draft-ietf-curdle-rc4-die-die-die-07.txt   draft-ietf-curdle-rc4-die-die-die-08.txt 
Internet Engineering Task Force (IETF) L. Camara
Internet-Draft L.Velvindron
Obsoletes: 4345 (if approved) July 22, 2018
Updates: 4253 (if approved)
Intended Status: Best Current Practice
Expires: July 22, 2018
Deprecating RC4 in Secure Shell (SSH) Internet Engineering Task Force L. Camara
draft-ietf-curdle-rc4-die-die-die-07 Internet-Draft
Obsoletes: 4325 (if approved) L. Velvindron
Updates: 4253 (if approved) August 9, 2018
Intended status: Best Current Practice
Expires: February 10, 2019
[[RFC-Editor: please replace the second character of my surname by Deprecating RC4 in Secure Shell (SSH)
U+00E2 when publishing as RFC in the header and in all pages.]] draft-ietf-curdle-rc4-die-die-die-08
Abstract Abstract
This document deprecates RC4 in Secure Shell (SSH). Therefore, this This document deprecates RC4 in Secure Shell (SSH). Therefore, this
document updates RFC 4253, and moves to Historic RFC 4345. document updates [RFC4253], and formally obsoletes and moves to
Historic [RFC4345].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on July 30, 2018. This Internet-Draft will expire on February 10, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Why obsolete and move to Historic RFC 4345 . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
3. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . . 2 2. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 2 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 3 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. Acknowlegdements . . . . . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . . . 3 6.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . . . 3 6.2. Informative References . . . . . . . . . . . . . . . . . 4
8. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 3 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
The usage of RC4 suites ( also designated as arcfour ) for SSH are The usage of RC4 suites ( also designated as arcfour ) for SSH are
specified in [RFC 4253] and [RFC 4345]. [RFC 4253] specifies the specified in [RFC4253] and [RFC4345]. [RFC4253] specifies the
allocation of the "arcfour" cipher for SSH. RFC 4345 specifies and allocation of the "arcfour" cipher for SSH. [RFC4345] specifies and
allocates the the "arcfour-128" and "arcfour-256" ciphers for SSH. allocates the the "arcfour-128" and "arcfour-256" ciphers for SSH.
RC4 encryption is steadily weakening in cryptographic strength
[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.
RC4 encryption is steadily weakening in cryptographic strength [RFC7457] 1.1. Requirements Language
[draft-ietf-curdle-des-des-des-die-die-die-05] and the deprecation process
should be begun for their use in SSH.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in document are to be interpreted as described in RFC 2119 [RFC2119].
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 2. Updates to RFC 4253
RFC 4345 defines the "arcfour-128" and "arcfour-256" modes for SSH, [RFC4253] is updated to prohibit arcfour's use in SSH. [RFC4253]
and is obsoleted and moved to Historic as RC4 is broken [RFC7457]. allocates the "arcfour" cipher in Section 6.3 by defining a list of
The modes defined by RFC 4345 MUST NOT be used. defined ciphers where the "arcfour" cipher appears as optional as
mentioned below:
3. Updates to RFC 4253 +---------------+-----------------+---------------------------------+
| arcfour | OPTIONAL | the ARCFOUR stream cipher with |
| | | a 128-bit key |
+---------------+-----------------+---------------------------------+
RFC 4253 is updated to prohibit arcfour's use in SSH. 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.
The last sentence of the paragraph on RC4 (called "arcfour" +----------+-----------+--------------------------------------------+
in [RFC4253]) in Section 6.3 of [RFC4253] should read: "Arcfour (also | arcfour | MUST NOT | the ARCFOUR stream cipher with a 128-bit |
known as RC4) is broken [RFC7457] and therefore it MUST NOT be used." | | | key |
+----------+-----------+--------------------------------------------+
An informative reference to RFC 7457 is to be added to [RFC4253]. [RFC4253] defines the "arcfour" ciphers with the text mentioned
below:
4. IANA Considerations 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.
IANA may need to take action as the status for RC4 and 3DES The current document updates [RFC4253] Section 6.3 by replacing the
algorithms for Secure Shell (SSH) is changed by this document text above with the following text:
(see Section 3, that updates [RFC4253]).
5. Security Considerations 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) is steadily weakening in cryptographic
strength [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.
All drafts are required to have an IANA considerations section (see
Guidelines for Writing an IANA Considerations Section in RFCs
[RFC5226] for a guide). If the draft does not require IANA to do
anything, the section contains an explicit statement that this is the
case (as above). If there are no requirements for IANA, the section
will be removed during conversion into an RFC by the RFC Editor.
4. Acknowledgements
The authors would like to thank Daniel Migault
5. Security Considerations
This document only prohibits the use of RC4 in SSH, and introduces no This document only prohibits the use of RC4 in SSH, and introduces no
new security considerations. new security considerations.
6. Acknowledgements 6. References
Thanks to the numerous authors which have shown the weaknesses of 6.1. Normative References
RC4 throughout the years, and to the several people which have
commented on the CURDLE mailing list about this document.
7. 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>.
7.1. Normative References [SCHNEIER]
Schneier, B., "Applied Cryptography Second Edition:
protocols algorithms and source in code in C", , 1996,
<SCHNEIER>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6.2. Informative References
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in [I-D.ietf-curdle-des-des-des-die-die-die]
RFC 2119 Key Words", BCP 14, RFC 8174, May 2017. 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.
7.2. Informative References [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>.
[RFC4253] Ylonen, T., and C. Lonvick, Ed., "The Secure Shell (SSH) [RFC4345] Harris, B., "Improved Arcfour Modes for the Secure Shell
Transport Layer Protocol", RFC 4253, January 2006. (SSH) Transport Layer Protocol", RFC 4345,
DOI 10.17487/RFC4345, January 2006,
<https://www.rfc-editor.org/info/rfc4345>.
[RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
Known Attacks on Transport Layer Security (TLS) and IANA Considerations Section in RFCs", RFC 5226,
Datagram TLS (DTLS)", RFC 7457, February 2015. DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[[RFC-Editor: please replace the 'i' in my name by U+00ED and the [RFC7465] Popov, A., "Prohibiting RC4 Cipher Suites", RFC 7465,
first 'a' in the surname by U+00E2, as non-ASCII characters are DOI 10.17487/RFC7465, February 2015,
allowed as per RFC 7997]] <https://www.rfc-editor.org/info/rfc7465>.
8. Author's Address Authors' Addresses
Luis Camara Luis Camara
EMail: <luis.camara@live.com.pt> Email: luis.camara@live.com.pt
Loganaden Velvindron Loganaden Velvindron
Mauritius
EMail: <loganaden@gmail.com> Email: logan@hackers.mu
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