In message <[EMAIL PROTECTED]>, Adam Back writes: >Doesn't a standard digital signature plus hashcash / client puzzles >achieve this effect? > >The hashcash could be used to make the client to consume more cpu than >the server. The hashcash collision wouldn't particularly have to be >related to the signature, as the collision would just act as a >proof-of-work entitling the client to have the server verify the >accompanying signature. >
That involves extra round trips, and as such isn't suitable for all uses. --Steve Bellovin, http://www.research.att.com/~smb (me) http://www.wilyhacker.com ("Firewalls" book) --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]