side to subnet
18.16.*.* on Bob's side, Alice would include a single traffic 10.16.*.* on Bob's side, Alice would include a single traffic
selector in each TS payload. TSi would specify the address range selector in each TS payload. TSi would specify the address range
(10.2.16.0 - 10.2.16.255) and TSr would specify the address range (10.2.16.0 - 10.2.16.255) and TSr would specify the address range
(18.16.0.0 - 18.16.255.255). Assuming that proposal was acceptable to (10.16.0.0 - 10.16.255.255). Assuming that proposal was acceptable to
Bob, he would send identical TS payloads back. Bob, he would send identical TS payloads back.
The Responder is allowed to narrow the choices by selecting a subset The Responder is allowed to narrow the choices by selecting a subset
of the traffic, for instance by eliminating or narrowing the range of of the traffic, for instance by eliminating or narrowing the range of
one or more members of the set of traffic selectors, provided the set one or more members of the set of traffic selectors, provided the set
does not become the NULL set. does not become the NULL set.
It is possible for the Responder's policy to contain multiple smaller It is possible for the Responder's policy to contain multiple smaller
ranges, all encompassed by the Initiator's traffic selector, and with ranges, all encompassed by the Initiator's traffic selector, and with
the Responder's policy being that each of those ranges should be sent the Responder's policy being that each of those ranges should be sent
over a different SA. Continuing the example above, Bob might have a over a different SA. Continuing the example above, Bob might have a
policy of being willing to tunnel those addresses to and from Alice, policy of being willing to tunnel those addresses to and from Alice,
but might require that each address pair be on a separately but might require that each address pair be on a separately
negotiated CHILD_SA. If Alice generated her request in response to an negotiated CHILD_SA. If Alice generated her request in response to an
incoming packet from 10.2.16.43 to 18.16.2.123, there would be no way incoming packet from 10.2.16.43 to 10.16.2.123, there would be no way
for Bob to determine which pair of addresses should be included in for Bob to determine which pair of addresses should be included in
this tunnel, and he would have to make his best guess or reject the this tunnel, and he would have to make his best guess or reject the
request with a status of SINGLE_PAIR_REQUIRED. request with a status of SINGLE_PAIR_REQUIRED.
To enable Bob to choose the appropriate range in this case, if Alice To enable Bob to choose the appropriate range in this case, if Alice
has initiated the SA due to a data packet, Alice SHOULD include as has initiated the SA due to a data packet, Alice SHOULD include as
the first traffic selector in each of TSi and TSr a very specific the first traffic selector in each of TSi and TSr a very specific
traffic selector including the addresses in the packet triggering the traffic selector including the addresses in the packet triggering the
request. In the example, Alice would include in TSi two traffic request. In the example, Alice would include in TSi two traffic
selectors: the first containing the address range (10.2.16.43 - selectors: the first containing the address range (10.2.16.43 -
10.2.16.43) and the source port and protocol from the packet and the 10.2.16.43) and the source port and IP protocol from the packet and
second containing (10.2.16.0 - 10.2.16.255) with all ports and the second containing (10.2.16.0 - 10.2.16.255) with all ports and IP
protocols. She would similarly include two traffic selectors in TSr. protocols. She would similarly include two traffic selectors in TSr.
If Bob's policy does not allow him to accept the entire set of If Bob's policy does not allow him to accept the entire set of
traffic selectors in Alice's request, but does allow him to accept traffic selectors in Alice's request, but does allow him to accept
the first selector of TSi and TSr, then Bob MUST narrow the traffic the first selector of TSi and TSr, then Bob MUST narrow the traffic
selectors to a subset that includes Alice's first choices. In this selectors to a subset that includes Alice's first choices. In this
example, Bob might respond with TSi being (10.2.16.43 - 10.2.16.43) example, Bob might respond with TSi being (10.2.16.43 - 10.2.16.43)
with all ports and protocols. with all ports and IP protocols.
If Alice creates the CHILD_SA pair not in response to an arriving If Alice creates the CHILD_SA pair not in response to an arriving
packet, but rather - say - upon startup, then there may be no packet, but rather - say - upon startup, then there may be no
specific addresses Alice prefers for the initial tunnel over any specific addresses Alice prefers for the initial tunnel over any
other. In that case, the first values in TSi and TSr MAY be ranges other. In that case, the first values in TSi and TSr MAY be ranges
rather than specific values, and Bob chooses a subset of Alice's TSi rather than specific values, and Bob chooses a subset of Alice's TSi
and TSr that are acceptable to him. If more than one subset is and TSr that are acceptable to him. If more than one subset is
acceptable but their union is not, Bob MUST accept some subset and acceptable but their union is not, Bob MUST accept some subset and
MAY include a Notify payload of type ADDITIONAL_TS_POSSIBLE to MAY include a Notify payload of type ADDITIONAL_TS_POSSIBLE to
indicate that Alice might want to try again. This case will only indicate that Alice might want to try again. This case will only
occur when Alice and Bob are configured differently from one another. occur when Alice and Bob are configured differently from one another.
If Alice and Bob agree on the granularity of tunnels, she will never If Alice and Bob agree on the granularity of tunnels, she will never
request a tunnel wider than Bob will accept. request a tunnel wider than Bob will accept.
2.10 Nonces 2.10 Nonces
The IKE_SA_INIT messages each contain a nonce. These nonces are used The IKE_SA_INIT messages each contain a nonce. These nonces are used
as inputs to cryptographic functions. The CREATE_CHILD_SA request as inputs to cryptographic functions. The CREATE_CHILD_SA request
and the CREATE_CHILD_SA response also contain nonces. These nonces and the CREATE_CHILD_SA response also contain nonces. These nonces
are used to add freshness to the key derivation technique used to are used to add freshness to the key derivation technique used to
obtain keys for CHILD_SA, and to extract strong pseudorandom bits obtain keys for CHILD_SA, and to ensure creation of strong
from the Diffie-Hellman key. Nonces used in IKEv2 MUST be randomly pseudorandom bits from the Diffie-Hellman key. Nonces used in IKEv2
chosen, MUST be at least 128 bits in size, and MUST be at least half MUST be randomly chosen, MUST be at least 128 bits in size, and MUST
the key size of the negotiated prf. If the same random number source be at least half the key size of the negotiated prf. ("prf" refers to
is used for both keys and nonces, care must be taken to ensure that "pseudo-random function", one of the cryptographic algorithms
the latter use does not compromise the former. negotiated in the IKE exchange). If the same random number source is
used for both keys and nonces, care must be taken to ensure that the
latter use does not compromise the former.
2.11 Address and Port Agility 2.11 Address and Port Agility
IKE runs over UDP ports 500 and 4500, and implicitly sets up ESP and IKE runs over UDP ports 500 and 4500, and implicitly sets up ESP and
AH associations for the same IP addresses it runs over. The IP AH associations for the same IP addresses it runs over. The IP
addresses and ports in the outer header are, however, not themselves addresses and ports in the outer header are, however, not themselves
cryptographically protected, and IKE is designed to work even through cryptographically protected, and IKE is designed to work even through
Network Address Translation (NAT) boxes. An implementation MUST Network Address Translation (NAT) boxes. An implementation MUST
accept incoming requests even if not received from UDP port 500 or accept incoming requests even if the source port is not 500 or 4500,
4500, and MUST respond to the address and port from which the request and MUST respond to the address and port from which the request was
was received, and from the address and port at which the request was received. It MUST specify the address and port at which the request
received. IKE functions identically over IPv4 or IPv6. was received as the source address and port in the response. IKE
functions identically over IPv4 or IPv6.
2.12 Reuse of Diffie-Hellman Exponentials 2.12 Reuse of Diffie-Hellman Exponentials
IKE generates keying material using an ephemeral Diffie-Hellman IKE generates keying material using an ephemeral Diffie-Hellman
exchange in order to gain the property of "perfect forward secrecy". exchange in order to gain the property of "perfect forward secrecy".
This means that once a connection is closed and its corresponding This means that once a connection is closed and its corresponding
keys are forgotten, even someone who has recorded all of the data keys are forgotten, even someone who has recorded all of the data
from the connection and gets access to all of the long term keys of from the connection and gets access to all of the long-term keys of
the two endpoints cannot reconstruct the keys used to protect the the two endpoints cannot reconstruct the keys used to protect the
conversation. conversation without doing a brute force search of the session key
space.
Achieving perfect forward secrecy requires that when a connection is Achieving perfect forward secrecy requires that when a connection is
closed, each endpoint MUST forget not only the keys used by the closed, each endpoint MUST forget not only the keys used by the
connection but any information that could be used to recompute those connection but any information that could be used to recompute those
keys. In particular, it MUST forget the secrets used in the Diffie- keys. In particular, it MUST forget the secrets used in the Diffie-
Hellman calculation and any state that may persist in the state of a Hellman calculation and any state that may persist in the state of a
pseudo-random number generator that could be used to recompute the pseudo-random number generator that could be used to recompute the
Diffie-Hellman secrets. Diffie-Hellman secrets.
Since the computing of Diffie-Hellman exponentials is computationally Since the computing of Diffie-Hellman exponentials is computationally
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negotiated: an encryption algorithm, an integrity protection negotiated: an encryption algorithm, an integrity protection
algorithm, a Diffie-Hellman group, and a pseudo-random function algorithm, a Diffie-Hellman group, and a pseudo-random function
(prf). The pseudo-random function is used for the construction of (prf). The pseudo-random function is used for the construction of
keying material for all of the cryptographic algorithms used in both keying material for all of the cryptographic algorithms used in both
the IKE_SA and the CHILD_SAs. the IKE_SA and the CHILD_SAs.
We assume that each encryption algorithm and integrity protection We assume that each encryption algorithm and integrity protection
algorithm uses a fixed size key, and that any randomly chosen value algorithm uses a fixed size key, and that any randomly chosen value
of that fixed size can serve as an appropriate key. For algorithms of that fixed size can serve as an appropriate key. For algorithms
that accept a variable length key, a fixed key size MUST be specified that accept a variable length key, a fixed key size MUST be specified
as part of the cryptographic transform negotiated. For integrity as part of the cryptographic transform negotiated. For algorithms
protection functions based on HMAC, the fixed key size is the size of for which not all values are valid keys (such as DES or 3DES with key
the output of the underlying hash function. When the prf function parity), they algorithm by which keys are derived from arbitrary
takes a variable length key, variable length data, and produces a values MUST be specified by the cryptographic transform. For
fixed length output (e.g., when using HMAC), the formulas in this integrity protection functions based on HMAC, the fixed key size is
document apply. When the key for the prf function has fixed length, the size of the output of the underlying hash function. When the prf
the data provided as a key is truncated or padded with zeros as function takes a variable length key, variable length data, and
necessary unless exceptional processing is explained following the produces a fixed length output (e.g., when using HMAC), the formulas
in this document apply. When the key for the prf function has fixed
length, the data provided as a key is truncated or padded with zeros
as necessary unless exceptional processing is explained following the
formula. formula.
Keying material will always be derived as the output of the Keying material will always be derived as the output of the
negotiated prf algorithm. Since the amount of keying material needed negotiated prf algorithm. Since the amount of keying material needed
may be greater than the size of the output of the prf algorithm, we may be greater than the size of the output of the prf algorithm, we
will use the prf iteratively. We will use the terminology prf+ to will use the prf iteratively. We will use the terminology prf+ to
describe the function that outputs a pseudo-random stream based on describe the function that outputs a pseudo-random stream based on
the inputs to a prf as follows: (where | indicates concatenation) the inputs to a prf as follows: (where | indicates concatenation)
prf+ (K,S) = T1 | T2 | T3 | T4 | ... prf+ (K,S) = T1 | T2 | T3 | T4 | ...
