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 just updates the HTTP digest algorithm values, and as such doesn't really have security considerations. First a question...this isn't a cryptographic checksum, and it might be nice if the document said what its purpose is. I assume it's for caching, so that you can quickly check if a page has changed? Now not to pick on this spec, but perhaps something IETF might consider, two issues: Terminology issue: even though people routinely use the terminology "SHA-256", perhaps it's time to also include the version of SHA, as in SHA-2-256, since other versions of SHA might have overlapping sizes with SHA-1 and SHA-256. And having a registry for each algorithm for each protocol seems unwieldly---each time a new algorithm happens, does it mean a bunch of specs have to come out with an update document like this one? Could it instead be a single registry that all specs point to? Radia