A prover of a data processing system may prove to a verifier of the system that the prover satisfies a condition imposed by the verifier. The prover holds in memory at least one cryptographic credential in which are encoded a biometric template characteristic of the prover and a set of prover attributes such that each of the template and attributes are bound to a common secret value of the prover. A biometric measurement is made of the prover, which then communicates with the verifier to make a cryptographic proof demonstrating: possession of the cryptographic credential; that the biometric measurement matches the biometric template encoded in the cryptographic credential; and that the set of prover attributes encoded in the cryptographic credential satisfies the condition imposed by the verifier. The cryptographic proof is made without revealing the template or the at least one credential to the verifier.