Increase minimum recommended modulus size to 2048 bits
draft-lvelvindron-dh-group-exchange-00

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Last updated 2017-03-10
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Internet Engineering Task Force                       L. Velvindron, Ed.
Internet-Draft                                         Hackers Mauritius
Intended status: Standards Track                          March 10, 2017
Expires: September 11, 2017

         Increase minimum recommended modulus size to 2048 bits
                 draft-lvelvindron-dh-group-exchange-00

Abstract

   The Diffie-Hellman Group Exchange for the Secure Shell (SSH)
   Transport layer Protocol specifies that servers and clients should
   support groups with a modulus length of k bits, where the recommended
   minumum value is 1024 bits.  Recent security research has shown that
   a minimum value of 1024 bits is insufficient against state-sponsored
   actors.  As such, this document formally updates RFC 4419 [RFC4419]
   such that the minimum recommended value for k is 2048 bits and the
   group size is 2048 bits at minimum.

Status of This Memo

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   This Internet-Draft will expire on September 11, 2017.

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   include Simplified BSD License text as described in Section 4.e of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  2048 bits Diffie-Hellman Group  . . . . . . . . . . . . . . .   2
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   4.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Normative References  . . . . . . . . . . . . . . . . . .   3
     4.2.  Informative References  . . . . . . . . . . . . . . . . .   3
     4.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   3

1.  Introduction

   RFC4419 [RFC4419] specifies a recommended minimum size of 1024 for k,
   which is the modulus length of the Diffie-Hellman Group.  It also
   suggests that in all cases, the size of the group needs be at least
   1024 bits.  This document updates RFC 4419 [RFC4419] so that the
   minimum recommended size be 2048 bits

1.1.  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 RFC 2119 [RFC2119].

2.  2048 bits Diffie-Hellman Group

   Recent research [LOGJAM]  [1] strongly suggests that DH groups that
   are 1024 bits can be broken by state actors, and possibly an
   organization with enough computing resources.  The authors show how
   they are able to break 768 bits DH group and extrapolate the attack
   to 1024 bits DH groups.  In their analysis, they show that breaking
   1024 bits can be done with enough computing resources.  This document
   updates section 3 Paragraph 9 : Servers and clients SHOULD support
   groups with a modulus length of k bits where 2048 <= k <= 8192.  The
   recommended minimum values for min and max are 2048 and 8192,
   respectively.  This document also updates Section 3 Paragraph 11: In
   all cases, ths size of the group SHOULD be at least 2048 bits.

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