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 provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on March 13, 2014.

Copyright Notice

Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Introduction
• 2. Terminology
• 3. Discussion Venue
• 4. Recommendations
• 4.1. Protocol Versions
• 4.2. Ciphersuites
• 5. Open Issues
• 6. IANA Considerations
• 7. Security Considerations
• 8. References
• 8.1. Normative References
• 8.2. Informative References
• Author's Address

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].

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:

• Add information about the rationale for each recommendation, perhaps in an appendix.
• Recommend a specific ciphersuite or a small number of ciphersuites?
• Provide recommendations regarding key lengths?
• 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

8.2. Informative References

Author's Address