< draft-ietf-ipsec-rfc2402bis-10.txt   draft-ietf-ipsec-rfc2402bis-11.txt >
IPsec Working Group S. Kent IPsec Working Group S. Kent
Internet-Draft BBN Technologies Internet-Draft BBN Technologies
draft-ietf-ipsec-rfc2402bis-10.txt December 2004 draft-ietf-ipsec-rfc2402bis-11.txt March 2005
Obsoletes: RFC 2402 Obsoletes: RFC 2402
Expires June 2005 Expires September 2005
IP Authentication Header IP Authentication Header
draft-ietf-ipsec-rfc2402bis-10.txt draft-ietf-ipsec-rfc2402bis-11.txt
Status of This Memo Status of This Memo
By submitting this Internet-Draft, I certify that any applicable By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed, patent or other IPR claims of which I am aware have been disclosed,
and any of which I become aware will be disclosed, in accordance with and any of which I become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
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
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obsoleted by other documents at any time. It is inappropriate to use obsoleted by other documents at any time. It is inappropriate to use
Internet-Drafts as reference material or to cite them other than as a Internet-Drafts as reference material or to cite them other than as a
"work in progress". "work in progress".
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Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Abstract Abstract
This document describes an updated version of the IP Authentication This document describes an updated version of the IP Authentication
Header (AH), which is designed to provide authentication services in Header (AH), which is designed to provide authentication services in
IPv4 and IPv6. This document obsoletes RFC 2402 (November 1998). IPv4 and IPv6. This document obsoletes RFC 2402 (November 1998).
Table of Contents Table of Contents
1. Introduction.......................................................3 1. Introduction.......................................................3
2. Authentication Header Format.......................................4 2. Authentication Header Format.......................................4
2.1 Next Header...................................................5 2.1 Next Header...................................................5
2.2 Payload Length................................................5 2.2 Payload Length................................................5
2.3 Reserved......................................................6 2.3 Reserved......................................................5
2.4 Security Parameters Index (SPI)...............................6 2.4 Security Parameters Index (SPI)...............................6
2.5 Sequence Number...............................................8 2.5 Sequence Number...............................................7
2.5.1 Extended (64-bit) Sequence Number........................8 2.5.1 Extended (64-bit) Sequence Number........................8
2.6 Integrity Check Value (ICV) ..................................9 2.6 Integrity Check Value (ICV) ..................................8
3. Authentication Header Processing...................................9 3. Authentication Header Processing...................................9
3.1 Authentication Header Location...............................9 3.1 Authentication Header Location...............................9
3.1.1 Transport Mode..........................................9 3.1.1 Transport Mode..........................................9
3.1.2 Tunnel Mode............................................10 3.1.2 Tunnel Mode............................................10
3.2 Integrity Algorithms........................................11 3.2 Integrity Algorithms........................................11
3.3 Outbound Packet Processing..................................11 3.3 Outbound Packet Processing..................................11
3.3.1 Security Association Lookup............................11 3.3.1 Security Association Lookup............................11
3.3.2 Sequence Number Generation.............................12 3.3.2 Sequence Number Generation.............................12
3.3.3 Integrity Check Value Calculation......................12 3.3.3 Integrity Check Value Calculation......................13
3.3.3.1 Handling Mutable Fields...........................13 3.3.3.1 Handling Mutable Fields...........................13
3.3.3.1.1 ICV Computation for IPv4.....................13 3.3.3.1.1 ICV Computation for IPv4.....................13
3.3.3.1.1.1 Base Header Fields.......................13 3.3.3.1.1.1 Base Header Fields.......................13
3.3.3.1.1.2 Options..................................14 3.3.3.1.1.2 Options..................................14
3.3.3.1.2 ICV Computation for IPv6.....................14 3.3.3.1.2 ICV Computation for IPv6.....................15
3.3.3.1.2.1 Base Header Fields.......................14 3.3.3.1.2.1 Base Header Fields.......................15
3.3.3.1.2.2 Extension Headers Containing Options.....15 3.3.3.1.2.2 Extension Headers Containing Options.....15
3.3.3.1.2.3 Extension Headers Not Containing Options.15 3.3.3.1.2.3 Extension Headers Not Containing Options.15
3.3.3.2 Padding & Extended Sequence Numbers...............15 3.3.3.2 Padding & Extended Sequence Numbers...............16
