An authentication method for authenticating a client with a service over a network of peers, comprises: storing encrypted enrolled authentication data for the client in a storage that is accessible by means of an access privilege; storing a decryption clue for the encrypted enrolled authentication data in a client data block chain; receiving, by the network, authentication information from the client; generating, by a server connected to the client, a decryption key according to a contract involving the decryption clue stored in the client data block chain; receiving, by the network, the encrypted enrolled authentication data from the storage; decrypting, by the network, the encrypted enrolled authentication data using the decryption key to obtain decrypted enrolled authentication data; comparing, by the network, the decrypted enrolled authentication data with the authentication information received from the client for obtaining a match score based on a consensus of the peers of the network; and storing the match score and a hash of a client identifier in a service data block chain.