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The ESP DES-CBC Transform (RFC1829)

IP.com Disclosure Number: IPCOM000004087D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2019-Feb-12
Document File: 11 page(s) / 13K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

P. Karn: AUTHOR [+2]

Related Documents

10.17487/RFC1829: DOI

Abstract

This document describes the DES-CBC security transform for the IP Encapsulating Security Payload (ESP). [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 20% of the total text.

Network Working Group P. Karn Request for Comments: 1829 Qualcomm Category: Standards Track P. Metzger Piermont W. Simpson Daydreamer August 1995

The ESP DES-CBC Transform

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 the DES-CBC security transform for the IP Encapsulating Security Payload (ESP).

Table of Contents

1. Introduction .......................................... 1 1.1 Keys ............................................ 1 1.2 Initialization Vector ........................... 1 1.3 Data Size ....................................... 2 1.4 Performance ..................................... 2

2. Payload Format ........................................ 3

3. Algorithm ............................................. 5 3.1 Encryption ...................................... 5 3.2 Decryption ...................................... 5

SECURITY CONSIDERATIONS ...................................... 6 ACKNOWLEDGEMENTS ............................................. 7 REFERENCES ................................................... 8 AUTHOR’S ADDRESS ............................................. 10

Karn, Metzger & Simpson Standards Track [Page i]

RFC 1829 ESP DES-CBC August 1995

1. Introduction

The Encapsulating Security Payload (ESP) [RFC-1827] provides confidentiality for IP datagrams by encrypting the payload data to be protected. This specification describes the ESP use of the Cipher Block Chaining (CBC) mode of the US Data Encryption Standard (DES) algorithm [FIPS-46, FIPS-46-1, FIPS-74, FIPS-81].

All implementations that claim conformance or compliance with the Encapsulating Security Payload specification MUST implement this DES-CBC transform.

This document assumes that the reader is familiar with the related document "Security Architecture for the Internet Protocol" [RFC-1825], which defines the overall security plan for IP, and provides important background for this specification.

1.1. Keys

The secret DES key shared between the communicating parties is eight octets in length. This key consists of a 56-bit quantity used by the DES algorithm. The 56-bit key is stored as a 64-bit (eight octet) quantity, with the least significant bit of each octet used as a parity bit.

1.2. Initialization Vector

This mode of DES requires an Initialization Vector (IV) that is eight octets in length.

Each datagram contains its own IV. Including the IV in each datagram ensures that decryption of each received datagram can be performed, even when other datagrams are dropped, or datagrams are re-ordered in transit.

The method for selection of IV values is implementation dependent.

Notes: A common acceptable technique is simply a counter, begi...

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