draft-ietf-mmusic-4572-update-00.txt   draft-ietf-mmusic-4572-update-01.txt 
Network Working Group C. Holmberg Network Working Group C. Holmberg
Internet-Draft Ericsson Internet-Draft Ericsson
Updates: 4572 (if approved) May 4, 2016 Updates: 4572 (if approved) May 5, 2016
Intended status: Standards Track Intended status: Standards Track
Expires: November 5, 2016 Expires: November 6, 2016
Updates to RFC 4572 Updates to RFC 4572
draft-ietf-mmusic-4572-update-00.txt draft-ietf-mmusic-4572-update-01.txt
Abstract Abstract
This document updates RFC 4572 by clarifying the usage of multiple This document updates RFC 4572 by clarifying the usage of multiple
SDP 'fingerprint' attributes with a single TLS connection. The SDP 'fingerprint' attributes with a single TLS connection. The
document also updates the preferred cipher suite to be used, and document also updates the preferred cipher suite to be used, and
removes the requirement to use the same hash function for calculating removes the requirement to use the same hash function for calculating
the certificate fingerprint that is used to calculate the certificate the certificate fingerprint that is used to calculate the certificate
signature. signature.
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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 November 5, 2016. This Internet-Draft will expire on November 6, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Update to RFC 4572 . . . . . . . . . . . . . . . . . . . . . 3 3. Update to RFC 4572 . . . . . . . . . . . . . . . . . . . . . 3
3.1. Update to the sixth paragraph of section 5 . . . . . . . 3 3.1. Update to the sixth paragraph of section 5 . . . . . . . 3
3.2. New paragraphs to the end of section 5 . . . . . . . . . 4 3.2. New paragraphs to the end of section 5 . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 4 7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
RFC 4572 [RFC4572] specifies how to establish Transport Layer RFC 4572 [RFC4572] specifies how to establish Transport Layer
Security (TLS) connections using the Session Description Protocol Security (TLS) connections using the Session Description Protocol
(SDP) [RFC4566]. (SDP) [RFC4566].
RFC 4572 defines the SDP 'fingerprint' attribute, which is used to RFC 4572 defines the SDP 'fingerprint' attribute, which is used to
carry a secure hash value associated with a certificate. However, carry a secure hash value associated with a certificate. However,
RFC 4572 is currently unclear on whether multiple 'fingerprint' can RFC 4572 is currently unclear on whether multiple 'fingerprint' can
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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 [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Update to RFC 4572 3. Update to RFC 4572
This section updates section 5 of RFC 4572. This section updates section 5 of RFC 4572.
3.1. Update to the sixth paragraph of section 5 3.1. Update to the sixth paragraph of section 5
OLD TEXT: OLD TEXT:
A certificate fingerprint MUST be computed using the same one-way A certificate fingerprint MUST be computed using the same one-way
hash function as is used in the certificate's signature algorithm. hash function as is used in the certificate's signature algorithm.
(This ensures that the security properties required for the (This ensures that the security properties required for the
certificate also apply for the fingerprint. It also guarantees that certificate also apply for the fingerprint. It also guarantees that
the fingerprint will be usable by the other endpoint, so long as the the fingerprint will be usable by the other endpoint, so long as the
certificate itself is.) Following RFC 3279 [7] as updated by RFC certificate itself is.) Following RFC 3279 [7] as updated by RFC
4055 [9], therefore, the defined hash functions are 'SHA-1' [11] 4055 [9], therefore, the defined hash functions are 'SHA-1' [11]
[19], 'SHA-224' [11], 'SHA-256' [11], 'SHA-384' [11], 'SHA-512' [11], [19], 'SHA-224' [11], 'SHA-256' [11], 'SHA-384' [11], 'SHA-512' [11]
'MD5' [12], and 'MD2' [13], with 'SHA-1' preferred. A new IANA , 'MD5' [12], and 'MD2' [13], with 'SHA-1' preferred. A new IANA
registry of Hash Function Textual Names, specified in Section 8, registry of Hash Function Textual Names, specified in Section 8,
allows for addition of future tokens, but they may only be added if allows for addition of future tokens, but they may only be added if
they are included in RFCs that update or obsolete RFC 3279 [7]. they are included in RFCs that update or obsolete RFC 3279 [7].
Self-signed certificates (for which legacy certificates are not a Self-signed certificates (for which legacy certificates are not a
consideration) MUST use one of the FIPS 180 algorithms (SHA-1, consideration) MUST use one of the FIPS 180 algorithms (SHA-1,
SHA-224, SHA-256, SHA-384, or SHA-512) as their signature algorithm, SHA-224, SHA-256, SHA-384, or SHA-512) as their signature algorithm,
and thus also MUST use it to calculate certificate fingerprints. and thus also MUST use it to calculate certificate fingerprints.
