I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comments.

This document describes a modification to the SRTP protocol, wherein header fields which have previously only been protected with authentication may now also be protected with (authenticated) encryption. The document is detailed and well-written, and the document text, together with the security considerations section, seems to address all relevant concerns.

I want to qualify my comments: I had relatively short notice for this document review, I have no prior experience with SRTP, and I have been very busy with post-Holiday catch-up, so I have to apologize for not giving this document more attention. On the other hand, there are a number of highly respected reviewers mentioned in the acknowledgements section, so I think odds are good that this document raises no serious concerns.

--Scott