[secdir] [new-work] WG Review: SIP Best-practice Recommendations Against Network Dangers to privacY (sipbrandy)

[The IESG <[e-mail]>]

A new IETF WG has been proposed in the Applications and Real-Time Area.
The IESG has not made any determination yet. The following draft charter
was submitted, and is provided for informational purposes only. Please
send your comments to the IESG mailing list ([e-mail]) by
2016-06-27.

SIP Best-practice Recommendations Against Network Dangers to privacY
(sipbrandy)
-----------------------------------------------------------------------
Current status: Proposed WG

Chairs:
  Gonzalo Camarillo <[e-mail]>

Assigned Area Director:
  Ben Campbell <[e-mail]>

Applications and Real-Time Area Directors:
  Ben Campbell <[e-mail]>
  Alissa Cooper <[e-mail]>
  Alexey Melnikov <[e-mail]>
 
Mailing list:
  TBD

Charter: https://datatracker.ietf.org/doc/charter-ietf-sipbrandy/

SIP with the SDP Offer/Answer model, along with RTP are widely used in
modern communications networks. But while secure RTP (SRTP) is available
to provide integrity and privacy protection to such communication, it is
rarely used end-to-end. This lack is due to several factors, notably the
pervasive use of signaling and media intermediaries in such networks and
the difficulties involved in deployment of strong identity mechanisms
for SIP. These factors are complicated by the fact that there are
several incompatible approaches to SRTP key exchange.

The current situation is unacceptable in the face of pervasive
monitoring, which RFC 7258 describes as "an attack on privacy". In
addition, the STIR working group is, at the time of this writing,
revising RFC 4744 to make strong identity attestations for SIP easier to
deploy. This gives the IETF an opportunity to define best practices to
improve privacy protections for users of SIP based communication, in
ways that improve upon the status-quo.

Objectives:

The SIPBRANDY working group will define best practices for establishing
two-party, SIP-signaled SRTP sessions with end-to-end security
associations, including a single, preferred SRTP key exchange mechanism.
These practices are expected to be deployable across typical SIP
networks, without the sharing of SRTP keying material with
intermediaries or third parties. These practices should protect against
man-in-the-middle attacks. 

While confidentiality is the first priority of the working group, it may 
work on aligning these practices with WebRTC, for example by defining
best practices for ensuring recipients of media flows have indicated the 
desire to receive them, in order to prevent or mitigate the
denial-of-service attack described in RFC 5245, section 18.5.1. 
Likewise, the WG may consider compatibility with aspects of PERC.

The working group will additionally coordinate with the MMUSIC working
group to define opportunistic security [RFC 7435] for SIP-signaled media 
sessions for situations where strong protections are not necessary or not
feasible.

Non-Goals:

The working group is not expected to define practices for multi-party
session topologies, especially those involving media distribution
devices.

The working group is not expected to define new protocols or modify
existing ones; rather it will define practices for using existing
protocols. If the working group discovers gaps that require creation or
modification protocols, it will forward those gaps to the appropriate
working groups.

Inputs and Collaboration:

The WG will consider draft-peterson-dispatch-rtpsec and
draft-johnston-dispatch-osrtp as input to the work. The WG is expected
to collaborate closely with SIPCORE, AVTCORE, STIR, MMUSIC, RTCWEB, 
PERC, and possibly DISPATCH.

Milestones:
  Aug 2016 - Draft Adoption - Best Practices for end-to-end SRTP
  Nov 2016 - Draft Adoption - Best Practices for Opportunistic SRTP
  Mar 2017 - Submit End-to-End SRTP draft to the IESG for consideration
as BGP
  Mar 2017 - Inform MMUSIC or other appropriate WGs of any changes needed
to support Opportunistic SRTP (Not expected to be published as an RFC)
  Nov 2017 - Submit Opportunistic SRTP draft to IESG for consideration as
BGP


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