...

...

...

...

Steve Schear <azur@netcom.com> writes:

[much cut]

...

I've been charged with developing an Internet service which needs to

assure

...

its clients of anonymity. However, we fear some clients may abuse the service and we wish to prevent the abusers from re-enrollment if terminated for misbehavior. (In your example, it would be the person(s) trying to discover the service host via flood).

My thought was to base enrollment on some sort of 'blinding' of their certified signature (e.g., from Verisign) which produces a unique result for each signature but prevents the service from reconstructing the signature itself (and thereby reveal the client's identity). I'm calling this negative authentication.

(Sorry about quoting so much, but I liked Steve Schear's succinct problem statement.)

I don't see how authorization certificates solve this problem. How would you determine if someone was qualified to receive an authorization certificate? And what would you do to make them stop using the service if they abuse it, and to stop them from getting new authorization certificates?

Thanks, Hal

It seems that one crux of the problem revolves around the CA and its method of certificate issuance. A CA which uses biometric data to reduce/eliminate the chance that an applicant could get several, unrelated, certificates issued would provide a basis for negative authentication (similar to a negative credit file). A one-way function performed, by the client, on their certificate from this CA would yield a token which unambiguously binds it to a valid certificate of the CA (and therefore uniquely identifies them) w/o revealing the certificate itself. -- Steve