Depreciating RC4 in Secure Shell (SSH)
draft-ietf-curdle-rc4-die-die-die-05

Document Type Active Internet-Draft (curdle WG)
Last updated 2018-01-10
Replaces draft-luis140219-curdle-rc4-die-die-die
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Internet Engineering Task Force (IETF)                         L. Camara
Internet-Draft                                          January 10, 2018
Obsoletes: 4345
Updates: 4253
Intended Status: Best Current Practice
Expires: July 14, 2018

                 Depreciating RC4 in Secure Shell (SSH)
                  draft-ietf-curdle-rc4-die-die-die-05

[[RFC-Editor: please replace the second character of my surname by
U+00E2 when publishing as RFC in the header and in all pages.
Non-ASCII characters are allowed in RFCs as per RFC 7997.]]

Abstract

   This document depreciates RC4 in Secure Shell (SSH).  Therefore, this
   document updates RFC 4253, and formally obsoletes and moves to
   Historic RFC 4345.

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 July 14, 2018.

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   document authors.  All rights reserved.

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Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2. Why obsolete and move to Historic RFC 4345  . . . . . . . . . .  2
   3. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . .  2
   4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  2
   5. Security Considerations . . . . . . . . . . . . . . . . . . . .  3
   6. Acknowlegdements  . . . . . . . . . . . . . . . . . . . . . . .  3
   7. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   7.1. Normative References  . . . . . . . . . . . . . . . . . . . .  3
   7.2. Informative References  . . . . . . . . . . . . . . . . . . .  3
   8. Author's Address  . . . . . . . . . . . . . . . . . . . . . . .  4

1. Introduction

   RC4 is extremely weak [RFC6649] [RFC7457] [RFC7465] and this document
   depreciates its use in all IETF protocols, including Kerberos and
   Secure Shell (SSH).  The reasons for obsoleting RFC 4345 are
   discussed in Section 2.  The updates to RFC 4253 and the reasons for
   doing them are specified in Section 3.

   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
   BCP 14 [RFC2119, RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2. Why obsolete and move to Historic RFC 4345

   RFC 4345 defines the "arcfour-128" and "arcfour-256" modes for Secure
   Shell (SSH), and is obsoleted and moved to Historic as RC4 is
   extremely weak [RFC6649, RFC7457] and there is research that is at
   least 5 years old that totally breaks all practical usage of
   RC4 [RFC6649].

3. Updates to RFC 4253

   RFC 4253 is updated to note the depreciation of arcfour.

   The last sentence of the paragraph on RC4 (called "arcfour"
   in [RFC4253]) in Section 6.3 of [RFC4253] should read: "Arcfour (and
   RC4) are extremely weak [RFC7457] and therefore it MUST NOT be used."

   An informative reference to RFC 7457 is to be added to [RFC4253].

4. IANA Considerations

   IANA may need to take action as the status for RC4 and 3DES
   algorithms for Secure Shell (SSH) is changed by this document
   (see Section 3, that updates [RFC4253]).

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5. Security Considerations

   This document depreciates RC4, that is obsolete cryptography, and
   several attacks that render it useless have been published
   published [RFC6649] [RFC7457] [RFC7465].
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