More Modular Exponential (MODP) Diffie-Hellman Groups for SSH
draft-baushke-ssh-dh-group-sha2-01

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Last updated 2015-12-10
Replaced by draft-ietf-curdle-ssh-kex-sha2
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Internet Engineering Task Force                               M. Baushke
Internet-Draft                                    Juniper Networks, Inc.
Updates: 4253 (if approved)                            December 10, 2015
Intended status: Standards Track
Expires: June 12, 2016

     More Modular Exponential (MODP) Diffie-Hellman Groups for SSH
                   draft-baushke-ssh-dh-group-sha2-01

Abstract

   This document defines two added Modular Exponential (MODP) Groups for
   the Secure Shell (SSH) protocol.  It also updates [RFC4253] by
   specifying new RECOMMENDED and new OPTIONAL Diffie-Hellman key
   exchange algorithms using SHA-2 hashes.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on June 12, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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1.  Overview and Rationale

   Secure Shell (SSH) is a common protocol for secure communication on
   the Internet.  In [RFC4253], SSH originally defined the Key Exchange
   Method Name diffie-hellman-group1-sha1 which used [RFC2409] Oakley
   Group 1 (a MODP group with 768 bits) and SHA-1 [RFC3174].  Due to
   recent security concerns with SHA-1 [RFC6194] and with MODP groups
   with less than 2048 bits [NIST-SP-800-131Ar1] implementors and users
   request support for larger MODP group sizes with data integrity
   verification using the SHA-2 family of secure hash algorithms as well
   as MODP groups providing more security.

   Please send comments on this draft to ietf-ssh@NetBSD.org.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  Key Exchange Algorithms

   This memo adopts the style and conventions of [RFC4253] in specifying
   how the use of new data key exchange is indicated in SSH.

   The following new key exchange algorithms are defined:

   Key Exchange Method Name          Note
   diffie-hellman-group1-sha1        NOT RECOMMENDED
   diffie-hellman-group14-sha256     RECOMMENDED
   diffie-hellman-group15-sha256     RECOMMENDED
   diffie-hellman-group16-sha256     OPTIONAL

                                 Figure 1

   The SHA-2 family of secure hash algorithms are defined in
   [FIPS-180-4].

   The method of key exchange used for the name "diffie-hellman-
   group14-sha256" is the same as that for "diffie-hellman-group14-sha1"
   escept that the SHA2-256 hash algorith is used.

   The group15 and group16 names are the same as those specified in
   [RFC3526] as 3072-bit MODP Group 14 and 4096-bit MODP Group 15.

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4.  IANA Considerations

   This document augments the Key Exchange Method Names in [RFC4253].

   IANA is requested to update the SSH algorithm registry with the
   following entries:

   Key Exchange Method Name       Reference   Note
   diffie-hellman-group1-sha1     RFC4253     NOT RECOMMENDED
   diffie-hellman-group14-sha256  This draft  RECOMMENDED
   diffie-hellman-group15-sha256  This draft  RECOMMENDED
   diffie-hellman-group16-sha256  This draft  OPTIONAL

                                 Figure 2

   It is RECOMMENDED that the new diffie-hellman-group14-sha256 method
   be proposed before the diffie-hellman-group14-sha1 method.

5.  Security Considerations

   The security considerations of [RFC4253] apply to this document.

   The security considerations of [RFC3526] suggest that these MODP
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