INTERNET-DRAFT                                             Markus Friedl
draft-ietf-secsh-fingerprint-01.txt                  The OpenBSD Project
Expires in six months                                     September 2003


                         SSH Fingerprint Format


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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   Distribution of this memo is unlimited.

Abstract

   This document formally documents the fingerprint format in use for
   verifying public keys from SSH clients and servers.

Introduction

   The security of the SSH protocols relies on the verification of
   public host keys.  Since public keys tend to be very large, it is
   difficult for a human to verify an entire host key.  Even with a PKI
   in place, it is useful to have a standard for exchanging short
   fingerprints of public keys.

   This document formally describes the simple key fingerprint format.






Friedl                                                          [Page 1]





INTERNET-DRAFT                                                March 2003


Fingerprint Format

   The fingerprint of a public key consists of the output of the MD5
   message-digest algorithm [RFC-1321].  The input to the algorithm is
   the public key blob as described in [SSH-TRANS].  The output of the
   algorithm is presented to the user as a sequence of 16 octets printed
   as hexadecimal with lowercase letters and separated by colons.

   For example: "c1:b1:30:29:d7:b8:de:6c:97:77:10:d7:46:41:63:87"

References

   [SSH-TRANS] Ylonen, T., et al: "SSH Transport Layer Protocol",
   Internet Draft, draft-secsh-transport-15.txt

   [RFC-1321] R. Rivest: "The MD5 Message-Digest Algorithm", April 1992.

   [RFC-2026] S. Bradner: "The Internet Standards Process -- Revision
   3", October 1996.

Author's  Address:

   Markus Friedl
   markus@openbsd.org
   Munich, Germany


























Friedl                                                          [Page 2]