GIT-CERCS-07-10
David Bauer, Douglas Blough, David Cash,
Minimum Information Disclosure with Efficiently Verifiable Credentials
Public-key based certificates provide a standard way to prove
one's identity, as certified by some certificate authority (CA).
However, standard certificates provide a binary identification:
either the whole identity of the subject is known, or nothing is
known. We propose using a Merkle hash tree structure, whereby
it is possible for a single certificate to certify many separate claims
or attributes, each of which may be proved independently, without
revealing the others. Additionally, we demonstrate how trees from
multiple sources can be combined together by modifying the tree
structure slightly. This allows claims by different authorities, such
as an employer or professional organization, to be combined
under a single certificate, without the CA needing to know (let
alone verify) all of the claims. In addition to describing the hash
tree structure and protocols for constructing and verifying our
proposed credential, we formally prove that it provides
unforgeability and privacy and we present initial performance
results demonstrating its efficiency.