Re: [AVTCORE] I-D Action: draft-ietf-avtext-framemarking-15.txt

["Mo Zanaty (mzanaty)" <[e-mail]>]

This revision addresses the open DISCUSS related to privacy considerations.

The new text of this section is below.

https://datatracker.ietf.org/doc/html/draft-ietf-avtext-framemarking-15#name-security-and-privacy-consid

4. Security and Privacy Considerations

In the Secure Real-Time Transport Protocol (SRTP) [RFC3711<https://www.rfc-editor.org/info/rfc3711>], RTP header extensions are authenticated and optionally encrypted [RFC9335<https://www.rfc-editor.org/info/rfc9335>]. When unencrypted header extensions are used, some metadata is exposed and visible to middle boxes on the network path, while encrypted media data and metadata in encrypted header extensions are not exposed.

The primary utility of this specification is for RTP switches to make proper media forwarding decisions. RTP switches are the SRTP peers of endpoints, so they can access encrypted header extensions, but not end-to-end encrypted private media payloads. Other middle boxes on the network path can only access unencrypted header extensions, since they are not SRTP peers.

RTP endpoints which negotiate this extension should consider whether this video frame marking metadata needs to be exposed to the SRTP peer only, in which case the header extension can be encrypted; or whether other middle boxes on the network path also need this metadata, for example, to optimize packet drop decisions that minimize media quality impacts, in which case the header extension can be unencrypted, if the endpoint accepts the potential privacy leakage of this metadata. For example, it would be possible to determine keyframes and their frequency in unencrypted header extensions. This information can often be obtained via statistical analysis of encrypted data. For example, keyframes are usually much larger than other frames, so frame size alone can leak this in the absence of any unencrypted metadata. However, unencrypted metadata provides a reliable signal rather than a statistical probability; so endpoints should take that into consideration to balance the privacy leakage risk against the potential benefit of optimized media delivery when deciding whether to negotiate and encrypt this header extension.

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From: avt <[e-mail]> on behalf of [e-mail] <[e-mail]>
Sent: Wednesday, July 26, 2023 12:47:26 PM
To: [e-mail] <[e-mail]>
Cc: [e-mail] <[e-mail]>
Subject: [AVTCORE] I-D Action: draft-ietf-avtext-framemarking-15.txt


A New Internet-Draft is available from the on-line Internet-Drafts
directories. This Internet-Draft is a work item of the Audio/Video Transport
Core Maintenance (AVTCORE) WG of the IETF.

   Title           : Video Frame Marking RTP Header Extension
   Authors         : Mo Zanaty
                     Espen Berger
                     Suhas Nandakumar
   Filename        : draft-ietf-avtext-framemarking-15.txt
   Pages           : 16
   Date            : 2023-07-26

Abstract:
   This document describes a Video Frame Marking RTP header extension
   used to convey information about video frames that is critical for
   error recovery and packet forwarding in RTP middleboxes or network
   nodes.  It is most useful when media is encrypted, and essential when
   the middlebox or node has no access to the media decryption keys.  It
   is also useful for codec-agnostic processing of encrypted or
   unencrypted media, while it also supports extensions for codec-
   specific information.

The IETF datatracker status page for this Internet-Draft is:
https://datatracker.ietf.org/doc/draft-ietf-avtext-framemarking/

There is also an htmlized version available at:
https://datatracker.ietf.org/doc/html/draft-ietf-avtext-framemarking-15

A diff from the previous version is available at:
https://author-tools.ietf.org/iddiff?url2=draft-ietf-avtext-framemarking-15

Internet-Drafts are also available by rsync at rsync.ietf.org::internet-drafts


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