NEW TEXT: NEW TEXT:
Following RFC 3279 [7] as updated by RFC 4055 [9], therefore, the Following RFC 3279 [7] as updated by RFC 4055 [9], therefore, the
defined hash functions are 'SHA-1' [11] [19], 'SHA-224' [11], defined hash functions are 'SHA-1' [11] [19], 'SHA-224' [11],
'SHA-256' [11], 'SHA-384' [11], 'SHA-512' [11], 'MD5' [12], and 'SHA-256' [11], 'SHA-384' [11], 'SHA-512' [11], 'MD5' [12], and
'MD2' [13], with 'SHA-256' preferred. A new IANA registry of Hash 'MD2' [13], with 'SHA-256' preferred. A new IANA registry of Hash
Function Textual Names, specified in Section 8, allows for addition Function Textual Names, specified in Section 8, allows for addition
of future tokens, but they may only be added if they are included of future tokens, but they may only be added if they are included
in RFCs that update or obsolete RFC 3279 [7]. in RFCs that update or obsolete RFC 3279 [7].
3.2. New paragraphs to the end of section 5 3.2. New paragraphs to the end of section 5
NEW TEXT: NEW TEXT:
Multiple SDP fingerprint attributes can be associated with an m- Multiple SDP fingerprint attributes can be associated with an m-
line. This can occur if multiple fingerprints have been calculated line. This can occur if multiple fingerprints have been calculated
for a certificate, using different hash algorithms. It can also for a certificate, using different hash algorithms. It can also
occur if multiple certificates might be used (e.g. separate occur if fingerprints associated with multiple certificates have
certificates for RTP and RTCP). In such cases, the same number of been calculated, e.g. for cases where multiple certificates will be
fingerprints MUST be calculated for each certificate, and for each used (e.g. separate certificates for RTP and RTCP), or where it is
certificate the same set of hash algorithms MUST be used. not known which certificate will be used when the fingerprints are
exchanged. In such cases, one or more fingerprints MUST be
calculated for each possible certificate. A different number of
fingerprints can be calculated for each certificate, and different
hash algorithms can be used.
An endpoint MUST be able to match at least one of the received An endpoint MUST be able to match at least one of the received
fingerprints with the cerficiate(s) to be used. If there is no fingerprints, calculated using a hash algorithm that the endpoint
match, the endpoint MUST NOT establish the TLS connection. considers secure enough, with the certificate(s) that will
eventually be used. If there is no match, the endpoint MUST NOT
establish the TLS connection.
NOTE: The SDP fingerprint attribute does not contain a reference to NOTE: The SDP fingerprint attribute does not contain a reference to
a specific certificate. Endpoints need to compare all fingerprints a specific certificate. Endpoints need to compare the fingerprint
with the cerficiate hash when looking for a match. witha certificate hash in order to look for a match.
4. Security Considerations 4. Security Considerations
This document improves security. This document improves security. It updates the preferred hash
function cipher suite from SHA-1 to SHA-256. By clarifying the usage
and handling of multiple fingerprints, the document also enables hash
agility, and incremental deployment of newer, and more secure, cipher
suites.
5. IANA Considerations 5. IANA Considerations
This document makes no requests from IANA. This document makes no requests from IANA.
6. Acknowledgements 6. Acknowledgements
Martin Thompson, Paul Kyzivat and Jonathan Lennox provided valuable Martin Thompson, Paul Kyzivat, Jonathan Lennox and Roman Shpount
comments and input on this document. provided valuable comments and input on this document.
7. Change Log 7. Change Log
[RFC EDITOR NOTE: Please remove this section when publishing] [RFC EDITOR NOTE: Please remove this section when publishing]
Changes from draft-ietf-mmusic-4572-update-00
o Changes in handling of multiple fingerprints.
o - Number of fingerprints calculated for each certificate does not
have to match.
o - Clarified that receiver shall check check fingerprints using
hash algorithms it considers safe.
o - Additional text added to security considerations section.
Changes from draft-holmberg-mmusic-4572-update-01 Changes from draft-holmberg-mmusic-4572-update-01
o Adopted WG document (draft-ietf-mmusic-4572-update-00) submitted. o Adopted WG document (draft-ietf-mmusic-4572-update-00) submitted.
o IANA considerations section added. o IANA considerations section added.
8. Normative References 8. 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, Requirement Levels", BCP 14, RFC 2119,
 End of changes. 16 change blocks. 
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