draft-ietf-curdle-rc4-die-die-die-03.txt   draft-ietf-curdle-rc4-die-die-die-04.txt 
Internet Engineering Task Force (IETF) L. Camara Internet Engineering Task Force (IETF) L. Camara
Internet-Draft December 9, 2017 Internet-Draft December 12, 2017
Obsoletes: 4345 Obsoletes: 4345
Updates: 3501, 4253, 6649, 6733 Updates: 3501, 4253, 6733
Intended Status: Best Current Practice Intended Status: Best Current Practice
Expires: June 12, 2018 Expires: June 15, 2018
Depreciating RC4 in all IETF Protocols Depreciating RC4 in all IETF Protocols
draft-ietf-curdle-rc4-die-die-die-03 draft-ietf-curdle-rc4-die-die-die-04
[[RFC-Editor: Please replace all instances of xxxx in this document with [[RFC-Editor: Please replace all instances of xxxx in this document with
the RFC number of draft-ietf-curdle-des-des-des-die-die-die.]] the RFC number of draft-ietf-curdle-des-des-des-die-die-die.]]
[[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
RC4 is extremely weak as shown by RFC 6649 and RFC 7457, is RC4 is extremely weak as shown by RFC 6649 and RFC 7457, is
prohibited in TLS by RFC 7465, is prohibited in Kerberos by RFC xxxx prohibited in TLS by RFC 7465, is prohibited in Kerberos by RFC xxxx
and it needs to be prohibited in all IETF protocols. This document and it needs to be prohibited in all IETF protocols. This document
obsoletes RFC 4345 "Improved Arcfour Modes for the Secure Shell (SSH) obsoletes RFC 4345 "Improved Arcfour Modes for the Secure Shell (SSH)
Transport Layer Protocol" (note Arcfour and RC4 are synonymous). Transport Layer Protocol" (note Arcfour and RC4 are synonymous).
RFC 3501, RFC 4253, RFC 6649 and RFC 6733 are updated to note the RFC 3501, RFC 4253, RFC 6649 and RFC 6733 are updated to note the
deprecation of RC4 in all IETF protocols. depreciation of RC4 in all IETF protocols.
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 June 12, 2018. This Internet-Draft will expire on June 15, 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
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Why obsolete RFC 4345 . . . . . . . . . . . . . . . . . . . . . 2 2. Why obsolete RFC 4345 . . . . . . . . . . . . . . . . . . . . . 2
3. Updates to RFC 3501 . . . . . . . . . . . . . . . . . . . . . . 3 3. Updates to RFC 3501 . . . . . . . . . . . . . . . . . . . . . . 3
4. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . . 3 4. Updates to RFC 4253 . . . . . . . . . . . . . . . . . . . . . . 3
5. Updates to RFC 6649 . . . . . . . . . . . . . . . . . . . . . . 4 5. Updates to RFC 6733 . . . . . . . . . . . . . . . . . . . . . . 4
6. Updates to RFC 6733 . . . . . . . . . . . . . . . . . . . . . . 4 6. Action to be taken . . . . . . . . . . . . . . . . . . . . . . 4
7. Action to be taken . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 9. Acknowlegdements . . . . . . . . . . . . . . . . . . . . . . . 5
10. Acknowlegdements . . . . . . . . . . . . . . . . . . . . . . . 5 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . . . 5
11.1. Normative References . . . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . . . 6
11.2. Informative References . . . . . . . . . . . . . . . . . . . 6 11. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 6
12. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7 Appendix A. Changelog . . . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Changelog . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
RC4 is extremely weak [RFC6649] [RFC7457] [RFCxxxx] and this document RC4 is extremely weak [RFC6649] [RFC7457] [RFCxxxx] and this document
depreciates its use in all IETF protocols, including Kerberos and depreciates its use in all IETF protocols, including Kerberos and
Secure Shell (SSH). The reasons for obsoleting RFC 4345 are Secure Shell (SSH). The reasons for obsoleting RFC 4345 are
discussed in Section 2. The updates to RFC 3501, RFC 4253, RFC 6649 discussed in Section 2. The updates to RFC 3501, RFC 4253 and
and RFC 6733 and the reasons for doing them are specified in sections RFC 6733 and the reasons for doing them are specified in sections 3,
3, 4, 5 and 6, respectively. 4, and 5, respectively.
