Abstract: Computer-implemented methods for privacy attribute based credentials include issuing a privacy-preserving attribute-based credential, which is signed with a private key and has a unique credential handle; updating an accumulator in a tamperproof log to incorporate the credential handle; and facilitating providing access to a service in response to a zero-knowledge proof that the accumulator contains the credential handle. The methods also include generating revocation conditions and initial revocation information; submitting the initial revocation information and the revocation conditions to the tamperproof log; revoking a credential by adding a credential handle of the credential to the initial revocation information; and submitting the updated revocation information to the tamperproof log. Further, the methods include writing to the tamperproof log an audit token that contains an encrypted credential handle, which is encrypted by an auditor's public key that is published on the tamperproof log.

Abstract: Computer-implemented methods for privacy attribute based credentials include issuing a privacy-preserving attribute-based credential, which is signed with a private key and has a unique credential handle; updating an accumulator in a tamperproof log to incorporate the credential handle; and facilitating providing access to a service in response to a zero-knowledge proof that the accumulator contains the credential handle. The methods also include generating revocation conditions and initial revocation information; submitting the initial revocation information and the revocation conditions to the tamperproof log; revoking a credential by adding a credential handle of the credential to the initial revocation information; and submitting the updated revocation information to the tamperproof log. Further, the methods include writing to the tamperproof log an audit token that contains an encrypted credential handle, which is encrypted by an auditor's public key that is published on the tamperproof log.