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(indicating that the quantities SK_d, SK_ai, SK_ar, SK_ei, and SK_er (indicating that the quantities SK_d, SK_ai, SK_ar, SK_ei, and SK_er
are taken in order from the generated bits of the prf+). g^ir is the are taken in order from the generated bits of the prf+). g^ir is the
shared secret from the ephemeral Diffie-Hellman exchange. g^ir is shared secret from the ephemeral Diffie-Hellman exchange. g^ir is
represented as a string of octets in big endian order padded with represented as a string of octets in big endian order padded with
zeros if necessary to make it the length of the modulus. Ni and Nr zeros if necessary to make it the length of the modulus. Ni and Nr
are the nonces, stripped of any headers. If the negotiated prf takes are the nonces, stripped of any headers. If the negotiated prf takes
a fixed length key and the lengths of Ni and Nr do not add up to that a fixed length key and the lengths of Ni and Nr do not add up to that
length, half the bits must come from Ni and half from Nr, taking the length, half the bits must come from Ni and half from Nr, taking the
first bits of each. first bits of each.
The two directions of flow use different keys. The keys used to The two directions of traffic flow use different keys. The keys used
protect messages from the original initiator are SK_ai and SK_ei. The to protect messages from the original initiator are SK_ai and SK_ei.
keys used to protect messages in the other direction are SK_ar and The keys used to protect messages in the other direction are SK_ar
SK_er. Each algorithm takes a fixed number of bits of keying and SK_er. Each algorithm takes a fixed number of bits of keying
material, which is specified as part of the algorithm. For integrity material, which is specified as part of the algorithm. For integrity
algorithms based on HMAC, the key size is always equal to the length algorithms based on HMAC, the key size is always equal to the length
of the output of the underlying hash function. of the output of the underlying hash function.
2.15 Authentication of the IKE_SA 2.15 Authentication of the IKE_SA
When not using extended authentication (see section 2.16), the peers When not using extended authentication (see section 2.16), the peers
are authenticated by having each sign (or MAC using a shared secret are authenticated by having each sign (or MAC using a shared secret
as the key) a block of data. For the responder, the octets to be as the key) a block of data. For the responder, the octets to be
signed start with the first octet of the first SPI in the header of signed start with the first octet of the first SPI in the header of
skipping to change at page 28, line 17 skipping to change at page 28, line 26
signature) are the initiator's nonce Ni (just the value, not the signature) are the initiator's nonce Ni (just the value, not the
payload containing it), and the value prf(SK_ar,IDr') where IDr' is payload containing it), and the value prf(SK_ar,IDr') where IDr' is
the responder's ID payload excluding the fixed header. Note that the responder's ID payload excluding the fixed header. Note that
neither the nonce Ni nor the value prf(SK_ar,IDr') are transmitted. neither the nonce Ni nor the value prf(SK_ar,IDr') are transmitted.
Similarly, the initiator signs the first message, starting with the Similarly, the initiator signs the first message, starting with the
first octet of the first SPI in the header and ending with the last first octet of the first SPI in the header and ending with the last
octet of the last payload. Appended to this (for purposes of octet of the last payload. Appended to this (for purposes of
computing the signature) are the responder's nonce Nr, and the value computing the signature) are the responder's nonce Nr, and the value
prf(SK_ai,IDi'). In the above calculation, IDi' and IDr' are the prf(SK_ai,IDi'). In the above calculation, IDi' and IDr' are the
entire ID payloads excluding the fixed header. It is critical to the entire ID payloads excluding the fixed header. It is critical to the
security of the exchange that each side sign the other side's nonce security of the exchange that each side sign the other side's nonce.
(see [SIGMA]).
Note that all of the payloads are included under the signature, Note that all of the payloads are included under the signature,
including any payload types not defined in this document. If the including any payload types not defined in this document. If the
first message of the exchange is sent twice (the second time with a first message of the exchange is sent twice (the second time with a
responder cookie and/or a different Diffie-Hellman group), it is the responder cookie and/or a different Diffie-Hellman group), it is the
second version of the message that is signed. second version of the message that is signed.
Optionally, messages 3 and 4 MAY include a certificate, or Optionally, messages 3 and 4 MAY include a certificate, or
certificate chain providing evidence that the key used to compute a certificate chain providing evidence that the key used to compute a
digital signature belongs to the name in the ID payload. The digital signature belongs to the name in the ID payload. The
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type of key each has. In particular, the initiator may be using a type of key each has. In particular, the initiator may be using a
shared key while the responder may have a public signature key and shared key while the responder may have a public signature key and
certificate. It will commonly be the case (but it is not required) certificate. It will commonly be the case (but it is not required)
that if a shared secret is used for authentication that the same key that if a shared secret is used for authentication that the same key
is used in both directions. Note that it is a common but typically is used in both directions. Note that it is a common but typically
insecure practice to have a shared key derived solely from a user insecure practice to have a shared key derived solely from a user
chosen password without incorporating another source of randomness. chosen password without incorporating another source of randomness.
This is typically insecure because user chosen passwords are unlikely This is typically insecure because user chosen passwords are unlikely
to have sufficient unpredictability to resist dictionary attacks and to have sufficient unpredictability to resist dictionary attacks and
these attacks are not prevented in this authentication method. these attacks are not prevented in this authentication method.
(Applications using password-based authentication for bootstrapping (Applications using password-based authentication for bootstrapping
and IKE_SA should use the authentication method in section 2.16, and IKE_SA should use the authentication method in section 2.16,
which is designed to prevent off-line dictionary attacks). The pre- which is designed to prevent off-line dictionary attacks). The pre-
shared key SHOULD contain as much unpredictability as the strongest shared key SHOULD contain as much unpredictability as the strongest
key being negotiated. In the case of a pre-shared key, the AUTH key being negotiated. In the case of a pre-shared key, the AUTH
value is computed as: value is computed as:
AUTH = prf(prf(Shared Secret,"Key Pad for IKEv2"), <message AUTH = prf(prf(Shared Secret,"Key Pad for IKEv2"), <message
octets>) octets>)
where the string "Key Pad for IKEv2" is ASCII encoded and not null where the string "Key Pad for IKEv2" is 17 ASCII characters without
terminated. The shared secret can be variable length. The pad string null termination. The shared secret can be variable length. The pad
is added so that if the shared secret is derived from a password, the string is added so that if the shared secret is derived from a
IKE implementation need not store the password in cleartext, but password, the IKE implementation need not store the password in
rather can store the value prf(Shared Secret,"Key Pad for IKEv2"), cleartext, but rather can store the value prf(Shared Secret,"Key Pad
which could not be used as a password equivalent for protocols other for IKEv2"), which could not be used as a password equivalent for
than IKEv2. As noted above, deriving the shared secret from a protocols other than IKEv2. As noted above, deriving the shared
password is not secure. This construction is used because it is secret from a password is not secure. This construction is used
anticipated that people will do it anyway. The management interface because it is anticipated that people will do it anyway. The
by which the Shared Secret is provided MUST accept ASCII strings of management interface by which the Shared Secret is provided MUST
at least 64 octets and MUST NOT add a null terminator before using accept ASCII strings of at least 64 octets and MUST NOT add a null
them as shared secrets. The management interface MAY accept other terminator before using them as shared secrets. The management
forms, like hex encoding. If the negotiated prf takes a fixed size interface MAY accept other forms, like hex encoding. If the
key, the shared secret MUST be of that fixed size. negotiated prf takes a fixed size key, the shared secret MUST be of
that fixed size.
2.16 Extended Authentication Protocol Methods 2.16 Extended Authentication Protocol Methods
In addition to authentication using public key signatures and shared In addition to authentication using public key signatures and shared
secrets, IKE supports authentication using methods defined in RFC secrets, IKE supports authentication using methods defined in RFC
2284 [EAP]. Typically, these methods are asymmetric (designed for a 2284 [EAP]. Typically, these methods are asymmetric (designed for a
user authenticating to a server), and they may not be mutual. For user authenticating to a server), and they may not be mutual. For
this reason, these protocols are typically used to authenticate the this reason, these protocols are typically used to authenticate the
initiator to the responder and are used in addition to a public key initiator to the responder and MUST be used in conjunction with a
signature based authentication of the responder to the initiator. public key signature based authentication of the responder to the
These methods are also referred to as "Legacy Authentication" initiator. These methods are often associated with mechanisms
mechanisms. referred to as "Legacy Authentication" mechanisms.
While this memo references [EAP] with the intent that new methods can While this memo references [EAP] with the intent that new methods can
be added in the future without updating this specification, the be added in the future without updating this specification, the
protocols expected to be used most commonly are fully documented here protocols expected to be used most commonly are documented here and
and in section 3.16. [EAP] defines an authentication protocol in section 3.16. [EAP] defines an authentication protocol requiring
requiring a variable number of messages. Extended Authentication is a variable number of messages. Extended Authentication is implemented
implemented in IKE as additional IKE_AUTH exchanges that MUST be in IKE as additional IKE_AUTH exchanges that MUST be completed in
completed in order to initialize the IKE_SA. order to initialize the IKE_SA.
An initiator indicates a desire to use extended authentication by An initiator indicates a desire to use extended authentication by
leaving out the AUTH payload from message 3. By including an IDi leaving out the AUTH payload from message 3. By including an IDi
payload but not an AUTH payload, the initiator has declared an payload but not an AUTH payload, the initiator has declared an
identity but has not proven it. If the responder is willing to use an identity but has not proven it. If the responder is willing to use an
extended authentication method, it will place an EAP payload in extended authentication method, it will place an EAP payload in
message 4 and defer sending SAr2, TSi, and TSr until initiator message 4 and defer sending SAr2, TSi, and TSr until initiator
authentication is complete in a subsequent IKE_AUTH exchange. In the authentication is complete in a subsequent IKE_AUTH exchange. In the
case of a minimal extended authentication, the initial SA case of a minimal extended authentication, the initial SA
establishment will appear as follows: establishment will appear as follows:
skipping to change at page 30, line 4 skipping to change at page 30, line 13
leaving out the AUTH payload from message 3. By including an IDi leaving out the AUTH payload from message 3. By including an IDi
payload but not an AUTH payload, the initiator has declared an payload but not an AUTH payload, the initiator has declared an
identity but has not proven it. If the responder is willing to use an identity but has not proven it. If the responder is willing to use an
extended authentication method, it will place an EAP payload in extended authentication method, it will place an EAP payload in
message 4 and defer sending SAr2, TSi, and TSr until initiator message 4 and defer sending SAr2, TSi, and TSr until initiator
authentication is complete in a subsequent IKE_AUTH exchange. In the authentication is complete in a subsequent IKE_AUTH exchange. In the
case of a minimal extended authentication, the initial SA case of a minimal extended authentication, the initial SA
establishment will appear as follows: establishment will appear as follows:
Initiator Responder Initiator Responder
----------- ----------- ----------- -----------
HDR, SAi1, KEi, Ni --> HDR, SAi1, KEi, Ni -->
<-- HDR, SAr1, KEr, Nr, [CERTREQ] <-- HDR, SAr1, KEr, Nr, [CERTREQ]
HDR, SK {IDi, [CERTREQ,] [IDr,] HDR, SK {IDi, [CERTREQ,] [IDr,]
SAi2, TSi, TSr} --> SAi2, TSi, TSr} -->
<-- HDR, SK {IDr, [CERT,] AUTH, <-- HDR, SK {IDr, [CERT,] AUTH,
EAP } EAP }
HDR, SK {EAP, [AUTH] } --> HDR, SK {EAP, AUTH} -->
<-- HDR, SK {EAP, [AUTH], <-- HDR, SK {EAP, AUTH,
SAr2, TSi, TSr } SAr2, TSi, TSr }
For EAP methods that create a shared key as a side effect of For EAP methods that create a shared key as a side effect of
authentication, that shared key MUST be used by both the Initiator authentication, that shared key MUST be used by both the Initiator
and Responder to generate an AUTH payload using the syntax for shared and Responder to generate AUTH payloads in messages 5 and 6 using the
secrets specified in section 2.15. The shared key generated during an syntax for shared secrets specified in section 2.15. The shared key
IKE exchange MUST NOT be used for any other purpose. generated during an IKE exchange MUST NOT be used for any other
purpose.