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]. BCP 14 [RFC2119, RFC8174].
2. Why obsolete RFC 4345 2. Why obsolete 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 Secure
Shell (SSH), and is moved to Historic as RC4 is extremely Shell (SSH), and is moved to Historic as RC4 is extremely
skipping to change at page 3, line 34 skipping to change at page 3, line 34
were removed in the grounds of security, and all clients and servers were removed in the grounds of security, and all clients and servers
SHOULD comply to [RFC7525]. SHOULD comply to [RFC7525].
""" """
The TLS reference in [RFC3501] should be replaced with a reference to The TLS reference in [RFC3501] should be replaced with a reference to
RFC 5246, and references to RFC 6151, RFC 6649, RFC 7457, RFC 7465, RFC 5246, and references to RFC 6151, RFC 6649, RFC 7457, RFC 7465,
RFC xxxx and this document (as RFC yyyy) should be added. RFC xxxx and this document (as RFC yyyy) should be added.
4. Updates to RFC 4253 4. Updates to RFC 4253
RFC 4253 is updated to note the deprecation of arcfour and 3des-cbc. RFC 4253 is updated to note the depreciation of arcfour and 3des-cbc.
This document changes "OPTIONAL" to "NOT RECOMMENDED" for arcfour and This document changes "OPTIONAL" to "NOT RECOMMENDED" for arcfour and
"REQUIRED" to "OPTIONAL" for 3des-cbc in the table of "REQUIRED" to "OPTIONAL" for 3des-cbc in the table of
Section 6.3 of [RFC4253] as 3DES is weak and maintaining the Section 6.3 of [RFC4253] as 3DES is weak and maintaining the
requirement will compromise systems. [RFC4253] was published in requirement will compromise systems. [RFC4253] was published in
2006, 11 years ago, and states that """At some future time, it is 2006, 11 years ago, and states that """At some future time, it is
expected that another algorithm, one with better strength, will expected that another algorithm, one with better strength, will
become so prevalent and ubiquitous that the use of "3des-cbc" will be become so prevalent and ubiquitous that the use of "3des-cbc" will be
deprecated by another STANDARDS ACTION.""" deprecated by another STANDARDS ACTION."""
skipping to change at page 4, line 8 skipping to change at page 4, line 8
AES is ubiquitous in Kerberos implementations (see Section 11). AES is ubiquitous in Kerberos implementations (see Section 11).
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 (and
RC4) are extremely weak [RFC6649] [RFC7457] [RFCxxxx] [RFCyyyy] and RC4) are extremely weak [RFC6649] [RFC7457] [RFCxxxx] [RFCyyyy] and
therefore their use is NOT RECOMMENDED." therefore their use is NOT RECOMMENDED."
References to RFC 6649, RFC 7457, RFC xxxx and this document (the References to RFC 6649, RFC 7457, RFC xxxx and this document (the
reference to this document is RFCyyyy in the above paragraph) should reference to this document is RFCyyyy in the above paragraph) should
be added to Section 6.3 of [RFC4253]. be added to Section 6.3 of [RFC4253].
5. Updates to RFC 6649 5. Updates to RFC 6733
RFC 6649, also known as BCP 179, depreciates DES, RC4-HMAC-EXP and
other weak cryptography in Kerberos. It is updated to note the
deprecation of rc4-hmac and the deprecation of RC4 in all IETF
protocols.
The security considerations of [RFC6649] (Section 6 of [RFC6649])
read, in their last paragraph:
"""
The security considerations of [RFC4757] continue to apply to
RC4-HMAC, including the known weaknesses of RC4 and MD4, and this
document does not change the Informational status of [RFC4757] for
now. The main reason to not actively discourage the use of RC4-HMAC
is that it is the only encryption type that interoperates with older
versions of Microsoft Windows once DES and RC4-HMAC-EXP are removed.
