More Modular Exponential (MODP) Diffie-Hellman (DH) Key Exchange (KEX) Groups for Secure Shell (SSH)
draft-ietf-curdle-ssh-modp-dh-sha2-07

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Last updated 2017-07-30 (latest revision 2017-06-22)
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Internet Engineering Task Force                               M. Baushke
Internet-Draft                                    Juniper Networks, Inc.
Updates: 4250, 4253 (if approved)                          June 22, 2017
Intended status: Standards Track
Expires: December 24, 2017

 More Modular Exponential (MODP) Diffie-Hellman (DH) Key Exchange (KEX)
                     Groups for Secure Shell (SSH)
                 draft-ietf-curdle-ssh-modp-dh-sha2-07

Abstract

   This document defines added Modular Exponential (MODP) Groups for the
   Secure Shell (SSH) protocol using SHA-2 hashes.  This document
   updates RFC 4250.  This document updates RFC 4253.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 24, 2017.

Copyright Notice

   Copyright (c) 2017 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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   described in the Simplified BSD License.

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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

1.  Overview and Rationale

   Secure Shell (SSH) is a common protocol for secure communication on
   the Internet.  Due to recent security concerns with SHA-1 [RFC6194]
   and with MODP groups with less than 2048 bits [NIST-SP-800-131Ar1]
   implementer and users request support for larger Diffie Hellman (DH)
   MODP group sizes with data integrity verification using the SHA-2
   family of secure hash algorithms as well as MODP groups providing
   more security.

   DH primes being adopted by this document are all "safe primes" such
   that p = 2q + 1 where q is also a prime.  New MODP groups are being
   introduced starting with the MODP 3072-bit group 15 all use SHA512 as
   the hash algorithm.

   The DH 2048-bit MODP group 14 is already present in most SSH
   implementations and most implementations already have a SHA256
   implementation, so diffie-hellman-group14-sha256 is provided as easy
   to implement.

   It is intended that these new MODP groups with SHA-2 based hashes
   update the [RFC4253] section 6.4 and [RFC4250] section 4.10
   standards.

   The United States Information Assurance Directorate (IAD) at the
   National Security Agency (NSA) has published "Commercial National
   Security Algorithm (CNSA) Suite and Quantum Computing Frequently
   Asked Questions (FAQ)" [MFQ-U-OO-815099-15] addressed to
   organizations that run classified or unclassified national security
   systems (NSS) and vendors that build products used in NSS.

   This FAQ document indicates that NSS should no longer use:

   o  ECDH and ECDSA with NIST P-256

   o  SHA-256

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   o  AES-128

   o  RSA with 2048-bit keys

   o  Diffie-Hellman with 2048-bit keys
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