EAP methods that do not establish a shared key SHOULD NOT be used, as EAP methods that do not establish a shared key SHOULD NOT be used, as
they are subject to a number of man-in-the-middle attacks if these they are subject to a number of man-in-the-middle attacks [EAPMITM]
EAP methods are used in other protocols that do not use a server- if these EAP methods are used in other protocols that do not use a
authenticated tunnel. Please see the Security Considerations section server-authenticated tunnel. Please see the Security Considerations
for more details. If EAP methods that do not generate a shared key section for more details. If EAP methods that do not generate a
are used, there will be no AUTH payloads in the final messages. shared key are used, the AUTH payloads in messages 5 and 6 MUST be
generated using SK_ai and SK_ar respectively.
The Initiator of an IKE_SA using EAP SHOULD be capable of extending The Initiator of an IKE_SA using EAP SHOULD be capable of extending
the initial protocol exchange to at least ten IKE_AUTH exchanges in the initial protocol exchange to at least ten IKE_AUTH exchanges in
the event the Responder sends notification messages and/or retries the event the Responder sends notification messages and/or retries
the authentication prompt. The protocol terminates when the Responder the authentication prompt. The protocol terminates when the Responder
sends the Initiator an EAP payload containing either a success or sends the Initiator an EAP payload containing either a success or
failure type. failure type. In such an extended exchange, the EAP AUTH payloads
MUST be included in the first message each end sends after having
sufficient information to compute the key. This will usually be in
the last two messages of the exchange.
2.17 Generating Keying Material for CHILD_SAs 2.17 Generating Keying Material for CHILD_SAs
CHILD_SAs are created either by being piggybacked on the IKE_AUTH CHILD_SAs are created either by being piggybacked on the IKE_AUTH
exchange, or in a CREATE_CHILD_SA exchange. Keying material for them exchange, or in a CREATE_CHILD_SA exchange. Keying material for them
is generated as follows: is generated as follows:
KEYMAT = prf+(SK_d, Ni | Nr) KEYMAT = prf+(SK_d, Ni | Nr)
Where Ni and Nr are the Nonces from the IKE_SA_INIT exchange if this Where Ni and Nr are the Nonces from the IKE_SA_INIT exchange if this
request is the first CHILD_SA created or the fresh Ni and Nr from the request is the first CHILD_SA created or the fresh Ni and Nr from the
CREATE_CHILD_SA exchange if this is a subsequent creation. CREATE_CHILD_SA exchange if this is a subsequent creation.
For CREATE_CHILD_SA exchanges with PFS the keying material is defined For CREATE_CHILD_SA exchanges with PFS the keying material is defined
as: as:
KEYMAT = prf+(SK_d, g^ir (new) | Ni | Nr ) KEYMAT = prf+(SK_d, g^ir (new) | Ni | Nr )
where g^ir (new) is the shared secret from the ephemeral Diffie- where g^ir (new) is the shared secret from the ephemeral Diffie-
Hellman exchange of this CREATE_CHILD_SA exchange (represented as an Hellman exchange of this CREATE_CHILD_SA exchange (represented as an
octet string in big endian order padded with zeros if necessary to octet string in big endian order padded with zeros in the high order
make it the length of the modulus), bits if necessary to make it the length of the modulus).
A single CHILD_SA negotiation may result in multiple security A single CHILD_SA negotiation may result in multiple security
associations. ESP and AH SAs exist in pairs (one in each direction), associations. ESP and AH SAs exist in pairs (one in each direction),
and four SAs could be created in a single CHILD_SA negotiation if a and four SAs could be created in a single CHILD_SA negotiation if a
combination of ESP and AH is being negotiated. combination of ESP and AH is being negotiated.
Keying material is taken from the expanded KEYMAT in the following Keying material MUST be taken from the expanded KEYMAT in the
order: following order:
All keys for SAs carrying data from the initiator to the responder All keys for SAs carrying data from the initiator to the responder
are taken before SAs going in the reverse direction. are taken before SAs going in the reverse direction.
If multiple protocols are negotiated, keying material is taken in If multiple IPsec protocols are negotiated, keying material is
the order in which the protocol headers will appear in the taken in the order in which the protocol headers will appear in
encapsulated packet. the encapsulated packet.
If a single protocol has both encryption and authentication keys, If a single protocol has both encryption and authentication keys,
the encryption key is taken from the first octets of KEYMAT and the encryption key is taken from the first octets of KEYMAT and
the authentication key is taken from the next octets. the authentication key is taken from the next octets.
Each cryptographic algorithm takes a fixed number of bits of keying Each cryptographic algorithm takes a fixed number of bits of keying
material specified as part of the algorithm. material specified as part of the algorithm.
2.18 Rekeying IKE_SAs using a CREATE_CHILD_SA exchange 2.18 Rekeying IKE_SAs using a CREATE_CHILD_SA exchange
The CREATE_CHILD_SA exchange can be used to re-key an existing IKE_SA The CREATE_CHILD_SA exchange can be used to rekey an existing IKE_SA
(see section 2.8). New Initiator and Responder SPIs are supplied in (see section 2.8). New Initiator and Responder SPIs are supplied in
the SPI fields. The TS payloads are omitted when rekeying an IKE_SA. the SPI fields. The TS payloads are omitted when rekeying an IKE_SA.
SKEYSEED for the new IKE_SA is computed using SK_d from the existing SKEYSEED for the new IKE_SA is computed using SK_d from the existing
IKE_SA as follows: IKE_SA as follows:
SKEYSEED = prf(SK_d (old), [g^ir (new)] | Ni | Nr) SKEYSEED = prf(SK_d (old), [g^ir (new)] | Ni | Nr)
where g^ir (new) is the shared secret from the ephemeral Diffie- where g^ir (new) is the shared secret from the ephemeral Diffie-
Hellman exchange of this CREATE_CHILD_SA exchange (represented as an Hellman exchange of this CREATE_CHILD_SA exchange (represented as an
octet string in big endian order padded with zeros if necessary to octet string in big endian order padded with zeros if necessary to
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attributes the initiator wants returned in the response. attributes the initiator wants returned in the response.
For example, message from Initiator to Responder: For example, message from Initiator to Responder:
CP(CFG_REQUEST)= CP(CFG_REQUEST)=
INTERNAL_ADDRESS(0.0.0.0) INTERNAL_ADDRESS(0.0.0.0)
INTERNAL_NETMASK(0.0.0.0) INTERNAL_NETMASK(0.0.0.0)
INTERNAL_DNS(0.0.0.0) INTERNAL_DNS(0.0.0.0)
TSi = (0, 0-65536,0.0.0.0-255.255.255.255) TSi = (0, 0-65536,0.0.0.0-255.255.255.255)
TSr = (0, 0-65536,0.0.0.0-255.255.255.255) TSr = (0, 0-65536,0.0.0.0-255.255.255.255)
NOTE: Traffic Selectors are a (protocol, port range, address range) NOTE: Traffic Selectors contain (protocol, port range, address range)
Message from Responder to Initiator: Message from Responder to Initiator:
CP(CFG_REPLY)= CP(CFG_REPLY)=
INTERNAL_ADDRESS(192.168.219.202) INTERNAL_ADDRESS(10.168.219.202)
INTERNAL_NETMASK(255.255.255.0) INTERNAL_NETMASK(255.255.255.0)
INTERNAL_SUBNET(192.168.219.0/255.255.255.0) INTERNAL_SUBNET(10.168.219.0/255.255.255.0)
TSi = (0, 0-65536,192.168.219.202-192.168.219.202) TSi = (0, 0-65536,10.168.219.202-10.168.219.202)
TSr = (0, 0-65536,192.168.219.0-192.168.219.255) TSr = (0, 0-65536,10.168.219.0-10.168.219.255)
All returned values will be implementation dependent. As can be seen All returned values will be implementation dependent. As can be seen
in the above example, the IRAS MAY also send other attributes that in the above example, the IRAS MAY also send other attributes that
were not included in CP(CFG_REQUEST) and MAY ignore the non- were not included in CP(CFG_REQUEST) and MAY ignore the non-
mandatory attributes that it does not support. mandatory attributes that it does not support.
The responder MUST not send a CFG_REPLY without having first received The responder MUST NOT send a CFG_REPLY without having first received
a CP(CFG_REQUEST) from the initiator, because we do not want the IRAS a CP(CFG_REQUEST) from the initiator, because we do not want the IRAS
to perform an unnecessary configuration lookup if the IRAC cannot to perform an unnecessary configuration lookup if the IRAC cannot
process the REPLY. In the case where the IRAS's configuration process the REPLY. In the case where the IRAS's configuration
requires that CP be used for a given identity IDi, but IRAC has requires that CP be used for a given identity IDi, but IRAC has
failed to send a CP(CFG_REQUEST), IRAS MUST fail the request, and failed to send a CP(CFG_REQUEST), IRAS MUST fail the request, and
terminate the IKE exchange with a FAILED_CP_REQUIRED error. terminate the IKE exchange with a FAILED_CP_REQUIRED error.
2.20 Requesting the Peer's Version 2.20 Requesting the Peer's Version
An IKE peer wishing to inquire about the other peer's IKE software An IKE peer wishing to inquire about the other peer's IKE software
skipping to change at page 35, line 21 skipping to change at page 35, line 34
contains it. Compression associations disappear when the contains it. Compression associations disappear when the
corresponding ESP or AH SA goes away, and is not explicitly mentioned corresponding ESP or AH SA goes away, and is not explicitly mentioned
in any DELETE payload. in any DELETE payload.
Negotiation of IP compression is separate from the negotiation of Negotiation of IP compression is separate from the negotiation of
cryptographic parameters associated with a CHILD_SA. A node cryptographic parameters associated with a CHILD_SA. A node
requesting a CHILD_SA MAY advertise its support for one or more requesting a CHILD_SA MAY advertise its support for one or more
compression algorithms though one or more Notify payloads of type compression algorithms though one or more Notify payloads of type
IPCOMP_SUPPORTED. The response MAY indicate acceptance of a single IPCOMP_SUPPORTED. The response MAY indicate acceptance of a single
compression algorithm with a Notify payload of type IPCOMP_SUPPORTED. compression algorithm with a Notify payload of type IPCOMP_SUPPORTED.
These payloads MAY ONLY occur in the same messages that contain SA These payloads MUST NOT occur messages that do not contain SA
payloads. payloads.
While there has been discussion of allowing multiple compression While there has been discussion of allowing multiple compression
algorithms to be accepted and to have different compression algorithms to be accepted and to have different compression
algorithms available for the two directions of a CHILD_SA, algorithms available for the two directions of a CHILD_SA,
implementations of this specification MUST NOT accept an IPComp implementations of this specification MUST NOT accept an IPComp
algorithm that was not proposed, MUST NOT accept more than one, and algorithm that was not proposed, MUST NOT accept more than one, and
MUST NOT compress using an algorithm other than one proposed and MUST NOT compress using an algorithm other than one proposed and
accepted in the setup of the CHILD_SA. accepted in the setup of the CHILD_SA.
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port 500). port 500).
The specific requirements for supporting NAT traversal are listed The specific requirements for supporting NAT traversal are listed
below. Support for NAT traversal is optional. In this section only, below. Support for NAT traversal is optional. In this section only,
requirements listed as MUST only apply to implementations supporting requirements listed as MUST only apply to implementations supporting
NAT traversal. NAT traversal.
IKE MUST listen on port 4500 as well as port 500. IKE MUST respond IKE MUST listen on port 4500 as well as port 500. IKE MUST respond
to the IP address and port from which packets arrived. to the IP address and port from which packets arrived.
The IKE responder MUST include in its IKE_SA_INIT response Notify Both IKE initiator and responder MUST include in their IKE_SA_INIT
payloads of type NAT_DETECTION_SOURCE_IP and packets Notify payloads of type NAT_DETECTION_SOURCE_IP and
NAT_DETECTION_DESTINATION_IP. The IKE initiator MUST check these NAT_DETECTION_DESTINATION_IP. Those payloads can be used to detect
payloads if present and if they do not match the addresses in the if there is NAT between the hosts, and which end is behind the
outer packet MUST tunnel all future IKE, ESP, and AH packets NAT. The location of the payloads in the IKE_SA_INIT packets are
associated with this IKE_SA over UDP port 4500. To tunnel IKE just after the Ni and Nr payloads (before the optional CERTREQ
packets over UDP port 4500, the IKE header has four octets of zero payload).
prepended and the result immediately follows the UDP header. To
tunnel ESP packets over UDP port 4500, the ESP header immediately If none of the NAT_DETECTION_SOURCE_IP payload(s) received matches
follows the UDP header. Since the first four bytes of the ESP the hash of the source IP and port found from the IP header of the
header contain the SPI, and the SPI cannot validly be zero, it is packet containing the payload, it means that the the other end is
always possible to distinguish ESP and IKE messages. behind NAT (i.e someone along the route changed the source address
of the original packet to match the address of the NAT box). In
this case this end should allow dynamic update of the other ends
IP address, as described later.
