Network Working Group P. Saint-Andre
Internet-Draft Cisco Systems, Inc.
Intended status: Informational September 9, 2013
Expires: March 13, 2014
Use of Transport Layer Security (TLS) in the Extensible Messaging and
Presence Protocol (XMPP)
draft-saintandre-xmpp-tls-00
Abstract
This document provides recommendations for the use of Transport Layer
Security (TLS) in the Extensible Messaging and Presence Protocol
(XMPP). This document updates RFC 6120.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
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This Internet-Draft will expire on March 13, 2014.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Discussion Venue . . . . . . . . . . . . . . . . . . . . . . . 3
4. Recommendations . . . . . . . . . . . . . . . . . . . . . . . . 3
4.1. Protocol Versions . . . . . . . . . . . . . . . . . . . . . 3
4.2. Ciphersuites . . . . . . . . . . . . . . . . . . . . . . . 4
5. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
The Extensible Messaging and Presence Protocol (XMPP) [RFC6120]
(along with its precursor, the so-called "Jabber protocol") has used
Transport Layer Security (TLS) [RFC5246] (along with its precursor,
Secure Sockets Layer or SSL) since 1999. Both [RFC6120] and its
predecessor [RFC3920] provided recommendations regarding the use of
TLS in XMPP. Given the evolving threat model on the Internet today
(see, for example, [I-D.trammell-perpass-ppa]), it is necessary to
provide stronger recommendations (see also [I-D.sheffer-tls-bcp]).
This document updates [RFC6120].
2. Terminology
Various security-related terms are to be understood in the sense
defined in [RFC4949].
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
[RFC2119].
3. Discussion Venue
The discussion venue for this document is the mailing list of the
XMPP Working Group, for which archives and subscription information
can be found at <https://www.ietf.org/mailman/listinfo/xmpp>.
4. Recommendations
4.1. Protocol Versions
XMPP implementations MUST NOT negotiate SSL version 2 [RFC6176].
XMPP implementations MUST NOT negotiate SSL version 3.
XMPP implementations MUST support, and prefer to negotiate, TLS
version 1.2 [RFC5246].
XMPP implementations MAY negotiate TLS version 1.1 [RFC4346].
XMPP implementations MAY negotiate TLS version 1.0 [RFC2246].
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4.2. Ciphersuites
XMPP implementations MUST NOT negotiate RC4 ciphersuites
[I-D.popov-tls-prohibiting-rc4].
XMPP implementations MUST NOT negotiate ciphersuites that use so-
called "export-level" encryption (including 40-bit and 56-bit
algorithms).
XMPP implementations MUST NOT negotiate ciphersuites that use less
than 128-bit algorithms.
XMPP implementations SHOULD prefer ciphersuites that use 256-bit
algorithms or higher.
XMPP implementations MUST support, and SHOULD prefer to negotiate,
ciphersuites that offer perfect forward secrecy, such as those in the
"EDH", "DHE", and "ECDH" families.
5. Open Issues
This document has the following open issues:
o Add information about the rationale for each recommendation,
perhaps in an appendix.
o Recommend a specific ciphersuite or a small number of
ciphersuites?
o Provide recommendations regarding key lengths?
o Discuss TLS compression vs. application-layer compression?
6. IANA Considerations
This document requests no actions of the IANA.
7. Security Considerations
This entire document discusses security.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
RFC 4949, August 2007.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, March 2011.
[RFC6176] Turner, S. and T. Polk, "Prohibiting Secure Sockets Layer
(SSL) Version 2.0", RFC 6176, March 2011.
8.2. Informative References
[I-D.popov-tls-prohibiting-rc4]
Popov, A., "Prohibiting RC4 Cipher Suites",
draft-popov-tls-prohibiting-rc4-00 (work in progress),
August 2013.
[I-D.sheffer-tls-bcp]
Sheffer, Y., "Recommendations for Secure Use of TLS and
DTLS", draft-sheffer-tls-bcp-00 (work in progress),
September 2013.
[I-D.trammell-perpass-ppa]
Trammell, B., "The Perfect Passive Adversary: A Threat
Model for the Evaluation of Protocols under Pervasive
Surveillance", draft-trammell-perpass-ppa-00 (work in
progress), September 2013.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999.
[RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 3920, October 2004.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
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Author's Address
Peter Saint-Andre
Cisco Systems, Inc.
1899 Wynkoop Street, Suite 600
Denver, CO 80202
USA
Phone: +1-303-308-3282
Email: psaintan@cisco.com
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