Right. Consistency with Mac is probably King here, but there is no need to indicate truncation in the algorithm identifier, as the byte string itself already indicates truncation---if there is a consistent way to do this for an algorithm id.
Sent from mobile > On 28. Feb 2018, at 07:28, Jim Schaad <[email protected]> wrote: > > For the draft that I originally wrote, the truncated length is part of the > algorithm identifier just like it is with the MAC algorithms. I will get it > republished and make sure that it is ready to go. I can probably get an AD > to pick it up in London. > > Jim > > > From: Carsten Bormann [mailto:[email protected]] > Sent: Tuesday, February 27, 2018 10:10 PM > To: Jim Schaad <[email protected]> > Cc: [email protected] > Subject: Re: [COSE] Digests (hashes) in COSE? > > In the specific case, there would be multiple hashes all under the same > algorithm id, so the data structure would be pretty trivial... Maybe we just > need the iana considerations for registering hash functions plus some text > how to truncate. > > Sent from mobile > > On 28. Feb 2018, at 01:48, Jim Schaad <[email protected]> wrote: > > I need to re-publish my document with hash algorithms, however I am not sure > what needs to be placed in this structure in some ways. > > Is there something beyond > > MAC = [ > Digest : bstr, > Algorithm: alg_id > ] > > If you start trying to carry the content you end up with problems because it > is just as often pointed to. Not sure that putting the pointer in the digest > computation would make sense as this value often chances as well. > > Are you thinking of something specific that should be part of this? > > I am not sure just how strong the demand is for parametrized hash algorithms > is. I have used a couple in my lifetime, but always as cases to see what > would happen and have never used one in the wild. > > Jim > > > > -----Original Message----- > From: COSE [mailto:[email protected]] On Behalf Of Carsten Bormann > Sent: Monday, February 26, 2018 9:01 AM > To: [email protected] > Subject: [COSE] Digests (hashes) in COSE? > > I think that has come up before, but today in the SUIT WG Interim we briefly > discussed a structure where it would be useful to contain multiple unkeyed > digests (hashes) in one signed claim (*). In COSE, we have a registry for > keyed MAC schemes, but not for hashes. We also don’t have a COSE_Digest > structure (which would be quite simple, I believe) either (**). > > To avoid everyone defining their own way of describing hashes, should we > be setting this up for COSE? > We would have to be fast to be relevant for SUIT. > > Grüße, Carsten > > (*) https://tools.ietf.org/html/draft-moran-suit-manifest-01#section-4 > (**) maybe a bit like CMS digestedData, but simpler of course > > _______________________________________________ > COSE mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/cose > >
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