Abstract: In a method for authenticating a user, a device accesses a key and an initial vector. The vector is generated by using a first algorithm, a reference vector and reference user authentication data. The device accesses data and provided user authentication data. The device generates an intermediary vector by using a second algorithm, the initial vector and the user authentication data. The device generates a cryptogram by using a third algorithm, the key, the intermediary vector and the data. A server receives a request for authenticating a user accompanied with the cryptogram and the data. The server accesses the key and the reference vector. The server generates a reference cryptogram by using the third algorithm, the key, the reference vector and the data. The server verifies whether the reference cryptogram matches the cryptogram. If the reference cryptogram matches the cryptogram, the server authenticates the user.