Are you subscribed to coderpunks - this sounds very much like the SolidOak project on we're working on; this uses embedded singatures to authenticate bodies which vouch for the integrity of a class and it's referenced sub-classes. The current spec doesn't have dates for expiry in there, and doesn't really have versions for referenced classes (needs exact hashes), but does support signatures being added by multiple authorites at different times. It uses the Dns from the signatures as extra keys into the ACL. I have to demo the currently speced system next week; after that I'll be trying to merge the spec with another simiar scheme to give a common standard for signed java classes; I'll try and post the spec as it currently stands tommorow when I'm at my dragon and can correct a few bits that got changed during implementation. Simon --- They say in online country So which side are you on boys There is no middle way Which side are you on You'll either be a Usenet man Which side are you on boys Or a thug for the CDA Which side are you on? National Union of Computer Operatives; Hackers, local 37 APL-CPIO