If the NAT_DETECTION_DESTINATION_IP payload received does not
match the hash of the destination IP and port found from the IP
header of the packet containing the payload, it means that this
end is behind NAT (i.e the original sender sent the packet to
address of the NAT box, which then changed the destination address
to this host). In this case the this end should start sending
keepalive packets as explaind in [Hutt02].
The IKE initiator MUST check these payloads if present and if they
do not match the addresses in the outer packet MUST tunnel all
future IKE, ESP, and AH packets associated with this IKE_SA over
UDP port 4500.
To tunnel IKE packets over UDP port 4500, the IKE header has four
octets of zero prepended and the result immediately follows the
UDP header. To tunnel ESP packets over UDP port 4500, the ESP
header immediately follows the UDP header. Since the first four
bytes of the ESP header contain the SPI, and the SPI cannot
validly be zero, it is always possible to distinguish ESP and IKE
messages.
The original source and destination IP address required for the The original source and destination IP address required for the
transport mode TCP and UDP packet checksum fixup (see [Hutt02]) transport mode TCP and UDP packet checksum fixup (see [Hutt02])
obtained from the Traffic Selectors associated with the exchange. are obtained from the Traffic Selectors associated with the
In the case of NAT-T, the Traffic Selectors MUST contain exactly exchange. In the case of NAT-T, the Traffic Selectors MUST contain
one IP address which is then used as the original IP address. exactly one IP address which is then used as the original IP
address.
There are cases where a NAT box decides to remove mappings that There are cases where a NAT box decides to remove mappings that
are still alive (for example, the keepalive interval is too long, are still alive (for example, the keepalive interval is too long,
or the NAT box is rebooted). To recover in these cases, hosts that or the NAT box is rebooted). To recover in these cases, hosts that
are not behind a NAT SHOULD send all packets (including retried are not behind a NAT SHOULD send all packets (including
packets) to the IP address and port from the last valid retranmission packets) to the IP address and port from the last
authenticated packet from the other end. A host behind a NAT valid authenticated packet from the other end (i.e dynamically
SHOULD NOT do this because it opens a DoS attack possibility. Any update the address). A host behind a NAT SHOULD NOT do this
authenticated IKE packet or any authenticated UDP encapsulated ESP because it opens a DoS attack possibility. Any authenticated IKE
packet can be used to detect that the IP address or the port has packet or any authenticated UDP encapsulated ESP packet can be
changed. used to detect that the IP address or the port has changed.
Note that similar but probably not identical actions will likely Note that similar but probably not identical actions will likely
be needed to make IKE work with Mobile IP, but such processing is be needed to make IKE work with Mobile IP, but such processing is
not addressed by this document. not addressed by this document.
2.24 ECN (Explicit Congestion Notification) 2.24 ECN (Explicit Congestion Notification)
When IPsec tunnels behave as originally specified in [RFC 2401], ECN When IPsec tunnels behave as originally specified in [RFC 2401], ECN
usage is not appropriate for the outer IP headers because tunnel usage is not appropriate for the outer IP headers because tunnel
decapsulation processing discards ECN congestion indications to the decapsulation processing discards ECN congestion indications to the
skipping to change at page 43, line 5 skipping to change at page 44, line 5
o RESERVED (7 bits) - MUST be sent as zero; MUST be ignored on o RESERVED (7 bits) - MUST be sent as zero; MUST be ignored on
receipt. receipt.
o Payload Length (2 octets) - Length in octets of the current o Payload Length (2 octets) - Length in octets of the current
payload, including the generic payload header. payload, including the generic payload header.
3.3 Security Association Payload 3.3 Security Association Payload
The Security Association Payload, denoted SA in this memo, is used to The Security Association Payload, denoted SA in this memo, is used to
negotiate attributes of a security association. Assembly of Security negotiate attributes of a security association. Assembly of Security
Association Payloads requires great peace of mind. An SA may contain Association Payloads requires great peace of mind. An SA payload MAY
multiple proposals, ordered from most preferred to least preferred. contain multiple proposals. If there is more than one, they MUST be
Each proposal may contain multiple protocols (where a protocol is ordered from most preferred to least preferred. Each proposal may
IKE, ESP, or AH), each protocol may contain multiple transforms, and contain multiple IPsec protocols (where a protocol is IKE, ESP, or
each transform may contain multiple attributes. When parsing an SA, AH), each protocol MAY contain multiple transforms, and each
an implementation MUST check that the total Payload Length is transform MAY contain multiple attributes. When parsing an SA, an
consistent with the payload's internal lengths and counts. implementation MUST check that the total Payload Length is consistent
Proposals, Transforms, and Attributes each have their own variable with the payload's internal lengths and counts. Proposals,
length encodings. They are nested such that the Payload Length of an Transforms, and Attributes each have their own variable length
SA includes the combined contents of the SA, Proposal, Transform, and encodings. They are nested such that the Payload Length of an SA
includes the combined contents of the SA, Proposal, Transform, and
Attribute information. The length of a Proposal includes the lengths Attribute information. The length of a Proposal includes the lengths
of all Transforms and Attributes it contains. The length of a of all Transforms and Attributes it contains. The length of a
Transform includes the lengths of all Attributes it contains. Transform includes the lengths of all Attributes it contains.
The syntax of Security Associations, Proposals, Transforms, and The syntax of Security Associations, Proposals, Transforms, and
Attributes is based on ISAKMP, however the semantics are somewhat Attributes is based on ISAKMP, however the semantics are somewhat
different. The reason for the complexity and the hierarchy is to different. The reason for the complexity and the hierarchy is to
allow for multiple possible combinations of algorithms to be encoded allow for multiple possible combinations of algorithms to be encoded
in a single SA. Sometimes there is a choice of multiple algorithms, in a single SA. Sometimes there is a choice of multiple algorithms,
while other times there is a combination of algorithms. For example, while other times there is a combination of algorithms. For example,
an Initiator might want to propose using (AH w/MD5 and ESP w/3DES) OR an Initiator might want to propose using (AH w/MD5 and ESP w/3DES) OR
(ESP w/MD5 and 3DES). (ESP w/MD5 and 3DES).
One of the reasons the semantics of the SA payload has changed from One of the reasons the semantics of the SA payload has changed from
ISAKMP and IKEv1 is to make the encodings more compact in common ISAKMP and IKEv1 is to make the encodings more compact in common
cases. cases.
The Proposal structure contains within it a Proposal # and a The Proposal structure contains within it a Proposal # and an IPsec
SECURITY_PROTOCOL_ID. Each structure MUST have the same Proposal # protocol ID. Each structure MUST have the same Proposal # as the
as the previous one or be one (1) greater. The first Proposal MUST previous one or be one (1) greater. The first Proposal MUST have a
have a Proposal # of one (1). If two successive structures have the Proposal # of one (1). If two successive structures have the same
same Proposal number, it means that the proposal consists of the Proposal number, it means that the proposal consists of the first
first structure AND the second. So a proposal of AH AND ESP would structure AND the second. So a proposal of AH AND ESP would have two
have two proposal structures, one for AH and one for ESP and both proposal structures, one for AH and one for ESP and both would have
would have Proposal #1. A proposal of AH OR ESP would have two Proposal #1. A proposal of AH OR ESP would have two proposal
proposal structures, one for AH with proposal #1 and one for ESP with structures, one for AH with proposal #1 and one for ESP with proposal
proposal #2. #2.
Each Proposal/Protocol structure is followed by one or more transform Each Proposal/Protocol structure is followed by one or more transform
structures. The number of different transforms is generally structures. The number of different transforms is generally
determined by the Protocol. AH generally has a single transform: an determined by the Protocol. AH generally has a single transform: an
integrity check algorithm. ESP generally has two: an encryption integrity check algorithm. ESP generally has two: an encryption
algorithm AND an integrity check algorithm. IKE generally has four algorithm and an integrity check algorithm. IKE generally has four
transforms: a Diffie-Hellman group, an integrity check algorithm, a transforms: a Diffie-Hellman group, an integrity check algorithm, a
prf algorithm, and an encryption algorithm. For each Protocol, the prf algorithm, and an encryption algorithm. If an algorithm that
set of permissible transforms are assigned transform ID numbers, combines encryption and integrity protection is proposed, it MUST be
which appear in the header of each transform. proposed as an encryption algorithm and an integrity protection
algorithm MUST NOT be proposed. For each Protocol, the set of
permissible transforms are assigned transform ID numbers, which
appear in the header of each transform.
If there are multiple transforms with the same Transform Type, the If there are multiple transforms with the same Transform Type, the
proposal is an OR of those transforms. If there are multiple proposal is an OR of those transforms. If there are multiple
Transforms with different Transform Types, the proposal is an AND of Transforms with different Transform Types, the proposal is an AND of
the different groups. For example, to propose ESP with (3DES or IDEA) the different groups. For example, to propose ESP with (3DES or IDEA)
and (HMAC_MD5 or HMAC_SHA), the ESP proposal would contain two and (HMAC_MD5 or HMAC_SHA), the ESP proposal would contain two
Transform Type 1 candidates (one for 3DES and one for IDEA) and two Transform Type 1 candidates (one for 3DES and one for IDEA) and two
Transform Type 2 candidates (one for HMAC_MD5 and one for HMAC_SHA). Transform Type 2 candidates (one for HMAC_MD5 and one for HMAC_SHA).
This effectively proposes four combinations of algorithms. If the This effectively proposes four combinations of algorithms. If the
Initiator wanted to propose only a subset of those - say (3DES and Initiator wanted to propose only a subset of those - say (3DES and
HMAC_MD5) or (IDEA and HMAC_SHA), there is no way to encode that as HMAC_MD5) or (IDEA and HMAC_SHA), there is no way to encode that as
multiple transforms within a single Proposal. Instead, the Initiator multiple transforms within a single Proposal. Instead, the Initiator
would have to construct two different Proposals, each with two would have to construct two different Proposals, each with two
transforms. transforms.
A given transform MAY have one or more Attributes. Attributes are A given transform MAY have one or more Attributes. Attributes are
necessary when the transform can be used in more than one way, as necessary when the transform can be used in more than one way, as
when an encryption algorithm has a variable key size. The transform when an encryption algorithm has a variable key size. The transform
would specify the algorithm and the attribute would specify the key would specify the algorithm and the attribute would specify the key
size. Most transforms do not have attributes. size. Most transforms do not have attributes. A transform MUST NOT
have multiple attributes of the same type. To propose alternate
values for an attribute (for example, multiple key sizes for the AES
encryption algorithm), and implementation MUST include multiple
Transorms with the same Transform Type each with a single Attribute.
Note that the semantics of Transforms and Attributes are quite Note that the semantics of Transforms and Attributes are quite
different than in IKEv1. In IKEv1, a single Transform carried different than in IKEv1. In IKEv1, a single Transform carried
multiple algorithms for a protocol with one carried in the Transform multiple algorithms for a protocol with one carried in the Transform
and the others carried in the Attributes. and the others carried in the Attributes.
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 !C! RESERVED ! Payload Length ! ! Next Payload !C! RESERVED ! Payload Length !
skipping to change at page 45, line 12 skipping to change at page 46, line 15
The payload type for the Security Association Payload is thirty The payload type for the Security Association Payload is thirty
three (33). three (33).
3.3.1 Proposal Substructure 3.3.1 Proposal Substructure
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! 0 (last) or 2 ! RESERVED ! Proposal Length ! ! 0 (last) or 2 ! RESERVED ! Proposal Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Proposal # ! Protocol-Id ! SPI Size !# of Transforms! ! Proposal # ! Protocol ID ! SPI Size !# of Transforms!
