draft-ietf-curdle-rc4-die-die-die-05.txt   draft-ietf-curdle-rc4-die-die-die-06.txt 
Internet Engineering Task Force (IETF) L. Camara Internet Engineering Task Force (IETF) L. Camara
Internet-Draft January 10, 2018 Internet-Draft January 26, 2018
Obsoletes: 4345 Obsoletes: 4345 (if approved)
Updates: 4253 Updates: 4253 (if approved)
Intended Status: Best Current Practice Intended Status: Best Current Practice
Expires: July 14, 2018 Expires: July 30, 2018
Depreciating RC4 in Secure Shell (SSH) Deprecating RC4 in Secure Shell (SSH)
draft-ietf-curdle-rc4-die-die-die-05 draft-ietf-curdle-rc4-die-die-die-06
[[RFC-Editor: please replace the second character of my surname by [[RFC-Editor: please replace the second character of my surname by
U+00E2 when publishing as RFC in the header and in all pages. U+00E2 when publishing as RFC in the header and in all pages.
Non-ASCII characters are allowed in RFCs as per RFC 7997.]] Non-ASCII characters are allowed in RFCs as per RFC 7997.]]
Abstract Abstract
This document depreciates RC4 in Secure Shell (SSH). Therefore, this This document deprecates RC4 in Secure Shell (SSH). Therefore, this
document updates RFC 4253, and formally obsoletes and moves to document updates RFC 4253, and formally obsoletes and moves to
Historic RFC 4345. Historic RFC 4345.
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
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 14, 2018. This Internet-Draft will expire on July 30, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 16 skipping to change at page 2, line 16
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Why obsolete and move to Historic RFC 4345 . . . . . . . . . . 2 2. Why obsolete and move to Historic RFC 4345 . . . . . . . . . . 2
3. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . . 2 3. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 2 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 2
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 3
6. Acknowlegdements . . . . . . . . . . . . . . . . . . . . . . . 3 6. Acknowlegdements . . . . . . . . . . . . . . . . . . . . . . . 3
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 3
7.1. Normative References . . . . . . . . . . . . . . . . . . . . 3 7.1. Normative References . . . . . . . . . . . . . . . . . . . . 3
7.2. Informative References . . . . . . . . . . . . . . . . . . . 3 7.2. Informative References . . . . . . . . . . . . . . . . . . . 3
8. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 4 8. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 3
1. Introduction 1. Introduction
RC4 is extremely weak [RFC6649] [RFC7457] [RFC7465] and this document RC4 is broken [RFC7457] and this document deprecates its use in
depreciates its use in all IETF protocols, including Kerberos and Secure Shell (SSH).
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", 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
BCP 14 [RFC2119, RFC8174] when, and only when, they appear in all BCP 14 [RFC2119, RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Why obsolete and move to Historic RFC 4345 2. Why obsolete and move to Historic RFC 4345
RFC 4345 defines the "arcfour-128" and "arcfour-256" modes for Secure RFC 4345 defines the "arcfour-128" and "arcfour-256" modes for SSH,
Shell (SSH), and is obsoleted and moved to Historic as RC4 is and is obsoleted and moved to Historic as RC4 is broken [RFC7457].
extremely weak [RFC6649, RFC7457] and there is research that is at The modes defined by RFC 4345 MUST NOT be used.
least 5 years old that totally breaks all practical usage of
RC4 [RFC6649].
3. Updates to RFC 4253 3. Updates to RFC 4253
RFC 4253 is updated to note the depreciation of arcfour. RFC 4253 is updated to prohibit arcfour's use in SSH.
The last sentence of the paragraph on RC4 (called "arcfour" The last sentence of the paragraph on RC4 (called "arcfour"
in [RFC4253]) in Section 6.3 of [RFC4253] should read: "Arcfour (and in [RFC4253]) in Section 6.3 of [RFC4253] should read: "Arcfour (also
RC4) are extremely weak [RFC7457] and therefore it MUST NOT be used." known as RC4) is broken [RFC7457] and therefore it MUST NOT be used."
An informative reference to RFC 7457 is to be added to [RFC4253]. An informative reference to RFC 7457 is to be added to [RFC4253].
4. IANA Considerations 4. IANA Considerations
IANA may need to take action as the status for RC4 and 3DES IANA may need to take action as the status for RC4 and 3DES
algorithms for Secure Shell (SSH) is changed by this document algorithms for Secure Shell (SSH) is changed by this document
(see Section 3, that updates [RFC4253]). (see Section 3, that updates [RFC4253]).
5. Security Considerations 5. Security Considerations
This document depreciates RC4, that is obsolete cryptography, and This document only prohibits the use of RC4 in SSH, and introduces no
several attacks that render it useless have been published new security considerations.
published [RFC6649] [RFC7457] [RFC7465].
6. Acknowledgements 6. Acknowledgements
Thanks to the numerous authors which have shown the weaknesses of Thanks to the numerous authors which have shown the weaknesses of
RC4 throughout the years. RC4 throughout the years, and to the several people which have
commented on the CURDLE mailing list about this document.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in
RFC 2119 Key Words", BCP 14, RFC 8174, May 2017. RFC 2119 Key Words", BCP 14, RFC 8174, May 2017.
7.2. Informative References 7.2. Informative References
[RFC4253] Ylonen, T., and C. Lonvick, Ed., "The Secure Shell (SSH) [RFC4253] Ylonen, T., and C. Lonvick, Ed., "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, January 2006. Transport Layer Protocol", RFC 4253, January 2006.
[RFC6151] Turner, S., and L. Chen, "Updated Security Considerations
for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
RFC 6151, March 2011.
[RFC6649] Hornquist Astrand, L. and T. Yu, "Deprecate DES, RC4-HMAC-
EXP, and Other Weak Cryptographic Algorithms in Kerberos",
BCP 179, RFC 6649, July 2012.
[RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing [RFC7457] Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
Known Attacks on Transport Layer Security (TLS) and Known Attacks on Transport Layer Security (TLS) and
Datagram TLS (DTLS)", RFC 7457, February 2015. Datagram TLS (DTLS)", RFC 7457, February 2015.
[RFC7465] Popov, A., "Prohibiting RC4 Cipher Suites", RFC 7465,
February 2015.
[RFCxxxx] Kaduk, B., and M. Short, "Deprecate 3DES and RC4 in
Kerberos", draft-ietf-curdle-des-des-des-die-die-die-05,
Work in Progress.
[[RFC-Editor: please replace the 'i' in my name by U+00ED and the [[RFC-Editor: please replace the 'i' in my name by U+00ED and the
first 'a' in the surname by U+00E2, as non-ASCII characters are first 'a' in the surname by U+00E2, as non-ASCII characters are
allowed as per RFC 7997]] allowed as per RFC 7997]]
11. Author's Address 8. Author's Address
Luis Camara Luis Camara
EMail: <luis.camara@live.com.pt> EMail: <luis.camara@live.com.pt>
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