Browse Prior Art Database

IP Authentication Header (RFC1826) Disclosure Number: IPCOM000004084D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2019-Feb-12
Document File: 13 page(s) / 18K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Atkinson: AUTHOR

Related Documents

10.17487/RFC1826: DOI


This document describes a mechanism for providing cryptographic authentication for IPv4 and IPv6 datagrams. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 11% of the total text.

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.


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.


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 [Page 1]

RFC 1826 IP Authentication Header August 1995

"fragment offset", or "routing pointer") are considered to be zero for the calculation of the authentication data. This provides significantly more security than is currently present in IPv4 and might be sufficient for the needs of many users.

Use of this specification will increase the IP protocol processing costs in participating end systems and will also increase the communications latency. The increased latency is primarily due to the calculation of the authentication data by the sender and the calculation and comparison of the authentication data by the receiver for each IP datagram containing an Authentication Header. The impact will vary with authentication algorithm used and other factors.

In order for the Authentication Header to work properly without changing the entire Internet infrastructure, the authentication data is carried in its own payload. Systems that aren’t p...