GSS-API Key Exchange with SHA2
draft-ssorce-gss-keyex-sha2-00

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Last updated 2016-12-13
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Internet Engineering Task Force                                 S. Sorce
Internet-Draft                                                  H. Kario
Updates: 4462 (if approved)                                Red Hat, Inc.
Intended status: Standards Track                       December 13, 2016
Expires: June 16, 2017

                     GSS-API Key Exchange with SHA2
                     draft-ssorce-gss-keyex-sha2-00

Abstract

   This document specifies additions and amendments to SSH GSS-API
   Methods [RFC4462].  It defines a new key exchange method that uses
   SHA-2 for integrity and deprecates weak DH groups.  The purpose of
   this specification is to modernize the cryptographic primitives used
   by GSS Key Exchanges.

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 16, 2017.

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   Copyright (c) 2016 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
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   include Simplified BSD License text as described in Section 4.e of

Sorce & Kario             Expires June 16, 2017                 [Page 1]
Internet-Draft               GSS Keyex SHA2                December 2016

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Rationale . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Document Conventions  . . . . . . . . . . . . . . . . . . . .   2
   4.  New Diffie-Hellman Key Exchange methods . . . . . . . . . . .   3
     4.1.  gss-group14-sha256-*  . . . . . . . . . . . . . . . . . .   3
     4.2.  gss-group15-sha512-*  . . . . . . . . . . . . . . . . . .   3
     4.3.  gss-group16-sha512-*  . . . . . . . . . . . . . . . . . .   3
     4.4.  gss-group17-sha512-*  . . . . . . . . . . . . . . . . . .   4
     4.5.  gss-group18-sha512-*  . . . . . . . . . . . . . . . . . .   4
   5.  New Elliptic Curve Diffie-Hellman Key Exchange methods  . . .   4
     5.1.  Generic GSS-API Key Exchange with ECDH  . . . . . . . . .   4
     5.2.  ECDH Key Exchange Methods . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     7.1.  New Finite Field DH mechanisms  . . . . . . . . . . . . .  10
     7.2.  New Elliptic Curve DH mechanisms  . . . . . . . . . . . .  10
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   SSH GSS-API Methods [RFC4462] allows the use of GSSAPI for
   authentication and key exchange in SSH.  It defines three exchange
   methods all based on DH groups and SHA-1.  The new methods described
   in this document are intended to support environments that desired to
   use the SHA-2 cryptographic hash functions.

2.  Rationale

   Due to security concerns with SHA-1 [RFC6194] and with MODP groups
   with less than 2048 bits [NIST-SP-800-131Ar1] we propose the use of
   the SHA-2 based hashes with DH group14, group15, group16, group17 and
   group18 [RFC3526].  Additionally we add support for key exchange
   based on Elliptic Curve Diffie Hellman with NIST P-256, P-384 and
   P-521 as well as X25519 and X448 curves.  Following the rationale of
   [I-D.ietf-curdle-ssh-kex-sha2] only SHA-256 and SHA-512 hashes are
   used.

3.  Document Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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