3.3.3.2.1 ICV Padding..................................15 3.3.3.2.1 ICV Padding..................................16
3.3.3.2.2 Implicit Packet Padding & ESN................16 3.3.3.2.2 Implicit Packet Padding & ESN................16
3.3.4 Fragmentation..........................................16 3.3.4 Fragmentation..........................................17
3.4 Inbound Packet Processing...................................17 3.4 Inbound Packet Processing...................................17
3.4.1 Reassembly.............................................17 3.4.1 Reassembly.............................................18
3.4.2 Security Association Lookup............................18 3.4.2 Security Association Lookup............................18
3.4.3 Sequence Number Verification...........................18 3.4.3 Sequence Number Verification...........................18
3.4.4 Integrity Check Value Verification.....................20 3.4.4 Integrity Check Value Verification.....................20
4. Auditing..........................................................20 4. Auditing..........................................................21
5. Conformance Requirements..........................................21 5. Conformance Requirements..........................................21
6. Security Considerations...........................................21 6. Security Considerations...........................................21
7. Differences from RFC 2402.........................................21 7. Differences from RFC 2402.........................................22
Acknowledgements.....................................................22 Acknowledgements.....................................................22
References...........................................................22 References...........................................................22
Author Information...................................................22 Author Information...................................................24
Appendix A -- Mutability of IP Options/Extension Headers.............24 Appendix A -- Mutability of IP Options/Extension Headers.............25
A1. IPv4 Options.................................................24 A1. IPv4 Options.................................................25
A2. IPv6 Extension Headers.......................................25 A2. IPv6 Extension Headers.......................................26
Appendix B -- Extended (64-bit) Sequence Numbers.....................27 Appendix B -- Extended (64-bit) Sequence Numbers.....................28
Notices..............................................................33 Notices..............................................................34
1. Introduction 1. Introduction
This document assumes that the reader is familiar with the terms and This document assumes that the reader is familiar with the terms and
concepts described in the "Security Architecture for the Internet concepts described in the "Security Architecture for the Internet
Protocol" [Ken-Arch], hereafter referred to as the Security Protocol" [Ken-Arch], hereafter referred to as the Security
Architecture document. In particular, the reader should be familiar Architecture document. In particular, the reader should be familiar
with the definitions of security services offered by the with the definitions of security services offered by the
Encapsulating Security Payload (ESP) [Ken-ESP]and the IP Encapsulating Security Payload (ESP) [Ken-ESP] and the IP
Authentication Header (AH) [Ken-AH], the concept of Security Authentication Header (AH), the concept of Security Associations, the
Associations, the ways in which ESP can be used in conjunction with ways in which ESP can be used in conjunction with the Authentication
the Authentication Header (AH), and the different key management Header (AH), and the different key management options available for
options available for ESP and AH. ESP and AH.
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in RFC 2119 [Bra97]. document, are to be interpreted as described in RFC 2119 [Bra97].
The IP Authentication Header (AH) is used to provide connectionless The IP Authentication Header (AH) is used to provide connectionless
integrity and data origin authentication for IP datagrams (hereafter integrity and data origin authentication for IP datagrams (hereafter
referred to as just "integrity"), and to provide protection against referred to as just "integrity"), and to provide protection against
replays. This latter, optional service may be selected, by the replays. This latter, optional service may be selected, by the
receiver, when a Security Association is established. (The protocol receiver, when a Security Association is established. (The protocol
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counter and when it reaches the maximum value, the counter rolls over counter and when it reaches the maximum value, the counter rolls over
back to zero. (This behavior is recommended for multi-sender, back to zero. (This behavior is recommended for multi-sender,
multicast SAs, unless anti-replay mechanisms outside the scope of multicast SAs, unless anti-replay mechanisms outside the scope of
this standard are negotiated between the sender and receiver.) this standard are negotiated between the sender and receiver.)
