Gen-ART review ofdraft-ietf-rtcweb-alpn-03

[Russ Housley <[e-mail]>]

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Document: draft-ietf-rtcweb-alpn-03
Reviewer: Russ Housley
Review Date: 2016-04-18
IETF LC End Date: 2016-04-21
IESG Telechat date: unknown

Summary:  Almost Ready

Major Concerns:  None


Minor Concerns:

In several places, the document says: "These confidentiality protections
do not apply to data that is sent using data channels."  It took me a
moment to figure out what was being said.  I think it would really help
the reader to say at the beginning something like: "The confidentiality
protections ensure that media is protected from other applications, but
the confidentiality protections do not extend to traffic on the data
channels."

Section 3 includes this paragraph:

   Generally speaking, ensuring confidentiality depends on
   authenticating the communications peer.  This mechanism explicitly
   does not define a specific authentication method; a WebRTC endpoint
   that accepts a session with this ALPN identifier MUST respect
   confidentiality no matter what identity is attributed to a peer.

I understand why authentication and confidentiality are often used
together.  However, it is very unclear to me why there ought to be a
linkage between c-webrtc and authentication since this service really
is only a promise to not share media with other applications.

A similar discussion in the security considerations talks about
assurance that the "media was delivered to the user that was
authenticated."  Again, if there is no authentication, I do not see
how the assurance associated with this mechanism changes.


Nits:

After reading the whole document, I went back and read the Abstract
again.  I do not think it captures the real intent of the document.
I have tried to provide an alternative, but it probably needs further
work:

   This document specifies two Application Layer Protocol Negotiation
   (ALPN) labels for use with Datagram Transport Layer Security (DTLS)
   and Web Real-Time Communications (WebRTC).  With the first label, a
   DTLS session is used to establish keys for Secure Real-time Transport
   Protocol (SRTP), known as DTLS-SRTP.  The second label also uses
   DTLS-SRTP, but the peers also agree to maintain the confidentiality
   of the media by not sharing it with other applications.