On Fri, 15 Aug 2008 20:35:52 -0600 Peter Saint-Andre <[EMAIL PROTECTED]> wrote:
> Peter Saint-Andre wrote: > > Zenon Kuder jr. wrote: > >> Actually the idea (I talked with Pavel by IM a bit) is that client > >> a) either uses hash, checks the incoming data and caches per hash > >> or b) doesn't know the hash or hash wasn't used or doesn't support > >> hashes and then caches per JID and per the unique string. > >> > >> I hope I got it right and clear :-). > > > > Yes, that seems good. > > We might even want to harmonize BoB with User Avatar (XEP-0084). > There we have: > > <metadata xmlns='urn:xmpp:avatar:metadata'> > <info bytes='size-of-image-data-in-bytes' > height='image-height-in-pixels' > id='SHA-1-hash-of-image-data' > type='content-type-of-image-data' > url='HTTP-URL-for-image-data' > width='image-width-in-pixels'/> > </metadata> > > So hashes of user avatar images could be compared against BoB data, > too (without changing XEP-0084, unless we want to add a 'cid' > attribute there). Not sure if this is useful. But what we need to do is both specify the metadata format... and to specify how we compute the hash. I propose (as a possibility): For sha-1: h = sha-1 Generally: hashed_value = h( h(content-type) + h(content) ) where + stands for concatenation. If we include the metadata, it would be good to add it to the hash too (just as we concatenated hashes of content-type and content) in some way. This would ensure we get the same type, data and metadata for a particular hash :) which is nice ;). Pavel > /psa -- Web: http://www.pavlix.net/ Jabber & Mail: pavlix(at)pavlix.net OpenID: pavlix.net
