In order to provide a communication protocol for cryptographic authentication on the basis of at least one cryptographic algorithm, in particular according to the A[dvanced]E[ncryption]S[tandard], by providing at least one random number (PRN′) for at least one first, in particular present, authentication sequence or authentication session (n), and providing at least one further random number (PRN2, PRN3) for at least one further, in particular second or next, authentication sequence or authentication session (n+1), wherein the relevant time for cryptographic authentication is shortened, it is proposed that providing the further random number (PRN2, PRN3) is initialized (p) when, in particular immediately after, successfully performing the authentication in the first authentication sequence or authentication session (n).