X.509v3 Certificates for Secure Shell Authentication
RFC 6187

Document Type RFC - Proposed Standard (March 2011; No errata)
Was draft-igoe-secsh-x509v3 (individual in gen area)
Last updated 2013-03-02
Stream IETF
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IESG IESG state RFC 6187 (Proposed Standard)
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Responsible AD spt
Send notices to douglas@stebila.ca, kmigoe@nsa.gov, draft-igoe-secsh-x509v3@ietf.org, jhutz@cmu.edu
Internet Engineering Task Force (IETF)                           K. Igoe
Request for Comments: 6187                      National Security Agency
Category: Standards Track                                     D. Stebila
ISSN: 2070-1721                      Queensland University of Technology
                                                              March 2011

          X.509v3 Certificates for Secure Shell Authentication

Abstract

   X.509 public key certificates use a signature by a trusted
   certification authority to bind a given public key to a given digital
   identity.  This document specifies how to use X.509 version 3 public
   key certificates in public key algorithms in the Secure Shell
   protocol.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6187.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Igoe & Stebila               Standards Track                    [Page 1]
RFC 6187              X.509v3 Certificates for SSH            March 2011

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Public Key Algorithms Using X.509 Version 3 Certificates . . .  4
     2.1.  Public Key Format  . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Certificate Extensions . . . . . . . . . . . . . . . . . .  6
       2.2.1.  KeyUsage . . . . . . . . . . . . . . . . . . . . . . .  7
       2.2.2.  ExtendedKeyUsage . . . . . . . . . . . . . . . . . . .  7
   3.  Signature Encoding . . . . . . . . . . . . . . . . . . . . . .  8
     3.1.  x509v3-ssh-dss . . . . . . . . . . . . . . . . . . . . . .  8
     3.2.  x509v3-ssh-rsa . . . . . . . . . . . . . . . . . . . . . .  8
     3.3.  x509v3-rsa2048-sha256  . . . . . . . . . . . . . . . . . .  9
     3.4.  x509v3-ecdsa-sha2-*  . . . . . . . . . . . . . . . . . . .  9
   4.  Use in Public Key Algorithms . . . . . . . . . . . . . . . . . 10
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Example . . . . . . . . . . . . . . . . . . . . . . . 15
   Appendix B.  Acknowledgements  . . . . . . . . . . . . . . . . . . 15

1.  Introduction

   There are two Secure Shell (SSH) protocols that use public key
   cryptography for authentication.  The Transport Layer Protocol,
   described in [RFC4253], requires that a digital signature algorithm
   (called the "public key algorithm") MUST be used to authenticate the
   server to the client.  Additionally, the User Authentication Protocol
   described in [RFC4252] allows for the use of a digital signature to
   authenticate the client to the server ("publickey" authentication).

   In both cases, the validity of the authentication depends upon the
   strength of the linkage between the public signing key and the
   identity of the signer.  Digital certificates, such as those in X.509
   version 3 (X.509v3) format [RFC5280], are used in many corporate and
   government environments to provide identity management.  They use a
   chain of signatures by a trusted root certification authority and its
   intermediate certificate authorities to bind a given public signing
   key to a given digital identity.

Igoe & Stebila               Standards Track                    [Page 2]
RFC 6187              X.509v3 Certificates for SSH            March 2011
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