Hi,

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.

The summary of the review is Ready.

I'd like to suggest that the authors consider recommending that a mechanism to protect the header be utilized if there is a concern that a malicious attacker may surreptitiously attempt to change the value of the Expires header field. The authors will likely know what mechanisms may be used better than me.

Best regards,
Chris