Subject: [bfcpbis] comment on draft-sandbakken-dispatch-bfcp-udp-03 text on DTLS connection establishment

From: "Charles Eckel (eckelcu)" <[email-masked]>
Date: Thu, 10 Nov 2011 12:04:52 -0800

There is an inconsistency in draft-sandbakken-dispatch-bfcp-udp-03 in
terms of its recommendations regarding DTLS connection establishment.
Section 4.10. Lower-Layer Security (7) currently reads:

      Which party, the client or the floor control server, acts as the
      TLS/DTLS server depends on how the underlying TCP/DTLS connection
      is established.  For example, when the TCP/DTLS connection is
      established using an SDP offer/answer exchange [RFC4583], the
      answerer (which may be the client or the floor control server)
      always acts as the TLS/DTLS server.

This extends the existing text in RFC 4582 to cover DTLS as well.
However, section 5.3. Security Considerations (10) of
draft-sandbakken-dispatch-bfcp-udp-03 reads:

   Append to the first paragraph, "Furthermore, when using DTLS over
   UDP, considerations for its use with RTP and RTCP are presented in
   [RFC5763].  The requirements for the offer/answer exchange, as listed
   in Section 5 of that document, MUST be followed."

This conflicts with what was stated in section 4.10, as the
recommendations for DTLS connection establishment in RFC 5763 are not
the same as those provided in RFC 4583 for TLS connection establishment.

The proposed rewording of the text in section 4.10 of
draft-sandbakken-dispatch-bfcp-udp-03 is as follows:

      Which party, the client or the floor control server, acts as the
      TLS/DTLS server depends on how the underlying TLS/DTLS connection
      is established.  For a TCP/TLS connection established using an SDP
      offer/answer exchange [RFC4583], the answerer (which may be the
client
      or the floor control server) always acts as the TLS server.  For a
      UDP/DTLS connection established using the same exchange, either
party
      can be the DTLS server depending on the setup attributes
exchanged,
      as defined in [RFC5763].

Cheers,
Charles