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SPI (variable) ~ ~ SPI (variable) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ <Transforms> ~ ~ <Transforms> ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Proposal Substructure Figure 7: Proposal Substructure
skipping to change at page 45, line 46 skipping to change at page 46, line 49
o Proposal # (1 octet) - When a proposal is made, the first o Proposal # (1 octet) - When a proposal is made, the first
proposal in an SA MUST be #1, and subsequent proposals proposal in an SA MUST be #1, and subsequent proposals
MUST either be the same as the previous proposal (indicating MUST either be the same as the previous proposal (indicating
an AND of the two proposals) or one more than the previous an AND of the two proposals) or one more than the previous
proposal (indicating an OR of the two proposals). When a proposal (indicating an OR of the two proposals). When a
proposal is accepted, all of the proposal numbers in the proposal is accepted, all of the proposal numbers in the
SA MUST be the same and MUST match the number on the SA MUST be the same and MUST match the number on the
proposal sent that was accepted. proposal sent that was accepted.
o Protocol-Id (1 octet) - Specifies the protocol identifier o Protocol ID (1 octet) - Specifies the IPsec protocol
for the current negotiation. Zero (0) indicates IKE, identifier for the current negotiation. One (1) indicates
one (1) indicated ESP, and two (2) indicates AH. IKE, two (2) indicates AH, and three (3) indicates ESP.
o SPI Size (1 octet) - For an initial IKE_SA negotiation, o SPI Size (1 octet) - For an initial IKE_SA negotiation,
this field MUST be zero; the SPI is obtained from the this field MUST be zero; the SPI is obtained from the
outer header. During subsequent negotiations, outer header. During subsequent negotiations,
it is equal to the size, in octets, of the SPI of the it is equal to the size, in octets, of the SPI of the
corresponding protocol (8 for IKE, 4 for ESP and AH). corresponding protocol (8 for IKE, 4 for ESP and AH).
o # of Transforms (1 octet) - Specifies the number of o # of Transforms (1 octet) - Specifies the number of
transforms in this proposal. transforms in this proposal.
skipping to change at page 47, line 10 skipping to change at page 48, line 13
o Transform Type (1 octet) - The type of transform being specified o Transform Type (1 octet) - The type of transform being specified
in this transform. Different protocols support different in this transform. Different protocols support different
transform types. For some protocols, some of the transforms transform types. For some protocols, some of the transforms
may be optional. If a transform is optional and the initiator may be optional. If a transform is optional and the initiator
wishes to propose that the transform be omitted, no transform wishes to propose that the transform be omitted, no transform
of the given type is included in the proposal. If the of the given type is included in the proposal. If the
initiator wishes to make use of the transform optional to initiator wishes to make use of the transform optional to
the responder, she includes a transform substructure with the responder, she includes a transform substructure with
transform ID = 0 as one of the options. transform ID = 0 as one of the options.
o Transform ID (1 octet) - The specific instance of the transform o Transform ID (2 octets) - The specific instance of the transform
type being proposed. type being proposed.
Transform Type Values Transform Type Values
Transform Used In Transform Used In
Type Type
Encryption Algorithm 1 (IKE and ESP) Encryption Algorithm 1 (IKE and ESP)
Pseudo-random Function 2 (IKE) Pseudo-random Function 2 (IKE)
Integrity Algorithm 3 (IKE, AH, and optional in ESP) Integrity Algorithm 3 (IKE, AH, and optional in ESP)
Diffie-Hellman Group 4 (IKE and optional in AH and ESP) Diffie-Hellman Group 4 (IKE and optional in AH and ESP)
skipping to change at page 51, line 49 skipping to change at page 53, line 4
acceptable). If there are multiple proposals, the Responder MUST acceptable). If there are multiple proposals, the Responder MUST
choose a single proposal number and return all of the Proposal choose a single proposal number and return all of the Proposal
substructures with that Proposal number. If there are multiple substructures with that Proposal number. If there are multiple
Transforms with the same type the Responder MUST choose a single one. Transforms with the same type the Responder MUST choose a single one.
Any attributes of a selected transform MUST be returned unmodified. Any attributes of a selected transform MUST be returned unmodified.
The Initiator of an exchange MUST check that the accepted offer is The Initiator of an exchange MUST check that the accepted offer is
consistent with one of its proposals, and if not that response MUST consistent with one of its proposals, and if not that response MUST
be rejected. be rejected.
Negotiating Diffie-Hellman groups presents some special challenges. Negotiating Diffie-Hellman groups presents some special challenges.
SA offers include proposed attributes and a Diffie-Hellman public SA offers include proposed attributes and a Diffie-Hellman public
number (KE) in the same message. If in the initial exchange the number (KE) in the same message. If in the initial exchange the
Initiator offers to use one of several Diffie-Hellman groups, it Initiator offers to use one of several Diffie-Hellman groups, it
SHOULD pick the one the Responder is most likely to accept and SHOULD pick the one the Responder is most likely to accept and
include a KE corresponding to that group. If the guess turns out to include a KE corresponding to that group. If the guess turns out to
be wrong, the Responder will indicate the correct group in the be wrong, the Responder will indicate the correct group in the
response and the Initiator SHOULD pick an element of that group for response and the Initiator SHOULD pick an element of that group for
its KE value when retrying the first message. It SHOULD, however, its KE value when retrying the first message. It SHOULD, however,
continue to propose its full supported set of groups in order to continue to propose its full supported set of groups in order to
prevent a man in the middle downgrade attack. prevent a man in the middle downgrade attack.
Implementation Note: Implementation Note:
Certain negotiable attributes can have ranges or could have Certain negotiable attributes can have ranges or could have
multiple acceptable values. These include the key length of a multiple acceptable values. These include the key length of a
variable key length symmetric cipher. To further interoperability variable key length symmetric cipher. To further interoperability
and to support upgrading endpoints independently, implementers of and to support upgrading endpoints independently, implementers of
this protocol SHOULD accept values which they deem to supply this protocol SHOULD accept values which they deem to supply
greater security. For instance if a peer is configured to accept a greater security. For instance if a peer is configured to accept a
variable lengthed cipher with a key length of X bits and is variable lengthed cipher with a key length of X bits and is
offered that cipher with a larger key length an implementation offered that cipher with a larger key length, the implementation
SHOULD accept the offer. SHOULD accept the offer if it supports use of the longer key.
Support of this capability allows an implementation to express a Support of this capability allows an implementation to express a
concept of "at least" a certain level of security-- "a key length of concept of "at least" a certain level of security-- "a key length of
_at least_ X bits for cipher foo". _at least_ X bits for cipher Y".
3.4 Key Exchange Payload 3.4 Key Exchange Payload
The Key Exchange Payload, denoted KE in this memo, is used to The Key Exchange Payload, denoted KE in this memo, is used to
exchange Diffie-Hellman public numbers as part of a Diffie-Hellman exchange Diffie-Hellman public numbers as part of a Diffie-Hellman
key exchange. The Key Exchange Payload consists of the IKE generic key exchange. The Key Exchange Payload consists of the IKE generic
payload header followed by the Diffie-Hellman public value itself. payload header followed by the Diffie-Hellman public value itself.
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 53, line 8 skipping to change at page 54, line 12
Figure 10: Key Exchange Payload Format Figure 10: Key Exchange Payload Format
A key exchange payload is constructed by copying one's Diffie-Hellman A key exchange payload is constructed by copying one's Diffie-Hellman
public value into the "Key Exchange Data" portion of the payload. public value into the "Key Exchange Data" portion of the payload.
The length of the Diffie-Hellman public value MUST be equal to the The length of the Diffie-Hellman public value MUST be equal to the
length of the prime modulus over which the exponentiation was length of the prime modulus over which the exponentiation was
performed, prepending zero bits to the value if necessary. performed, prepending zero bits to the value if necessary.
The DH Group # identifies the Diffie-Hellman group in which the Key The DH Group # identifies the Diffie-Hellman group in which the Key
Exchange Data was computed (see Appendix B). If the selected Exchange Data was computed (see section 3.3.2). If the selected
proposal uses a different Diffie-Hellman group, the message MUST be proposal uses a different Diffie-Hellman group, the message MUST be
rejected with a Notify payload of type INVALID_KE_PAYLOAD. rejected with a Notify payload of type INVALID_KE_PAYLOAD.
The payload type for the Key Exchange payload is thirty four (34). The payload type for the Key Exchange payload is thirty four (34).
3.5 Identification Payloads 3.5 Identification Payloads
The Identification Payloads, denoted IDi and IDr in this memo, allow The Identification Payloads, denoted IDi and IDr in this memo, allow
peers to assert an identity to one another. This identity may be used peers to assert an identity to one another. This identity may be used
for policy lookup, but does not necessarily have to match anything in for policy lookup, but does not necessarily have to match anything in
skipping to change at page 54, line 52 skipping to change at page 56, line 7
The binary DER encoding of an ASN.1 X.500 GeneralName The binary DER encoding of an ASN.1 X.500 GeneralName
[X.509]. [X.509].
ID_KEY_ID 11 ID_KEY_ID 11
An opaque octet stream which may be used to pass an account An opaque octet stream which may be used to pass an account
name or to pass vendor-specific information necessary to do name or to pass vendor-specific information necessary to do
certain proprietary types of identification. certain proprietary types of identification.
Reserved to IANA 12-200
Reserved for private use 201-255
Two implementations will interoperate only if each can generate a Two implementations will interoperate only if each can generate a
type of ID acceptable to the other. To assure maximum type of ID acceptable to the other. To assure maximum
interoperability, implementations MUST be configurable to send at interoperability, implementations MUST be configurable to send at
least one of ID_IPV4_ADDR, ID_FQDN, ID_RFC822_ADDR, or ID_KEY_ID, and least one of ID_IPV4_ADDR, ID_FQDN, ID_RFC822_ADDR, or ID_KEY_ID, and
MUST be configurable to accept all of these types. Implementations MUST be configurable to accept all of these types. Implementations
SHOULD be capable of generating and accepting all of these types. SHOULD be capable of generating and accepting all of these types.
3.6 Certificate Payload 3.6 Certificate Payload
The Certificate Payload, denoted CERT in this memo, provides a means The Certificate Payload, denoted CERT in this memo, provides a means
skipping to change at page 56, line 7 skipping to change at page 57, line 15
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
Kerberos Token 6 Kerberos Token 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
X.509 Certificate - Attribute 10 X.509 Certificate - Attribute 10
Raw RSA Key 11 Raw RSA Key 11
Hash and URL of PKIX certificate 12 Hash and URL of X.509 certificate 12
Hash and URL of PKIX bundle 13 Hash and URL of X.509 bundle 13
RESERVED 14 - 200 RESERVED to IANA 14 - 200
PRIVATE USE 201 - 255 PRIVATE USE 201 - 255
o Certificate Data (variable length) - Actual encoding of o Certificate Data (variable length) - Actual encoding of
certificate data. The type of certificate is indicated certificate data. The type of certificate is indicated
by the Certificate Encoding field. by the Certificate Encoding field.
The payload type for the Certificate Payload is thirty seven (37). The payload type for the Certificate Payload is thirty seven (37).
Specific syntax is for some of the certificate type codes above is Specific syntax is for some of the certificate type codes above is
not defined in this document. The types whose syntax is defined in not defined in this document. The types whose syntax is defined in
this document are: this document are:
X.509 Certificate - Signature (4) contains a BER encoded X.509 X.509 Certificate - Signature (4) contains a BER encoded X.509
certificate. certificate whose public key is used to validate the sender's AUTH
payload.
Certificate Revocation List (7) contains a BER encoded X.509 Certificate Revocation List (7) contains a BER encoded X.509
certificate revocation list. certificate revocation list.
Raw RSA Key (11) contains a PKCS #1 encoded RSA key. Raw RSA Key (11) contains a PKCS #1 encoded RSA key.
Hash and URL of PKIX certificate (12) contains a 20 octet SHA-1 Hash and URL encodings (12-13) allow IKE messages to remain short
hash of a PKIX certificate followed by a variable length URL that by replacing long data structures with a 20 octet SHA-1 hash of
resolves to the BER encoded certificate itself. the replaced value followed by a variable length URL that resolves
to the BER encoded data structure itself. This improves efficiency
when the endpoints have certificate data cached and makes IKE less
subject to denial of service attacks that become easier to mount
when IKE messages are large enough to require IP fragmentation
[KPS03].
