Patent ID: 8689000

Claim:
A method of determining access to computational resources by means of a group signature scheme with revocation evidence, the method comprising: a certificate issuer holding a group secret key and providing a group public key; a group member obtaining a membership secret and the certificate issuer providing a membership certificate for the group member in respect of the membership secret; the group member using a computing apparatus to demonstrate possession of a valid membership secret and a valid membership certificate to a verifier without revealing the membership secret or the membership certificate to the verifier, wherein demonstrating possession includes generating a signature and revocation evidence from the membership secret and a revocation parameter and providing the signature and the revocation evidence to the verifier; and the verifier determining from the signature and from the revocation evidence that the group member possesses a valid membership secret and a valid membership certificate, wherein no verifier, not even the certificate issuer, is able to identify the group member from the signature and the revocation evidence.