eSketch: a Privacy-Preserving Fuzzy Commitment Scheme for Authentication using Encrypted Biometrics

The fuzzy commitment approach has gained popularity as a way to protect biometric data used for identity verification of authentication. As it has been show recently, though, the use of fuzzy commitment is unavoidably linked to some leakage of information regarding the biometric template. An additional problem typical of authentication systems is that the user may want to protect his privacy, that is it would be desirable that the server only verifies whether the biometric template provided by the user is contained within the list of registered users without that the particular identity of the user accessing the system is revealed. The e-sketch protocol proposed in this paper, solves the above two problems by resorting to tools from Multi Party Computation relying on the additively homomorphic property of the underlying cryptosystem (e.e. the Pailler's cryptosystem). The security and the complexity of the proposed protocol are discussed.