Suppose I have two users who are issued two different UProve IDs. The Issuer has guaranteed that one UProve token bearer will never have more than one UProve token ID.
- How can I use UProve to guarantee that two users are "different" without disclosing their actual private ID?
Here is a scenario: An online voting system wants to use UProve to anonymously collect votes. They decide to trust an
Issuer who has full knowledge of the end user, but the
relying pary has to accept the fact that they will know nothing about the end user at all.
The polling station (
relying party) only needs to know that the same UProve ID wasn't used to cast a second vote. The only UProve scenario I know of that would work here is proving the user's SSN (or similar fixed ID).
In this case I don't want to disclose anything.
Is this possible?