These older versions of Microsoft Windows will likely be in use until
at least 2015.
"""
This is updated to note that Windows XP is without official support
for 3 years (support for Windows XP ended 8 April 2014).
6. Updates to RFC 6733
Section 13.1 of [RFC6733] required that clients implement two RC4 Section 13.1 of [RFC6733] required that clients implement two RC4
cipher suites and a 3DES cipher suite (but recommends implementing an cipher suites and a 3DES cipher suite (but recommends implementing an
AES cipher suite). AES cipher suite).
RFC 6733 was published in October 2012, and all paragraphs but the RFC 6733 was published in October 2012, and all paragraphs but the
last of Section 13.1 of [RFC6733] are to be replaced with: last of Section 13.1 of [RFC6733] are to be replaced with:
""" """
Diameter nodes were formerly required to implement insecure RC4 Diameter nodes were formerly required to implement insecure RC4
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Diameter nodes MUST comply to [RFC7525]. Diameter nodes MUST comply to [RFC7525].
TLS_RSA_WITH_AES_128_CBC_SHA was not chosen to be absolutely required TLS_RSA_WITH_AES_128_CBC_SHA was not chosen to be absolutely required
as Diameter nodes may require all connections to use forward secrecy as Diameter nodes may require all connections to use forward secrecy
by only implementing cipher suites with forward secrecy. by only implementing cipher suites with forward secrecy.
TLS_RSA_WITH_AES_128_CBC_SHA is not a forward secrecy cipher suite TLS_RSA_WITH_AES_128_CBC_SHA is not a forward secrecy cipher suite
because all connections can be decrypted once the private RSA key is because all connections can be decrypted once the private RSA key is
known by an attacker. known by an attacker.
""" """
7. Action to be taken 6. Action to be taken
RC4 MUST NOT be used in new implementations of IETF protocols, and RC4 MUST NOT be used in new implementations of IETF protocols, and
RC4 MUST be eliminated as fast as possible from the existing Internet RC4 MUST be eliminated as fast as possible from the existing Internet
infrastructure, as RC4 is insecure [RFC6649] [RFC7457] [RFCxxxx]. infrastructure, as RC4 is insecure [RFC6649] [RFC7457] [RFCxxxx].
Vendors SHOULD take action to eradicate RC4 in all their software Vendors SHOULD take action to eradicate RC4 in all their software
and systems. and systems.
New IETF protocols MUST NOT allow RC4, and new versions of existing New IETF protocols MUST NOT allow RC4, and new versions of existing
IETF protocols MUST either not allow RC4 or recommend not to use RC4 IETF protocols MUST either not allow RC4 or recommend not to use RC4
(for example, using "NOT RECOMMENDED" or "SHOULD NOT"). (for example, using "NOT RECOMMENDED" or "SHOULD NOT").
8. IANA Considerations 7. 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 6, that updates [RFC4253]). (see Section 4, that updates [RFC4253]).
9. Security Considerations 8. Security Considerations
This document depreciates RC4, that is obsolete cryptography, and This document depreciates RC4, that is obsolete cryptography, and
several attacks that render it useless have been published [RFC6649]. several attacks that render it useless have been published [RFC6649].
Refer to Section 5 of [RFCxxxx] for further security considerations. Refer to Section 5 of [RFCxxxx] for further security considerations.
10. Acknowledgements 9. Acknowledgements
[[RFC-Editor: When possible, add native names according to the [[RFC-Editor: When possible, add native names according to the
conventions of RFC 7997.]] conventions of RFC 7997.]]
Thanks to the following people: Thanks to the following people:
* Sean Turner and Lily Chen for writing RFC 6151, that contains * Sean Turner and Lily Chen for writing RFC 6151, that contains
updated security considerations for MD5 and HMAC-MD5. updated security considerations for MD5 and HMAC-MD5.
