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. Description: This document updates RFC4121< http://tools.ietf.org/html/rfc4121 > to allow channel bindings using algorithms negotiated based on Kerberos crypto framework as defined in RFC3961< http://tools.ietf.org/html/rfc3961 >. In addition, because this update makes use of the last extensible field in the Kerberos client-server exchange message, extensions are defined to allow future protocol extensions. I think the document is ready. The only suggestion would be to consider expanding out the security consideration section to list any risks with using or not using channel bindings. Right now, it states it is up to the application's policy, which is fine, but may leave developers with questions. Telechat is on 12-30-2011 Thank you, Kathleen