On Thu, Oct 30, 2003 at 01:15:23PM -0600, Tom Kaitchuck wrote: > On Thursday 30 October 2003 12:49 pm, Toad wrote: > > I think Tom's idea was to make the creator of a URL do the expensive > > calculation, perhaps while waiting for the insert to work. Hence: > > CHK@<hashcash/routing key>,<hash of encrypted content>,<decrypt key> > > Where <routing key> is derived from <hash of encrypted content> by some > > operation, say a large number of operations of a secure hash. > > > > This could be a nice idea, the only problem is extending it to SSKs: > > SSK@<pubkey hash>,<encryption entropy>,<hashcash>/<filename> > > Where <routing key> is derived from the others, and applies to the > > manifest file. The problem here is that the routing key cannot be > > derived from the filename, as we want the filename to vary within the > > SSK 'directory' - even if we use mapfiles, DBRs require > > SSK@<FIXED>/<changing string> > > > > One possibility would be for the hashcash to be derived once only for > > the SSK - but then we lose any security this gains us against flooders. > > I don't think that hashcash in the URL is compatible with subspace keys, > > sorry Tom. > > Why not? For CHK: > [EMAIL PROTECTED],<hash>,<decrypt key> > where <Decrypt key> decrypts > and H(hash) routes > and H(hash+XXX) verifies. > All you have to send is hash and XXX. > For SSK: > [EMAIL PROTECTED],<key>,<name> > where <key> decrypts > and H(H(key+name)) routes > and H(H(key+name)+XXX) verifies. > All you have to send is H(key+name) and XXX. > > Why wouldn't this work?
Because if XXX is common, the attacker only needs to compute it once. > > > A further problem is that you need to be able to increase the required > > amount of hashcash over time, as machines become able to do more > > hashcash - this is NOT good for URLs! > > Well at least it would not affect routing. If at first we allocate 3 > characters to XXX then that means we can make them do 2^18 hashes. If that is > not enough goto 10 that's 2^60 hashes. Even if the average computer doubles > in speed every 18 months we should only need to add one character to the URI > every 9 years. The problem is we need to keep the time to compute it reasonable within current technology, while not letting it get too low as to not be useful. That means we need to update it regularly. Hmm, maybe we don't have to route by XXX though, yeah. We could route by the existing key and just verify XXX, which is derived from the routing key amongst other things? Interesting. -- Matthew J Toseland - [EMAIL PROTECTED] Freenet Project Official Codemonkey - http://freenetproject.org/ ICTHUS - Nothing is impossible. Our Boss says so.
signature.asc
Description: Digital signature
_______________________________________________ Devl mailing list [EMAIL PROTECTED] http://dodo.freenetproject.org/cgi-bin/mailman/listinfo/devl
