wdiff rfc8758.original rfc8758.txt



Internet Engineering Task Force (IETF)                     L. Velvindron
Internet-Draft
Request for Comments: 8758                                 cyberstorm.mu
BCP: 227                                                      April 2020
Updates: 4253 (if approved)                            November 25, 2019
Intended status:
Category: Best Current Practice
Expires: May 28, 2020
ISSN: 2070-1721

                 Deprecating RC4 in Secure Shell (SSH)
                  draft-ietf-curdle-rc4-die-die-die-18

Abstract

   This document deprecates RC4 in Secure Shell (SSH).  Therefore, this
   document formally moves RFC4345 RFC 4345 to historic Historic status.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on May 28, 2020.
   https://www.rfc-editor.org/info/rfc8758.

Copyright Notice

   Copyright (c) 2019 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Acknowledgements
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   The usage of RC4 suites ( also (also designated as arcfour ) "arcfour") for SSH are is
   specified in [RFC4253] and [RFC4345].  [RFC4253] specifies the
   allocation of the "arcfour" cipher for SSH.  [RFC4345] specifies and
   allocates the "arcfour128" and "arcfour256" ciphers for SSH.  RC4
   encryption has known weaknesses [RFC7465] [RFC8429], and [RFC8429]; therefore, this
   document starts the deprecation process should be begun for their use in Secure Shell
   (SSH) [RFC4253].  Accordingly, [RFC4253] is updated to note the
   deprecation of the RC4 ciphers ciphers, and [RFC4345] is moved to Historic
   status, as all ciphers it specifies MUST NOT be used.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]RFC
   8174
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Updates to RFC 4253

   [RFC4253] is updated to prohibit arcfour's use in SSH.  [RFC4253]  [RFC4253],
   Section 6.3 allocates the "arcfour" cipher in Section 6.3 by defining a list of
   defined ciphers where in which the "arcfour" cipher appears as optional optional, as
   mentioned below:

   +---------------+-----------------+---------------------------------+
   shown in Table 1.

   +---------+----------+----------------------------------------------+
   | arcfour | OPTIONAL | the ARCFOUR stream cipher with                    |
   |         |          | with a 128-bit key                           |
   +---------------+-----------------+---------------------------------+
   +---------+----------+----------------------------------------------+

                                  Table 1

   This current document updates the status of the "arcfour" ciphers in the list of [RFC4253]
   found in [RFC4253], Section 6.3 by moving it from OPTIONAL to MUST
   NOT.

   +-----------+-----------+-------------------------------------------+

   +---------+----------+----------------------------------------------+
   | arcfour | MUST NOT | the ARCFOUR stream cipher with a 128-bit                    |
   |         |          | with a 128-bit key                           |
   +-----------+-----------+-------------------------------------------+
   +---------+----------+----------------------------------------------+

                                  Table 2

   [RFC4253] defines the "arcfour" ciphers with the text mentioned
   below: following text:

   |  The "arcfour" cipher is the Arcfour stream cipher with 128-bit
   |  keys.  The Arcfour cipher is believed to be compatible with the
   |  RC4 cipher [SCHNEIER].  Arcfour (and RC4) has problems with weak
   |  keys, and should be used with caution.

   This current document updates [RFC4253] [RFC4253], Section 6.3 by replacing the text
   above with the following text:

   |  The "arcfour" cipher is the Arcfour stream cipher with 128-bit
   |  keys.  The Arcfour cipher is compatible with the RC4 cipher
   |  [SCHNEIER].  Arcfour (and RC4) has known weaknesses [RFC7465] [RFC8429],
   |  [RFC8429] and MUST NOT be used.

3.  IANA Considerations

   The IANA is requested to update has updated the Encryption "Encryption Algorithm Name
   Registry of Names" subregistry in
   the Secure "Secure Shell (SSH) Protocol Parameters Parameters" registry [IANA].  The
   Registration
   registration procedure is IETF Review review, which is achieved by this
   document.  The registry should be has been updated as follows:

        +------------------------------+---------------+---------+

           +---------------------------+-----------+----------+
           | Encryption Algorithm Name | Reference | Note     |
        +------------------------------+---------------+---------+
           +===========================+===========+==========+
           | arcfour                   |  [RFC-TBD] RFC 8758  | HISTORIC |
           +---------------------------+-----------+----------+
           | arcfour128                |    [RFC-TBD] RFC 8758  | HISTORIC |
           +---------------------------+-----------+----------+
           | arcfour256                |    [RFC-TBD] RFC 8758  | HISTORIC |
        +------------------------------+---------------+---------+

   Where TBD is the RFC number assigned to the document.
           +---------------------------+-----------+----------+

                                 Table 3

4.  Acknowledgements

   The authors would like to thank Eric Rescorla, Daniel Migault and
   Rich Salz.

5.  Security Considerations

   This document only prohibits the use of RC4 in SSH, and SSH; it introduces no
   new security considerations.

6.

5.  References

6.1.

5.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

6.2.

5.2.  Informative References

   [IANA]     "Secure Shell (SSH) Protocol Parameters: Encryption
              Algorithm Names", <https://www.iana.org/assignments/ssh-
              parameters/ssh-parameters.xhtml#ssh-parameters-17>. Parameters",
              <https://www.iana.org/assignments/ssh-parameters>.

   [RFC4253]  Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
              January 2006, <https://www.rfc-editor.org/info/rfc4253>.

   [RFC4345]  Harris, B., "Improved Arcfour Modes for the Secure Shell
              (SSH) Transport Layer Protocol", RFC 4345,
              DOI 10.17487/RFC4345, January 2006,
              <https://www.rfc-editor.org/info/rfc4345>.

   [RFC7465]  Popov, A., "Prohibiting RC4 Cipher Suites", RFC 7465,
              DOI 10.17487/RFC7465, February 2015,
              <https://www.rfc-editor.org/info/rfc7465>.

   [RFC8429]  Kaduk, B. and M. Short, "Deprecate Triple-DES (3DES) and
              RC4 in Kerberos", BCP 218, RFC 8429, DOI 10.17487/RFC8429,
              October 2018, <https://www.rfc-editor.org/info/rfc8429>.

   [SCHNEIER] Schneier, B., "Applied Cryptography Second Edition:
              protocols algorithms
              Protocols, Algorithms, and source Source in code Code in C",  , 1996,
              <SCHNEIER>. John
              Wiley and Sons New York, NY, 1996.

Acknowledgements

   The author would like to thank Eric Rescorla, Daniel Migault, and
   Rich Salz.

Author's Address

   Loganaden Velvindron
   cyberstorm.mu
   Mauritius

   Email: logan@cyberstorm.mu