* Love Hornquist Astrand and Tom Yu for writing RFC 6649, that * Love Hornquist Astrand and Tom Yu for writing RFC 6649, that
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* Andrei Popov for writing RFC 7465, that prohibits RC4 cipher * Andrei Popov for writing RFC 7465, that prohibits RC4 cipher
suites in Transport Layer Security (TLS). suites in Transport Layer Security (TLS).
* Julien Elie for sending me an email about the requirements to * Julien Elie for sending me an email about the requirements to
implement RC4 cipher suites in RFC 3501 and RFC 6733. implement RC4 cipher suites in RFC 3501 and RFC 6733.
Refer to the acknowledgements section of RFC 6649, RFC 7457 and Refer to the acknowledgements section of RFC 6649, RFC 7457 and
RFC xxxx for further acknowledgements. RFC xxxx for further acknowledgements.
11. References 10. References
11.1. Normative References 10.1. 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.
[RFC6649] Hornquist Astrand, L. and T. Yu, "Deprecate DES, RC4-HMAC- [RFC6649] Hornquist Astrand, L. and T. Yu, "Deprecate DES, RC4-HMAC-
EXP, and Other Weak Cryptographic Algorithms in Kerberos", EXP, and Other Weak Cryptographic Algorithms in Kerberos",
BCP 179, RFC 6649, July 2012. BCP 179, RFC 6649, July 2012.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, May 2015. (DTLS)", BCP 195, RFC 7525, May 2015.
[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.
[RFCxxxx] Kaduk, B., and M. Short, "Deprecate 3DES and RC4 in [RFCxxxx] Kaduk, B., and M. Short, "Deprecate 3DES and RC4 in
Kerberos", draft-ietf-curdle-des-des-des-die-die-die-05, Kerberos", draft-ietf-curdle-des-des-des-die-die-die-05,
Work in Progress. Work in Progress.
11.2. Informative References 10.2. Informative References
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - Version [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - Version
4rev1", RFC 3501, March 2003. 4rev1", RFC 3501, March 2003.
[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.
[RFC4757] Jaganathan, K., Zhu, L., and J. Brezak, "The RC4-HMAC [RFC4757] Jaganathan, K., Zhu, L., and J. Brezak, "The RC4-HMAC
Kerberos Encryption Types Used by Microsoft Windows", Kerberos Encryption Types Used by Microsoft Windows",
RFC 4757, December 2006. RFC 4757, December 2006.
skipping to change at page 7, line 9 skipping to change at page 6, line 39
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, [RFC7465] Popov, A., "Prohibiting RC4 Cipher Suites", RFC 7465,
February 2015. February 2015.
[[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]]
12. Author's Address 11. Author's Address
Luis Camara Luis Camara
EMail: <luis.camara@live.com.pt> EMail: <luis.camara@live.com.pt>
Appendix A. Changelog Appendix A. Changelog
[[RFC-Editor: please remove this section when publishing.]] [[RFC-Editor: please remove this section when publishing.]]
WG draft: WG draft:
04 - Removed the updates to RFC 6649 per the mailing list comments.
03 - Style changes, removed SSL Labs paragraph in the 03 - Style changes, removed SSL Labs paragraph in the
acknowledgements section and updated RFCxxxx reference to v05. acknowledgements section and updated RFCxxxx reference to v05.
Now British English is used in all parts of the document, Now British English is used in all parts of the document,
except quotations. except quotations.
02 - Addressed Todd Short's concerns. 02 - Addressed Todd Short's concerns.
01 - Massive simplification: removed informational updates, removed 01 - Massive simplification: removed informational updates, removed
all Pre-5378 Material, retracted all "Obsoletes:" except for all Pre-5378 Material, retracted all "Obsoletes:" except for
RFC 4345, removed Appendix A and renamed changelog to Appendix A. RFC 4345, removed Appendix A and renamed changelog to Appendix A.
 End of changes. 20 change blocks. 
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