Digital credentials with privacy‐preserving delegation

Abstract

This paper extends digital credentials, a cryptographic scheme that provides provably secure, private, attribute certificates. We give a method for the delegation of these credentials, which allows the delegator to reveal a subset of his/her credentials to a delegatee, who in turn can control revelation of this subset to a verifier. Our method also supports blinded showing of credentials to a specified verifier in order to hide the credentials from the delegatee, when desired. Privacy is preserved in all cases under a strong attack model that includes collusion between an attacker (Malice) and the Certification Authority that issued the credentials.