Christian Paquin wrote: > Adam Back wrote: >> On Tue, Apr 04, 2006 at 06:15:48AM +0100, Ben Laurie wrote: >>> Brands actually has a neat solution to this where the credential is >>> unlinkable for n shows, but on the (n+1)th show reveals some secret >>> information (n is usually set to 1 but doesn't have to be). >> >> I think they shows are linkable, but if you show more than allowed >> times, all of the attributes are leaked, including the credential >> secret key and potentially some identifying information like your >> credit card number, your address etc. > > In Brands' system, multiple uses of a n-show credential are not linkable > to the issuing (i.e. they are untraceable), but they are indeed linkable > if presented to the same party: the verifier will recognize the > credential when re-used. This is useful for limited pseudonymous access > to accounts or resources. If you want showing unlinkability, better get > n one-show credentials (simpler and more efficient).
That's only true if the credential contains any unblinded unique data, surely? Cheers, Ben. -- http://www.links.org/ --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]