RFC 1826 (rfc1826) - Page 1 of 13

IP Authentication Header

Network Working Group                                        R. Atkinson
Request for Comments: 1826                     Naval Research Laboratory
Category: Standards Track                                    August 1995


                        IP Authentication Header

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 mechanism for providing cryptographic
   authentication for IPv4 and IPv6 datagrams.  An Authentication Header
   (AH) is normally inserted after an IP header and before the other
   information being authenticated.

1. INTRODUCTION

   The Authentication Header is a mechanism for providing strong
   integrity and authentication for IP datagrams.  It might also provide
   non-repudiation, depending on which cryptographic algorithm is used
   and how keying is performed.  For example, use of an asymmetric
   digital signature algorithm, such as RSA, could provide non-
   repudiation.

   Confidentiality, and protection from traffic analysis are not
   provided by the Authentication Header.  Users desiring
   confidentiality should consider using the IP Encapsulating Security
   Protocol (ESP) either in lieu of or in conjunction with the
   Authentication Header [Atk95b].  This document assumes the reader has
   previously read the related IP Security Architecture document which
   defines the overall security architecture for IP and provides
   important background information for this specification [Atk95a].

1.1 Overview

   The IP Authentication Header seeks to provide security by adding
   authentication information to an IP datagram. This authentication
   information is calculated using all of the fields in the IP datagram
   (including not only the IP Header but also other headers and the user
   data) which do not change in transit.  Fields or options which need
   to change in transit (e.g., "hop count", "time to live", "ident",



Atkinson                    Standards Track