RFC 2631 (rfc2631) - Page 1 of 13
Diffie-Hellman Key Agreement Method
Alternative Format: Original Text Document
Network Working Group E. Rescorla
Request for Comments: 2631 RTFM Inc.
Category: Standards Track June 1999
Diffie-Hellman Key Agreement Method
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.
Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
Abstract
This document standardizes one particular Diffie-Hellman variant,
based on the ANSI X9.42 draft, developed by the ANSI X9F1 working
group. Diffie-Hellman is a key agreement algorithm used by two
parties to agree on a shared secret. An algorithm for converting the
shared secret into an arbitrary amount of keying material is
provided. The resulting keying material is used as a symmetric
encryption key. The Diffie-Hellman variant described requires the
recipient to have a certificate, but the originator may have a static
key pair (with the public key placed in a certificate) or an
ephemeral key pair.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Terminology . . . . . . . . . . . . . . . . 2
2. Overview Of Method . . . . . . . . . . . . . . . . . . . . 2
2.1. Key Agreement . . . . . . . . . . . . . . . . . . . . . . 2
2.1.1. Generation of ZZ . . . . . . . . . . . . . . . . . . . 3
2.1.2. Generation of Keying Material . . . . . . . . . . . . . 3
2.1.3. KEK Computation . . . . . . . . . . . . . . . . . . . . 4
2.1.4. Keylengths for common algorithms . . . . . . . . . . . 5
2.1.5. Public Key Validation . . . . . . . . . . . . . . . . . 5
2.1.6. Example 1 . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.7. Example 2 . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Key and Parameter Requirements . . . . . . . . . . . . . 7
2.2.1. Group Parameter Generation . . . . . . . . . . . . . . 7
2.2.1.1. Generation of p, q . . . . . . . . . . . . . . . . . 8
Rescorla Standards Track