Deprecating RC4 in Secure Shell (SSH)
draft-ietf-curdle-rc4-die-die-die-15
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8758.
|
|
|---|---|---|---|
| Authors | Luís Câmara , Loganaden Velvindron | ||
| Last updated | 2019-03-27 (Latest revision 2019-01-16) | ||
| Replaces | draft-luis140219-curdle-rc4-die-die-die | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Daniel Migault | ||
| Shepherd write-up | Show Last changed 2018-10-15 | ||
| IESG | IESG state | Became RFC 8758 (Best Current Practice) | |
| Consensus boilerplate | Yes | ||
| Telechat date | (None) | ||
| Responsible AD | Benjamin Kaduk | ||
| Send notices to | Daniel Migault <daniel.migault@ericsson.com> | ||
| IANA | IANA review state | Version Changed - Review Needed |
draft-ietf-curdle-rc4-die-die-die-15
Internet Engineering Task Force L. Camara
Internet-Draft
Obsoletes: 4345 (if approved) L. Velvindron
Intended status: Best Current Practice cyberstorm.mu
Expires: July 20, 2019 January 16, 2019
Deprecating RC4 in Secure Shell (SSH)
draft-ietf-curdle-rc4-die-die-die-15
Abstract
This document deprecates RC4 in Secure Shell (SSH). Therefore, this
document formally obsoletes and moves to Historic RFC4345.
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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Task Force (IETF). Note that other groups may also distribute
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 20, 2019.
Copyright Notice
Copyright (c) 2019 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
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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described in the Simplified BSD License.
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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. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The usage of RC4 suites ( also designated as arcfour ) for SSH are
specified in [RFC4253] and [RFC4345]. [RFC4253] specifies the
allocation of the "arcfour" cipher for SSH. [RFC4345] specifies and
allocates the "arcfour-128" and "arcfour-256" ciphers for SSH. RC4
encryption has known weaknesses [RFC7465]
[I-D.ietf-curdle-des-des-des-die-die-die], and 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 and [RFC4345] is moved to Historic 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", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Updates to RFC 4253
[RFC4253] is updated to prohibit arcfour's use in SSH. [RFC4253]
allocates the "arcfour" cipher in Section 6.3 by defining a list of
defined ciphers where the "arcfour" cipher appears as optional as
mentioned below:
+---------------+-----------------+---------------------------------+
| arcfour | OPTIONAL | the ARCFOUR stream cipher with |
| | | a 128-bit key |
+---------------+-----------------+---------------------------------+
The current document updates the status of the "arcfour" ciphers in
the list of [RFC4253] Section 6.3 by moving it from OPTIONAL to MUST
NOT.
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+----------+-----------+--------------------------------------------+
| arcfour | MUST NOT | the ARCFOUR stream cipher with a 128-bit |
| | | key |
+----------+-----------+--------------------------------------------+
[RFC4253] defines the "arcfour" ciphers with the text mentioned
below:
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 problems with weak keys, and should be used
with caution.
The current document updates [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 weakenesses [RFC7465]
[I-D.ietf-curdle-des-des-des-die-die-die], and MUST NOT be used.
3. IANA Considerations
The IANA is requested to update the Encryption Algorithm Name
Registry of the Secure Shell (SSH) Protocol Parameters [IANA]. The
Registration procedure is IETF Review which is achieved by this
document. The registry should be updated as follows:
+-------------+------------------------------------+
| Encryption | Algorithm Name Reference Note |
+-------------+------------------------------------+
| arcfour | [RFC-TBD] |
| arcfour128 | [RFC-TBD] |
| arcfour256 | [RFC-TBD] |
+-------------+------------------------------------+
Where TBD is the RFC number assigned to the document.
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 introduces no
new security considerations.
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6. References
6.1. 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>.
6.2. Informative References
[I-D.ietf-curdle-des-des-des-die-die-die]
Kaduk, B. and M. Short, "Deprecate 3DES and RC4 in
Kerberos", draft-ietf-curdle-des-des-des-die-die-die-05
(work in progress), September 2017.
[IANA] "Secure Shell (SSH) Protocol Parameters: Encryption
Algorithm Names", <https://www.iana.org/assignments/ssh-
parameters/ssh-parameters.xhtml#ssh-parameters-17>.
[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>.
[SCHNEIER]
Schneier, B., "Applied Cryptography Second Edition:
protocols algorithms and source in code in C", , 1996,
<SCHNEIER>.
Authors' Addresses
Luis Camara
Email: luis.camara@live.com.pt
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Loganaden Velvindron
cyberstorm.mu
Mauritius
Email: loganaden@gmail.com
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