Subject: [AVT] comments on draft-mcgrew-srtp-ekt-04

From: Roni Even <[email-masked]>
Date: Wed, 27 May 2009 20:18:00 +0300

Hi,

I read the draft and think it would be very useful.

I have some comments

1.       RFC 5117 describes the different multi endpoints  topologies. I
suggest that this draft  should reference it and maybe update RFC 5117
mostly with regards to  section 5 (security consideration) of the
topologies. Section 5 concludes that mixer or translators need to be part of
the security context. Is there a case that EKT make it possible to reduce
this requirement. The text in the important note in section 3.5.1 discourage
using EKT for RTP transport translators.

2.       Section 7 suggests using RTP transport if RTCP is not available.
RTCP is not optional part of the protocol so I think this section should not
be part of the draft.

3.       Section 3.7  "Finally, subsequent offer/answer exchanges MUST NOT
remap a given SPI value to a different EKT parameter set until 2^32 other
mappings have been used within the SRTP session."   SPI is 16 bit according
to figure 1.

Thanks

Roni Even