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HMAC-MD5 IP Authentication with Replay Prevention (RFC2085)

IP.com Disclosure Number: IPCOM000002637D
Original Publication Date: 1997-Feb-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 5 page(s) / 13K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Oehler: AUTHOR [+2]

Abstract

This document describes a keyed-MD5 transform to be used in conjunction with the IP Authentication Header [RFC-1826]. The particular transform is based on [HMAC-MD5]. An option is also specified to guard against replay attacks.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 24% of the total text.

Network Working Group M. Oehler

Request for Comments: 2085 NSA

Category: Standards Track R. Glenn

NIST

February 1997

HMAC-MD5 IP Authentication with Replay Prevention

Status of This Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Abstract

This document describes a keyed-MD5 transform to be used in

conjunction with the IP Authentication Header [RFC-1826]. The

particular transform is based on [HMAC-MD5]. An option is also

specified to guard against replay attacks.

Table of Contents

1. Introduction...................................................1

1.1 Terminology.................................................2

1.2 Keys........................................................2

1.3 Data Size...................................................3

2. Packet Format..................................................3

2.1 Replay Prevention...........................................4

2.2 Authentication Data Calculation.............................4

3. Security Considerations........................................5

Acknowledgments....................................................5

References.........................................................6

Authors' Addresses.................................................6

1. Introduction

The Authentication Header (AH) [RFC-1826] provides integrity and

authentication for IP datagrams. The transform specified in this

document uses a keyed-MD5 mechanism [HMAC-MD5]. The mechanism uses

the (key-less) MD5 hash function [RFC-1321] which produces a message

digest. When combined with an AH Key, authentication data is

produced. This value is placed in the Authentication Data field of

the AH [RFC-1826]. This value is also the basis for the data

integrity service offered by the AH protocol.

To provide protection against replay attacks, a Replay Prevention

field is included as a transform option. This field is used to help

prevent attacks in which a message is stored and re-used later,

replacing or repeating the original. The Security Parameters Index

(SPI) [RFC-1825] is used to determine whether this option is included

in the AH.

Familiarity with the following documents is assumed: "Security

Architecture for the Internet Protocol" [RFC-1825], "IP

Authentication Header" [RFC-1826], and "HMAC-MD5: Keyed-MD5 for

Message Authentication" [HMAC-MD5].

All implementations that claim conformance or compli...