A Blockchain Consensus Protocol Based on Fuzzy Signatures.

We propose a protocol to jointly achieve authentication and consensus on a blockchain network, in which endpoints are required to digitally sign some random message using fuzzy keys according to a classic fuzzy signature paradigm typical, for example, of biometric authentication. We consider classic RSA digital signatures, showing that fuzziness in the secret key translates into some noise affecting the derived signatures. The removal of such a noise provides the basis for building a blockchain consensus mechanism, which we name Proof of Fuzzy Signature (PoFS). It basically provides a special instance of Proof of Work in which the mining process corresponds to the de-noising process of RSA digital signatures derived from fuzzy keys. This way, the authentication process is delegated to a distributed network and, at the same time, requires executing the useful task of removing noise from fuzzy signatures.