Hash and URL of PKIX bundle (13) contains a 20 octet SHA-1 hash of Use the following ASN.1 definition for an X.509 bundle:
a PKIX certificate bundle followed by a variable length URL the
resolves to the BER encoded certificate bundle itself. The bundle
is a BER encoded SEQUENCE of certificates and CRLs.
Use the following ASN.1 definition (suggested by Nicholas CertBundle
Williams): { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-cert-bundle(TBD) }
DEFINITION EXPLICIT TAGS ::= DEFINITIONS EXPLICIT TAGS ::=
BEGIN BEGIN
IMPORTS Certificate, CertificateList FROM PKIX1Explicit93 IMPORTS
Certificate, CertificateList
FROM PKIX1Explicit88
{ iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-explicit(18) } ;
CertificateOrCRL ::= CHOICE { CertificateOrCRL ::= CHOICE {
cert [0] Certificate, cert [0] Certificate,
crl [1] CertificateList crl [1] CertificateList }
}
CertificateBundle ::= SEQUENCE OF CertificateOrCRL CertificateBundle ::= SEQUENCE OF CertificateOrCRL
END
END
Implementations MUST be capable of being configured to send and Implementations MUST be capable of being configured to send and
accept up to four X.509 certificates in support of authentication. accept up to four X.509 certificates in support of authentication.
Implementations SHOULD be capable of being configured to send and Implementations SHOULD be capable of being configured to send and
accept Raw RSA keys and the two Hash and URL formats. If multiple accept Raw RSA keys and the first two Hash and URL formats. If
certificates are sent, the first certificate MUST contain the public multiple certificates are sent, the first certificate MUST contain
key used to sign the AUTH payload. The other certificates may be sent the public key used to sign the AUTH payload. The other certificates
in any order. may be sent in any order.
3.7 Certificate Request Payload 3.7 Certificate Request Payload
The Certificate Request Payload, denoted CERTREQ in this memo, The Certificate Request Payload, denoted CERTREQ in this memo,
provides a means to request preferred certificates via IKE and can provides a means to request preferred certificates via IKE and can
appear in the IKE_INIT_SA response and/or the IKE_AUTH request. appear in the IKE_INIT_SA response and/or the IKE_AUTH request.
Certificate Request payloads MAY be included in an exchange when the Certificate Request payloads MAY be included in an exchange when the
sender needs to get the certificate of the receiver. If multiple CAs sender needs to get the certificate of the receiver. If multiple CAs
are trusted and the cert encoding does not allow a list, then are trusted and the cert encoding does not allow a list, then
multiple Certificate Request payloads SHOULD be transmitted. multiple Certificate Request payloads SHOULD be transmitted.
skipping to change at page 61, line 12 skipping to change at page 62, line 12
message to indicate sender capabilities or to modify the meaning of message to indicate sender capabilities or to modify the meaning of
the request. the request.
The Notify Payload is defined as follows: The Notify Payload is defined as follows:
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 !C! RESERVED ! Payload Length ! ! Next Payload !C! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! S_Protocol_ID ! SPI Size ! Notify Message Type ! ! Protocol ID ! SPI Size ! Notify Message Type !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Security Parameter Index (SPI) ~ ~ Security Parameter Index (SPI) ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Notification Data ~ ~ Notification Data ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: Notification Payload Format Figure 16: Notification Payload Format
o SECURITY_PROTOCOL_ID (1 octet) - If this notification concerns o Protocol ID (1 octet) - If this notification concerns
an existing SA, this field indicates the type of that SA. an existing SA, this field indicates the type of that SA.
For IKE_SA notifications, this field MUST be one (1). For For IKE_SA notifications, this field MUST be one (1). For
notifications concerning IPsec SAs this field MUST contain notifications concerning IPsec SAs this field MUST contain
either (2) to indicate AH or (3) to indicate ESP. For either (2) to indicate AH or (3) to indicate ESP. For
notifications which do not relate to an existing SA, this notifications which do not relate to an existing SA, this
field MUST be sent as zero and MUST be ignored on receipt. field MUST be sent as zero and MUST be ignored on receipt.
All other values for this field are reserved to IANA for future All other values for this field are reserved to IANA for future
assignment. assignment.
o SPI Size (1 octet) - Length in octets of the SPI as defined by o SPI Size (1 octet) - Length in octets of the SPI as defined by
the SECURITY_PROTOCOL_ID or zero if no SPI is applicable. For a the IPsec protocol ID or zero if no SPI is applicable. For a
notification concerning the IKE_SA, the SPI Size MUST be zero. notification concerning the IKE_SA, the SPI Size MUST be zero.
o Notify Message Type (2 octets) - Specifies the type of o Notify Message Type (2 octets) - Specifies the type of
notification message. notification message.
o SPI (variable length) - Security Parameter Index. o SPI (variable length) - Security Parameter Index.
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 transmitted in addition to the Notify Message Type. Values for
this field are type specific (see below). this field are type specific (see below).
skipping to change at page 63, line 5 skipping to change at page 64, line 5
specified in the header. The closest version number that the specified in the header. The closest version number that the
recipient can support will be in the reply header. recipient can support will be in the reply header.
INVALID_SYNTAX 7 INVALID_SYNTAX 7
Indicates the IKE message was received was invalid because Indicates the IKE message was received was invalid because
some type, length, or value was out of range or because the some type, length, or value was out of range or because the
request was rejected for policy reasons. To avoid a denial request was rejected for policy reasons. To avoid a denial
of service attack using forged messages, this status may of service attack using forged messages, this status may
only be returned for and in an encrypted packet if the only be returned for and in an encrypted packet if the
MESSAGE_ID and cryptographic checksum were valid. To avoid message ID and cryptographic checksum were valid. To avoid
leaking information to someone probing a node, this status leaking information to someone probing a node, this status
MUST be sent in response to any error not covered by one of MUST be sent in response to any error not covered by one of
the other status types. To aid debugging, more detailed the other status types. To aid debugging, more detailed
error information SHOULD be written to a console or log. error information SHOULD be written to a console or log.
INVALID_MESSAGE_ID 9 INVALID_MESSAGE_ID 9
Sent when an IKE MESSAGE_ID outside the supported window is Sent when an IKE message ID outside the supported window is
received. This Notify MUST NOT be sent in a response; the received. This Notify MUST NOT be sent in a response; the
invalid request MUST NOT be acknowledged. Instead, inform invalid request MUST NOT be acknowledged. Instead, inform
the other side by initiating an INFORMATIONAL exchange with the other side by initiating an INFORMATIONAL exchange with
Notification data containing the four octet invalid Notification data containing the four octet invalid message
MESSAGE_ID. Sending this notification is optional and ID. Sending this notification is optional and notifications
notifications of this type MUST be rate limited. of this type MUST be rate limited.
INVALID_SPI 11 INVALID_SPI 11
MAY be sent in an IKE INFORMATIONAL Exchange when a node MAY be sent in an IKE INFORMATIONAL Exchange when a node
receives an ESP or AH packet with an invalid SPI. The receives an ESP or AH packet with an invalid SPI. The
Notification Data contains the SPI of the invalid packet. Notification Data contains the SPI of the invalid packet.
This usually indicates a node has rebooted and forgotten an This usually indicates a node has rebooted and forgotten an
SA. If this Informational Message is sent outside the SA. If this Informational Message is sent outside the
context of an IKE_SA, it should only be used by the context of an IKE_SA, it should only be used by the
recipient as a "hint" that something might be wrong (because recipient as a "hint" that something might be wrong (because
skipping to change at page 64, line 37 skipping to change at page 65, line 37
Sent by responder in the case where CP(CFG_REQUEST) was Sent by responder in the case where CP(CFG_REQUEST) was
expected but not received, and so is a conflict with locally expected but not received, and so is a conflict with locally
configured policy. There is no associated data. configured policy. There is no associated data.
TS_UNACCEPTABLE 38 TS_UNACCEPTABLE 38
Indicates that none of the addresses/protocols/ports in the Indicates that none of the addresses/protocols/ports in the
supplied traffic selectors is acceptable. supplied traffic selectors is acceptable.
INVALID_SELECTORS 39
MAY be sent in an IKE INFORMATIONAL Exchange when a node
receives an ESP or AH packet whose selectors do not match
those of the SA on which it was delivered (and which caused
the packet to be dropped). The Notification Data contains
the start of the offending packet (as in ICMP messages) and
the SPI field of the notification is set to match the SPI of
the IPsec SA.
RESERVED TO IANA - Error types 39 - 8191 RESERVED TO IANA - Error types 39 - 8191
Private Use - Errors 8192 - 16383 Private Use - Errors 8192 - 16383
NOTIFY MESSAGES - STATUS TYPES Value NOTIFY MESSAGES - STATUS TYPES Value
------------------------------ ----- ------------------------------ -----
INITIAL_CONTACT 16384 INITIAL_CONTACT 16384
This notification asserts that this IKE_SA is the only This notification asserts that this IKE_SA is the only
IKE_SA currently active between the authenticated IKE_SA currently active between the authenticated
identities. It MAY be sent when an IKE_SA is established identities. It MAY be sent when an IKE_SA is established
after a crash, and the recipient MAY use this information to after a crash, and the recipient MAY use this information to
delete any other IKE_SAs it has to the same authenticated delete any other IKE_SAs it has to the same authenticated
skipping to change at page 67, line 45 skipping to change at page 69, line 5
Private Use - STATUS TYPES 40960 - 65535 Private Use - STATUS TYPES 40960 - 65535
3.11 Delete Payload 3.11 Delete Payload
The Delete Payload, denoted D in this memo, contains a protocol The Delete Payload, denoted D in this memo, contains a protocol
specific security association identifier that the sender has removed specific security association identifier that the sender has removed
from its security association database and is, therefore, no longer from its security association database and is, therefore, no longer
valid. Figure 17 shows the format of the Delete Payload. It is valid. Figure 17 shows the format of the Delete Payload. It is
possible to send multiple SPIs in a Delete payload, however, each SPI possible to send multiple SPIs in a Delete payload, however, each SPI
MUST be for the same protocol. Mixing of Protocol Identifiers MUST MUST be for the same protocol. Mixing of protocol identifiers MUST
NOT be performed in a the Delete payload. It is permitted, however, NOT be performed in a the Delete payload. It is permitted, however,
to include multiple Delete payloads in a single INFORMATIONAL to include multiple Delete payloads in a single INFORMATIONAL
Exchange where each Delete payload lists SPIs for a different Exchange where each Delete payload lists SPIs for a different
protocol. protocol.
Deletion of the IKE_SA is indicated by a SECURITY_PROTOCOL_ID of 1 Deletion of the IKE_SA is indicated by a protocol ID of 1 (IKE) but
(IKE) but no SPIs. Deletion of a CHILD_SA, such as ESP or AH, will no SPIs. Deletion of a CHILD_SA, such as ESP or AH, will contain the
contain the SECURITY_PROTOCOL_ID of that protocol (2 for AH, 3 for IPsec protocol ID of that protocol (2 for AH, 3 for ESP) and the SPI
ESP) and the SPI is the SPI the sending endpoint would expect in is the SPI the sending endpoint would expect in inbound ESP or AH
inbound ESP or AH packets. packets.
The Delete Payload is defined as follows: The Delete Payload is defined as follows:
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 !C! RESERVED ! Payload Length ! ! Next Payload !C! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! S_PROTOCOL_ID ! SPI Size ! # of SPIs ! ! Protocol ID ! SPI Size ! # of SPIs !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Security Parameter Index(es) (SPI) ~ ~ Security Parameter Index(es) (SPI) ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Delete Payload Format Figure 17: Delete Payload Format
o SECURITY_PROTOCOL_ID (1 octet) - Must be 1 for an IKE_SA, 2 o Protocol ID (1 octet) - Must be 1 for an IKE_SA, 2 for AH, or
for AH, or 3 for ESP. 3 for ESP.
o SPI Size (1 octet) - Length in octets of the SPI as defined by o SPI Size (1 octet) - Length in octets of the SPI as defined by
the SECURITY_PROTOCOL_ID. Zero for IKE (SPI is in message the protocol ID. It MUST be zero for IKE (SPI is in message
header) or four for AH and ESP. header) or four for AH and ESP.