If ESN (see Appendix B) is selected, only the low order 32 bits of If ESN (see Appendix B) is selected, only the low order 32 bits of
the Sequence Number are transmitted in the Sequence Number field, the Sequence Number are transmitted in the Sequence Number field,
although both sender and receiver maintain full 64-bit ESN counters. although both sender and receiver maintain full 64-bit ESN counters.
However, the high order 32 bits are included in the ICV calculation. However, the high order 32 bits are included in the ICV calculation.
Note: If a receiver chooses to not enable anti-replay for an SA, then
the receiver SHOULD NOT negotiate ESN in an SA management protocol.
Use of ESN creates a need for the receiver to manage the anti-replay
window (in order to determine the correct value for the high order
bits of the ESN, which are employed in the ICV computation), which is
generally contrary to the notion of disabling anti-replay for an SA.
3.3.3 Integrity Check Value Calculation 3.3.3 Integrity Check Value Calculation
The AH ICV is computed over: The AH ICV is computed over:
o IP or extension header fields before the AH header that are o IP or extension header fields before the AH header that are
either immutable in transit or that are predictable in value either immutable in transit or that are predictable in value
upon arrival at the endpoint for the AH SA upon arrival at the endpoint for the AH SA
o the AH header (Next Header, Payload Len, Reserved, SPI, o the AH header (Next Header, Payload Len, Reserved, SPI,
Sequence Number (low order 32 bits), and the Integrity Check Sequence Number (low order 32 bits), and the Integrity Check
Value (which is set to zero for this computation), and Value (which is set to zero for this computation), and
explicit padding bytes (if any)) explicit padding bytes (if any))
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Informative Informative
[HC03] Holbrook, H., and Cain, B., "Source Specific Multicast for [HC03] Holbrook, H., and Cain, B., "Source Specific Multicast for
IP", Internet-Draft, draft-ietf-ssm-arch-01.txt, November IP", Internet-Draft, draft-ietf-ssm-arch-01.txt, November
3, 2002. 3, 2002.
[HC98] Harkins, D., and D. Carrel, "The Internet Key Exchange [HC98] Harkins, D., and D. Carrel, "The Internet Key Exchange
(IKE)", RFC 2409, November 1998. (IKE)", RFC 2409, November 1998.
[Ken-AH] Kent, S., "IP Authentication Header (AH)", RFC ???, ???
200?.
[RFC Editor: Please update the reference [Ken-AH] "IP
Authentication Header" (draft-ietf-ipsec-rfc2402bis-10.txt)
with the RFC number and month when it is issued.]
[Ken-ESP] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC [Ken-ESP] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC
???, ???? 200?. ???, ???? 200?.
[RFC Editor: Please update the reference [Ken-ESP] "IP [RFC Editor: Please update the reference [Ken-ESP] "IP
Encapsulating Security Payload (ESP)" (draft-ietf-ipsec- Encapsulating Security Payload (ESP)" (draft-ietf-ipsec-
esp-v3-09.txt) with the RFC number and month when it is esp-v3-09.txt) with the RFC number and month when it is
issued.] issued.]
[NBBB98] Nichols, K., Blake, S., Baker, F., Black, D., "Definition [NBBB98] Nichols, K., Blake, S., Baker, F., Black, D., "Definition
of the Differentiated Services Field (DS Field) in the IPv4 of the Differentiated Services Field (DS Field) in the IPv4
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obtain a general license or permission for the use of such obtain a general license or permission for the use of such
proprietary rights by implementers or users of this specification can proprietary rights by implementers or users of this specification can
be obtained from the IETF Secretariat. be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive this standard. Please address the information to the IETF Executive
Director. Director.
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
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
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revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
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"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
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Expires June 2005 Expires September 2005
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