Request for Publication
November 5, 2021
Document: Completely Encrypting RTP Header Extensions and Contributing Sources
Link: https://datatracker.ietf.org/doc/html/draft-ietf-avtcore-cryptex
Intended Status: Proposed Standard
Document Shepard: Bernard Aboba
WG: AVTCORE
(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the proper
type of RFC? Is this type of RFC indicated in the title page header?
Publication as a Proposed Standard is requested.
(2) The IESG approval announcement includes a Document Announcement Write-Up.
Please provide such a Document Announcement Write-Up. Recent examples can be
found in the "Action" announcements for approved documents. The approval
announcement contains the following sections:
Technical Summary:
While the Secure Real-time Transport Protocol (SRTP) provides
confidentiality for the contents of a media packet, a significant
amount of metadata is left unprotected, including RTP header
extensions and contributing sources (CSRCs). While there have been
previous attempts to protect this data, they have had limited
deployment, due to complexity as well as technical limitations.
This document defines Cryptex as a new mechanism that completely
encrypts header extensions and CSRCs and uses simpler signaling with
the goal of facilitating deployment.
Working Group Summary:
RTP header extensions contain information that can be considered
sensitive from a privacy perspective, such as audio levels
and video content types.
RFC 6904, the initial attempt at protecting RTP header extensions,
has not been (correctly) implemented in a widespread way. RFC 6904
requires implementations to offer extensions in both encrypted/unencrypted
forms, with negotiation of encryption for each extension and resulting
SDP bloat (since every extmap requires 2 lines). The complexity has
hindered adoption of RFC 6904, with bugs in implementations such as
libsrtp going undetected for 5+ years.
Since RFC 6904 only encrypts the body of RTP header extensions, but
not the ID or length fields, even when successfully negotiated it
reveals significant information about the application. In addition
RFC 6904 does not protect RTP header fields such as contributing
sources (CSRCs).
As a result, WG consensus was that a new approach was needed.
Cryptex simplifies the deployment model by encrypting RTP
header extensions as a block as well as increasing the scope of
protection to include CSRCs.
Recent discussion with the AVTCORE WG have centered on
clarifying and reducing the complexity of Session
Description Protocol (SDP) negotiation.
Document Quality:
There are two known implementations: one in Jitsi, as well as a PR for
libsrtp which has not yet been merged. The implementations have been
checked against test vectors. A proposal for adding support within the
WebRTC API is under development.
Personnel:
Who is the Document Shepherd? Who is the Responsible Area Director?
Bernard Aboba is the Document Shepard. Responsible AD is Murray Kutcheraway.
(3) Briefly describe the review of this document that was performed by the
Document Shepherd. If this version of the document is not ready for
publication, please explain why the document is being forwarded to the IESG.
The Document Shepard has reviewed the document as part of WGLC, and made
comments that were subsequently addressed by the authors.
(4) Does the document Shepherd have any concerns about the depth or breadth of
the reviews that have been performed?
Recent WG discussion has centered on the SDP section, so this may deserve
further scrutiny.
(5) Do portions of the document need review from a particular or from broader
perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or
internationalization? If so, describe the review that took place.
Additional review by the SDP Directorate may be helpful.
(6) Describe any specific concerns or issues that the Document Shepherd has
with this document that the Responsible Area Director and/or the IESG should be
aware of? For example, perhaps he or she is uncomfortable with certain parts of
the document, or has concerns whether there really is a need for it. In any
event, if the WG has discussed those issues and has indicated that it still
wishes to advance the document, detail those concerns here.
No concerns.
(7) Has each author confirmed that any and all appropriate IPR disclosures
required for full conformance with the provisions of BCP 78 and BCP 79 have
already been filed. If not, explain why?
Yes.
Cullen Jennings:
https://mailarchive.ietf.org/arch/msg/avt/zgLFBTqUca4b8ARwFJnXJOF-1Cw/ Sergio
Garcia Murillo:
https://mailarchive.ietf.org/arch/msg/avt/E9unITw6snUlQwtvHZYReGKk5Gg/ Justin
Uberti: https://mailarchive.ietf.org/arch/msg/avt/IO_3J21OrD2wCVXFxv5zrXwg8ik/
(8) Has an IPR disclosure been filed that references this document? If so,
summarize any WG discussion and conclusion regarding the IPR disclosures.
No disclosures.
(9) How solid is the WG consensus behind this document? Does it represent the
strong concurrence of a few individuals, with others being silent, or does the
WG as a whole understand and agree with it?
The WG has multiple participants who have been involved in the development of
cryptex, as well as implementation of RFC 6904.
The consensus in favor of the document appears solid.
(10) Has anyone threatened an appeal or otherwise indicated extreme discontent?
If so, please summarise the areas of conflict in separate email messages to the
Responsible Area Director. (It should be in a separate email because this
questionnaire is publicly available.)
There have been no heated discussions or indication of extreme (or even mild)
discontent. No threats of an appeal.
(11) Identify any ID nits the Document Shepherd has found in this document.
(See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist).
Boilerplate checks are not enough; this check needs to be thorough.
Checking boilerplate required by RFC 5378 and the IETF Trust (see
https://trustee.ietf.org/license-info):
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No issues found here.
Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt:
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No issues found here.
Checking nits according to https://www.ietf.org/id-info/checklist :
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No issues found here.
Miscellaneous warnings:
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-- The document date (25 October 2021) is 10 days in the past. Is this
intentional?
Checking references for intended status: Proposed Standard
----------------------------------------------------------------------------
(See RFCs 3967 and 4897 for information about using normative references
to lower-maturity documents in RFCs)
** Obsolete normative reference: RFC 4566 (Obsoleted by RFC 8866)
Summary: 1 error (**), 0 flaws (~~), 0 warnings (==), 1 comment (--).
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(12) Describe how the document meets any required formal review criteria, such
as the MIB Doctor, YANG Doctor, media type, and URI type reviews.
The document does not appear to require any formal reviews (e.g. no MIB or YANG
modules, or media type/URI type definitions).
(13) Have all references within this document been identified as either
normative or informative?
References are separated into normative and informative categories.
(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative references
exist, what is the plan for their completion?
No.
(15) Are there downward normative references references (see RFC 3967)? If so,
list these downward references to support the Area Director in the Last Call
procedure.
No.
(16) Will publication of this document change the status of any existing RFCs?
Are those RFCs listed on the title page header, listed in the abstract, and
discussed in the introduction? If the RFCs are not listed in the Abstract and
Introduction, explain why, and point to the part of the document where the
relationship of this document to the other RFCs is discussed. If this
information is not in the document, explain why the WG considers it unnecessary.
No changes to the status of existing RFCs. This document does not obsolete RFC
6904.
(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes are
associated with the appropriate reservations in IANA registries. Confirm that
any referenced IANA registries have been clearly identified. Confirm that newly
created IANA registries include a detailed specification of the initial
contents for the registry, that allocations procedures for future registrations
are defined, and a reasonable name for the new registry has been suggested (see
RFC 8126).
I have reviewed the IANA Considerations, Section 9.
(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful in
selecting the IANA Experts for these new registries.
No IANA registries are created.
(19) Describe reviews and automated checks performed by the Document Shepherd
to validate sections of the document written in a formal language, such as XML
code, BNF rules, MIB definitions, YANG modules, etc.
No formal languages.
(20) If the document contains a YANG module, has the module been checked with
any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) for syntax and
formatting validation? If there are any resulting errors or warnings, what is
the justification for not fixing them at this time? Does the YANG module comply
with the Network Management Datastore Architecture (NMDA) as specified in
RFC8342?
No YANG modules.