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. The length of this specific security association(s) to delete. The length of this
field is determined by the SPI Size and # of SPIs fields. field is determined by the SPI Size and # of SPIs fields.
The payload type for the Delete Payload is forty two (42). The payload type for the Delete Payload is forty two (42).
skipping to change at page 71, line 10 skipping to change at page 72, line 10
The payload type for the Traffic Selector payload is forty four (44) The payload type for the Traffic Selector payload is forty four (44)
for addresses at the initiator's end of the SA and forty five (45) for addresses at the initiator's end of the SA and forty five (45)
for addresses at the responder's end. for addresses at the responder's end.
3.13.1 Traffic Selector 3.13.1 Traffic Selector
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! TS Type ! Protocol_ID* | Selector Length | ! TS Type !IP Protocol ID*| Selector Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start_Port* | End_Port* | | Start Port* | End Port* |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Starting Address* ~ ~ Starting Address* ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! !
~ Ending Address* ~ ~ Ending Address* ~
! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: Traffic Selector Figure 20: Traffic Selector
*Note: all fields other than TS Type and Selector Length depend on *Note: all fields other than TS Type and Selector Length depend on
the TS Type. The fields shown are for TS Types 7 and 8, the only two the TS Type. The fields shown are for TS Types 7 and 8, the only two
values currently defined. values currently defined.
o TS Type (one octet) - Specifies the type of traffic selector. o TS Type (one octet) - Specifies the type of traffic selector.
o Protocol ID (1 octet) - Value specifying an associated IP o IP protocol ID (1 octet) - Value specifying an associated IP
protocol ID (e.g., UDP/TCP/ICMP). A value of zero means that protocol ID (e.g., UDP/TCP/ICMP). A value of zero means that
the Protocol ID is not relevant to this traffic selector-- the protocol ID is not relevant to this traffic selector--
the SA can carry all protocols. the SA can carry all protocols.
o Selector Length - Specifies the length of this Traffic o Selector Length - Specifies the length of this Traffic
Selector Substructure including the header. Selector Substructure including the header.
o Start_Port (2 octets) - Value specifying the smallest port o Start Port (2 octets) - Value specifying the smallest port
number allowed by this Traffic Selector. For protocols for number allowed by this Traffic Selector. For protocols for
which port is undefined, or if all ports are allowed by which port is undefined, or if all ports are allowed by
this Traffic Selector, this field MUST be zero. For the this Traffic Selector, this field MUST be zero. For the
ICMP protocol, the two one octet fields Type and Code are ICMP protocol, the two one octet fields Type and Code are
treated as a single 16 bit integer port number for the treated as a single 16 bit integer port number for the
purposes of filtering based on this field. purposes of filtering based on this field.
o End_Port (2 octets) - Value specifying the largest port o End Port (2 octets) - Value specifying the largest port
number allowed by this Traffic Selector. For protocols for number allowed by this Traffic Selector. For protocols for
which port is undefined, or if all ports are allowed by which port is undefined, or if all ports are allowed by
this Traffic Selector, this field MUST be 65535. For the this Traffic Selector, this field MUST be 65535. For the
ICMP protocol, the two one octet fields Type and Code are ICMP protocol, the two one octet fields Type and Code are
treated as a single 16 bit integer port number for the treated as a single 16 bit integer port number for the
purposed of filtering based on this field. purposed of filtering based on this field.
o Starting Address - The smallest address included in this o Starting Address - The smallest address included in this
Traffic Selector (length determined by TS type). Traffic Selector (length determined by TS type).
skipping to change at page 81, line 11 skipping to change at page 82, line 11
Note that since IKE passes an indication of initiator identity in Note that since IKE passes an indication of initiator identity in
message 3 of the protocol, EAP based prompts for Identity SHOULD NOT message 3 of the protocol, EAP based prompts for Identity SHOULD NOT
be used. be used.
4 Conformance Requirements 4 Conformance Requirements
In order to assure that all implementations of IKEv2 can In order to assure that all implementations of IKEv2 can
interoperate, there are MUST support requirements in addition to interoperate, there are MUST support requirements in addition to
those listed elsewhere. Of course, IKEv2 is a security protocol, and those listed elsewhere. Of course, IKEv2 is a security protocol, and
one of its major functions is preventing the bad guys from one of its major functions is to only allow authorized parties to
interoperating with one's systems. So a particular implementation may successfully complete establishment of SAs. So a particular
be configured with any of a number of restrictions concerning implementation may be configured with any of a number of restrictions
algorithms and trusted authorities that will prevent universal concerning algorithms and trusted authorities that will prevent
interoperability. universal interoperability.
IKEv2 is designed to permit minimal implementations that can IKEv2 is designed to permit minimal implementations that can
interoperate with all compliant implementations. There are a series interoperate with all compliant implementations. There are a series
of optional features that can easily be ignored by a particular of optional features that can easily be ignored by a particular
implementation if it does not support that feature. Those features implementation if it does not support that feature. Those features
include: include:
Ability to negotiate SAs through a NAT and tunnel the resulting ESP Ability to negotiate SAs through a NAT and tunnel the resulting
SA over UDP. ESP SA over UDP.
Ability to request (and respond to a request for) a temporary IP Ability to request (and respond to a request for) a temporary IP
address on the remote end of a tunnel. address on the remote end of a tunnel.
Ability to support various types of legacy authentication. Ability to support various types of legacy authentication.
Ability to support window sizes greater than one. Ability to support window sizes greater than one.
Ability to establish multiple ESP and/or AH SAs within a single Ability to establish multiple ESP and/or AH SAs within a single
IKE_SA. IKE_SA.
Ability to rekey SAs. Ability to rekey SAs.
To assure interoperability, all implementations MUST be capable of To assure interoperability, all implementations MUST be capable of
parsing all payload types (if only to skip over them) and to ignore parsing all payload types (if only to skip over them) and to ignore
payload types that it does not support unless the critical bit is set payload types that it does not support unless the critical bit is set
in the payload header. If the critical bit is set in an unsupported in the payload header. If the critical bit is set in an unsupported
payload header, all implementations MUST reject the messages payload header, all implementations MUST reject the messages
containing those payloads. containing those payloads.
Every implementation MUST be capable of doing four message Every implementation MUST be capable of doing four message
IKE_SA_INIT and IKE_AUTH exchanges establishing two SAs (one for IKE, IKE_SA_INIT and IKE_AUTH exchanges establishing two SAs (one for IKE,
skipping to change at page 83, line 11 skipping to change at page 84, line 11
Shared key authentication where the ID passes is any of ID_KEY_ID, Shared key authentication where the ID passes is any of ID_KEY_ID,
ID_FQDN, or ID_RFC822_ADDR. ID_FQDN, or ID_RFC822_ADDR.
Authentication where the responder is authenticated using PKIX Authentication where the responder is authenticated using PKIX
Certificates and the initiator is authenticated using shared key Certificates and the initiator is authenticated using shared key
authentication. authentication.
5 Security Considerations 5 Security Considerations
Repeated re-keying using CREATE_CHILD_SA without PFS leaves all SAs Repeated rekeying using CREATE_CHILD_SA without PFS leaves all SAs
vulnerable to cryptanalysis of a single key or overrun of either vulnerable to cryptanalysis of a single key or overrun of either
endpoint. Implementers should take note of this fact and set a limit endpoint. Implementers should take note of this fact and set a limit
on CREATE_CHILD_SA exchanges between exponentiations. This memo does on CREATE_CHILD_SA exchanges between exponentiations. This memo does
not prescribe such a limit. not prescribe such a limit.
The strength of a key derived from a Diffie-Hellman exchange using The strength of a key derived from a Diffie-Hellman exchange using
any of the groups defined here depends on the inherent strength of any of the groups defined here depends on the inherent strength of
the group, the size of the exponent used, and the entropy provided by the group, the size of the exponent used, and the entropy provided by
the random number generator used. Due to these inputs it is difficult the random number generator used. Due to these inputs it is difficult
to determine the strength of a key for any of the defined groups. to determine the strength of a key for any of the defined groups.
skipping to change at page 83, line 47 skipping to change at page 84, line 47
elliptical curve groups may greatly increase strength using much elliptical curve groups may greatly increase strength using much
smaller numbers. smaller numbers.
It is assumed that all Diffie-Hellman exponents are erased from It is assumed that all Diffie-Hellman exponents are erased from
memory after use. In particular, these exponents MUST NOT be derived memory after use. In particular, these exponents MUST NOT be derived
from long-lived secrets like the seed to a pseudo-random generator from long-lived secrets like the seed to a pseudo-random generator
that is not erased after use. that is not erased after use.
The strength of all keys are limited by the size of the output of the The strength of all keys are limited by the size of the output of the
negotiated prf function. For this reason, a prf function whose output negotiated prf function. For this reason, a prf function whose output
is less than 128 bits (e.g., 3DES-CBC) MUST never be used with this is less than 128 bits (e.g., 3DES-CBC) MUST NOT be used with this
protocol. protocol.
The security of this protocol is critically dependent on the The security of this protocol is critically dependent on the
randomness of the randomly chosen parameters. These should be randomness of the randomly chosen parameters. These should be
generated by a strong random or properly seeded pseudo-random source generated by a strong random or properly seeded pseudo-random source
(see [RFC1750]). Implementers should take care to ensure that use of (see [RFC1750]). Implementers should take care to ensure that use of
random numbers for both keys and nonces is engineered in a fashion random numbers for both keys and nonces is engineered in a fashion
that does not undermine the security of the keys. that does not undermine the security of the keys.
For information on the rationale of many of the cryptographic design For information on the rationale of many of the cryptographic design
choices in this protocol, see [SIGMA]. choices in this protocol, see [SIGMA].
When using pre-shared keys, a critical consideration is how to assure When using pre-shared keys, a critical consideration is how to assure
the randomness of these secrets. The strongest practice is to ensure the randomness of these secrets. The strongest practice is to ensure
that any pre-shared key contain as much randomness as the strongest that any pre-shared key contain as much randomness as the strongest
key being negotiated. Deriving a shared secret from a password, name, key being negotiated. Deriving a shared secret from a password, name,
or other low entropy source is not secure. These sources are subject or other low entropy source is not secure. These sources are subject
to dictionary and social engineering attacks, among others. to dictionary and social engineering attacks, among others.
The NAT_DETECTION_*_IP notifications contain a hash of the addresses The NAT_DETECTION_*_IP notifications contain a hash of the addresses
and ports in an attempt to hide internal IP addresses behind a NAT and ports in an attempt to hide internal IP addresses behind a NAT.
from the IKE peer. As the IPv4 address space is only 32 bits, and it Since the IPv4 address space is only 32 bits, and it is usually very
is usually very sparse, it might be possible for the attacker to find sparse, it would be possible for an attacker to find out the internal
out the internal address used behind the NAT box by trying all address used behind the NAT box by trying all possible IP-addresses
possible IP-addresses and trying to find the matching hash. The port and trying to find the matching hash. The port numbers are normally
numbers are normally fixed to 500, and the SPIs can be extracted from fixed to 500, and the SPIs can be extracted from the packet. This
the packet. This limits the hash calculations down to 2^32. If reduces the number of hash calculations to 2^32. With an educated
educated guess of use of private address space is done, then the guess of the use of private address space, the number of hash
number of hash calculations needed to find out the internal IP calculations is much smaller. Designers should therefore not assume
address goes down to the 2^24 + 2 * (2^16). that use of IKE will not leak internal address information.
When using an EAP authentication method that does not generate a When using an EAP authentication method that does not generate a
shared key for protecting a subsequent AUTH payload, certain man-in- shared key for protecting a subsequent AUTH payload, certain man-in-
the-middle and server impersonation attacks are possible [EAPMITM]. the-middle and server impersonation attacks are possible [EAPMITM].
