Cryptographic authentication process

A cryptographic authentication method including a first step a) during which a first entity (A) to be authenticated sends an authenticator second entity (B) a message protected by a cryptographic algorithm and a secret key (KS),

• which method is characterized in that:
• it includes a second step b) during which the second entity (B), after receiving said message, carries out an operation selected from the group comprising:
• completely verifying the authentication of the received protected message by means of said cryptographic algorithm and a verification key (KV),
• delaying complete verification of the authentication of said protected message,
• partly verifying the authentication of the received protected message by means of said cryptographic algorithm and said verification key (KV),
• partly verifying the authentication of the received protected message by means of said cryptographic algorithm and said verification key (KV) and completing the verification subsequently, and
• omitting to verify the authentication of said protected message,
• and in that one of said operations is chosen as a function of the degree of certainty that the second entity (B) wishes to obtain as to the authentication of the first entity (A) and is concealed from the first entity (A).