These vulnerabilities occur when EAP is also used in protocols which These vulnerabilities occur when EAP is also used in protocols which
are not protected with a secure tunnel. Since EAP is a general- are not protected with a secure tunnel. Since EAP is a general-
purpose authentication protocol, which is often used to provide purpose authentication protocol, which is often used to provide
single-signon facilities, a deployed IPsec solution which relies on single-signon facilities, a deployed IPsec solution which relies on
an EAP authentication method that does not generate a shared key an EAP authentication method that does not generate a shared key
(also known as a non-key-generating EAP method) can become (also known as a non-key-generating EAP method) can become
skipping to change at page 85, line 8 skipping to change at page 86, line 8
authentication exchange, and use it to initiate an IKEv2 connection. authentication exchange, and use it to initiate an IKEv2 connection.
For this reason, use of non-key-generating EAP methods SHOULD be For this reason, use of non-key-generating EAP methods SHOULD be
avoided where possible. Where they are used, it is extremely avoided where possible. Where they are used, it is extremely
important that all usages of these EAP methods SHOULD utilize a important that all usages of these EAP methods SHOULD utilize a
protected tunnel, where the initiator validates the responder's protected tunnel, where the initiator validates the responder's
certificate before initiating the EAP exchange. Implementors SHOULD certificate before initiating the EAP exchange. Implementors SHOULD
describe the vulnerabilities of using non-key-generating EAP methods describe the vulnerabilities of using non-key-generating EAP methods
in the documentation of their implementations so that the in the documentation of their implementations so that the
administrators deploying IPsec solutions are aware of these dangers. administrators deploying IPsec solutions are aware of these dangers.
6 IANA Considerations An implementation using EAP MUST also use a public key based
authentication of the server to the client before the EAP exchange
begins, even if the EAP method offers mutual authentication. This
avoids having additional IKEv2 protocol variations and protects the
EAP data from active attackers.
This document contains many "magic numbers" to be maintained by the 6 IANA Considerations
Internet Assigned Numbers Authority (IANA). While in many cases the
values were chosen so as to avoid collisions with other
specifications, these should be considered a new IANA registry for
IKEv2. The tables to be maintained are:
Payload Types This document defines a number of new field types and values where
Transform Types future assignments will be managed by the IANA. The initial IANA
For each Transform Type defined, the assigned Transform values registry values are documented in [IKEv2IANA].
Authentication Method
Security Protocol ID
Error types
Status types
IPComp Transform IDs
Configuration request types
Configuration attribute types
7 Intellectual Property Rights 7 Intellectual Property Rights
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and IETF's procedures with respect to rights in standards-track and
skipping to change at page 87, line 10 skipping to change at page 88, line 7
"The Addition of Explicit Congestion Notification (ECN) "The Addition of Explicit Congestion Notification (ECN)
to IP", RFC 3168, September 2001. to IP", RFC 3168, September 2001.
[RFC3280] Housley, R., Polk, W., Ford, W., Solo, D., "Internet [RFC3280] Housley, R., Polk, W., Ford, W., Solo, D., "Internet
X.509 Public Key Infrastructure Certificate and X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile", RFC 3280, Certificate Revocation List (CRL) Profile", RFC 3280,
April 2002. April 2002.
9.2 Informative References 9.2 Informative References
[Ble98] Bleichenbacher, D., "Chosen Ciphertext Attacks against
Protocols Based on RSA Encryption Standard PKCS#1",
Advances in Cryptology Eurocrypt '98, Springer-Verlag,
1998.
[BR94] Bellare, M., and Rogaway P., "Optimal Asymmetric
Encryption", Advances in Cryptology Eurocrypt '94,
Springer-Verlag, 1994.
[DES] ANSI X3.106, "American National Standard for Information [DES] ANSI X3.106, "American National Standard for Information
Systems-Data Link Encryption", American National Standards Systems-Data Link Encryption", American National Standards
Institute, 1983. Institute, 1983.
[DH] Diffie, W., and Hellman M., "New Directions in [DH] Diffie, W., and Hellman M., "New Directions in
Cryptography", IEEE Transactions on Information Theory, V. Cryptography", IEEE Transactions on Information Theory, V.
IT-22, n. 6, June 1977. IT-22, n. 6, June 1977.
[DHCP] R. Droms, "Dynamic Host Configuration Protocol", [DHCP] R. Droms, "Dynamic Host Configuration Protocol",
RFC2131 RFC2131
skipping to change at page 87, line 49 skipping to change at page 88, line 37
(IKE)", RFC 2409, November 1998. (IKE)", RFC 2409, November 1998.
[Hutt02] Huttunen, A. et. al., "UDP Encapsulation of IPsec [Hutt02] Huttunen, A. et. al., "UDP Encapsulation of IPsec
Packets", draft-ietf-ipsec-udp-encaps-05.txt, December Packets", draft-ietf-ipsec-udp-encaps-05.txt, December
2002. 2002.
[IDEA] Lai, X., "On the Design and Security of Block Ciphers," [IDEA] Lai, X., "On the Design and Security of Block Ciphers,"
ETH Series in Information Processing, v. 1, Konstanz: ETH Series in Information Processing, v. 1, Konstanz:
Hartung-Gorre Verlag, 1992 Hartung-Gorre Verlag, 1992
[IKEv2IANA]Richardson, M., "Initial IANA registry contents",
draft-ietf-ipsec-ikev2-iana-00.txt, work in progress.
[IPCOMP] Shacham, A., Monsour, R., Pereira, R., and Thomas, M., "IP [IPCOMP] Shacham, A., Monsour, R., Pereira, R., and Thomas, M., "IP
Payload Compression Protocol (IPComp)", RFC 3173, Payload Compression Protocol (IPComp)", RFC 3173,
September 2001. September 2001.
[KPS03] Kaufman, C., Perlman, R., and Sommerfeld, B., "DoS
protection for UDP-based protocols", ACM Conference on
Computer and Communications Security, October 2003.
[Ker01] Keromytis, A., Sommerfeld, B., "The 'Suggested ID' [Ker01] Keromytis, A., Sommerfeld, B., "The 'Suggested ID'
Extension for IKE", draft-keromytis-ike-id-00.txt, 2001 Extension for IKE", draft-keromytis-ike-id-00.txt, 2001
[KBC96] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [KBC96] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, February Hashing for Message Authentication", RFC 2104, February
1997. 1997.
[LDAP] M. Wahl, T. Howes, S. Kille., "Lightweight Directory [LDAP] M. Wahl, T. Howes, S. Kille., "Lightweight Directory
Access Protocol (v3)", RFC2251 Access Protocol (v3)", RFC2251
skipping to change at page 90, line 25 skipping to change at page 91, line 25
with a single four message exchange (with changes in authentication with a single four message exchange (with changes in authentication
mechanisms affecting only a single AUTH payload rather than mechanisms affecting only a single AUTH payload rather than
restructuring the entire exchange); restructuring the entire exchange);
3) To remove the Domain of Interpretation (DOI), Situation (SIT), and 3) To remove the Domain of Interpretation (DOI), Situation (SIT), and
Labeled Domain Identifier fields, and the Commit and Authentication Labeled Domain Identifier fields, and the Commit and Authentication
only bits; only bits;
4) To decrease IKE's latency in the common case by making the initial 4) To decrease IKE's latency in the common case by making the initial
exchange be 2 round trips (4 messages), and allowing the ability to exchange be 2 round trips (4 messages), and allowing the ability to
piggyback setup of a CHILD-SA on that exchange; piggyback setup of a CHILD_SA on that exchange;
5) To replace the cryptographic syntax for protecting the IKE 5) To replace the cryptographic syntax for protecting the IKE
messages themselves with one based closely on ESP to simplify messages themselves with one based closely on ESP to simplify
implementation and security analysis; implementation and security analysis;
6) To reduce the number of possible error states by making the 6) To reduce the number of possible error states by making the
protocol reliable (all messages are acknowledged) and sequenced. This protocol reliable (all messages are acknowledged) and sequenced. This
allows shortening CREATE_CHILD_SA exchanges from 3 messages to 2; allows shortening CREATE_CHILD_SA exchanges from 3 messages to 2;
7) To increase robustness by allowing the responder to not do 7) To increase robustness by allowing the responder to not do
skipping to change at page 98, line 48 skipping to change at page 99, line 48
9) Removed ability to negotiate Diffie-Hellman groups by explicitly 9) Removed ability to negotiate Diffie-Hellman groups by explicitly
passing parameters. They must now be negotiated using Transform IDs. passing parameters. They must now be negotiated using Transform IDs.
10) Renumbered status codes to be contiguous. 10) Renumbered status codes to be contiguous.
11) Specified the meaning of the "Port" fields in Traffic Selectors 11) Specified the meaning of the "Port" fields in Traffic Selectors
when the ICMP protocol is being used. when the ICMP protocol is being used.
12) Removed the specification of D-H Group #5 since it is already 12) Removed the specification of D-H Group #5 since it is already
specified in [ADDGROUP]. specified in [ADDGROUP.
H.10 Changes from IKEv2-09 to IKEv2-10 August 2003 H.10 Changes from IKEv2-09 to IKEv2-10 August 2003
1) Numerous boilerplate and formatting corrections to comply with RFC 1) Numerous boilerplate and formatting corrections to comply with RFC
Editorial Guidelines and procedures. Editorial Guidelines and procedures.
2) Fixed five typographical errors. 2) Fixed five typographical errors.
3) Added a sentence to the end of "Security considerations" 3) Added a sentence to the end of "Security considerations"
discouraging the use of non-key-generating EAP mechanisms. discouraging the use of non-key-generating EAP mechanisms.
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purposes of QoS handling. purposes of QoS handling.
3) Fixed description of ECN handling to make normative references to 3) Fixed description of ECN handling to make normative references to
[RFC 2401bis] and [RFC 3168]. [RFC 2401bis] and [RFC 3168].
4) Fixed two typos in the description of NAT traversal. 4) Fixed two typos in the description of NAT traversal.
5) Added specific ASN.1 encoding of certificate bundles in section 5) Added specific ASN.1 encoding of certificate bundles in section
3.6. 3.6.
H.12 Changes from IKEv2-11 to IKEv2-12 January 2004
1) Made the values of the one byte IPsec Protocol ID consistent
between payloads and made the naming more nearly consistent.
2) Changed the specification to require that AUTH payloads be
provided in EAP exchanges even when a non-key generating EAP method
is used. This protects against certain obscure cryptographic
threats.
3) Changed all example IP addresses to be within subnet 10.
4) Specified that issues surrounding weak keys and DES key parity
must be addressed in algorithm documents.
5) Removed the unsupported (and probably untrue) claim that Photuris
cookies were given that name because the IETF always supports
proposals involving cookies.
6) Fixed some text that specified that Transform ID was 1 octet while
everywhere else said it was 2 octets.
7) Corrected the ASN.1 specification of the encoding of X.509
certificate bundles.
8) Added an INVALID_SELECTORS error type.
9) Replaced IANA considerations section with a reference to draft-
ietf-ipsec-ikev2-iana-00.txt.
10) Removed 2 obsolete informative references and added one to a
paper on UDP fragmentation problems.
11) 41 Editorial Corrections and Clarifications.
12) 6 Grammatical and Spelling errors fixed.
13) 4 Corrected capitalizations of MAY/MUST/etc.
14) 4 Attempts to make capitalization and use of underscores more
consistent.
Editor's Address Editor's Address
Charlie Kaufman Charlie Kaufman
IBM Microsoft Corporation
5 Technology Park Drive 1 Microsoft Way
Westford, MA 01886 Redmond, WA 98052
1-978-399-5000 1-425-707-3335
charlie_kaufman@notesdev.ibm.com charliek@microsoft.com
Full Copyright Statement Full Copyright Statement
"Copyright (C) The Internet Society (2003). All Rights Reserved. "Copyright (C) The Internet Society (2004). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
skipping to change at page 100, line 50 skipping to change at page 102, line 50
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
Acknowledgement Acknowledgement
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
Expiration Expiration
This Internet-Draft (draft-ietf-ipsec-ikev2-10.txt) expires in This Internet-Draft (draft-ietf-ipsec-ikev2-12.txt) expires in July
February 2004. 2004.
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