Method for transmitting cryptographic data between a client device and a server, based on a message held by the client device, the client device holding a secret element (PIN') and holding an authentication token (B, C) that has been generated beforehand when enrolling with the server, the server holding previous sending context data corresponding to a previous communication with the client device, the transmission method comprising steps, executed by the client device, of: - computing a nonce (m), the nonce (m) being a function of the message and being a function of non-random security information (cpt) known to the client device, said security information comprising at least one sending context datum in relation to the message, - transmitting a datum dependent on the computed nonce (m) to the server, - transmitting a datum dependent on the authentication token (B, C) to the server, - generating a proof of knowledge of a secret (s) based on the secret element (PIN') and on the basis of the nonce (m), the proof of knowledge of a secret (s) being constructed so as to prove knowledge of the secret element (PIN') without disclosing the secret element (PIN'), and transmitting said proof of knowledge to the server, such that the server is able to check the validity of the proof of knowledge of a secret (s), check the possession of the authentication token (B, C), correlate the sending context datum in relation to the message with the previous sending context data in order to establish a potential inconsistency, and decrypt the message. the client device holding a secret element (PIN') and holding an authentication token (B, C) that has been generated beforehand when enrolling with the server, the server holding previous sending context data corresponding to a previous communication with the client device, the transmission method comprising steps, executed by the client device, of: - computing a nonce (m), the nonce (m) being a function of the message and being a function of non-random security information (cpt) known to the client device, said security information comprising at least one sending context datum in relation to the message, - transmitting a datum dependent on the computed nonce (m) to the server, - transmitting a datum dependent on the authentication token (B, C) to the server, - generating a proof of knowledge of a secret (s) based on the secret element (PIN') and on the basis of the nonce (m), the proof of knowledge of a secret (s) being constructed so as to prove knowledge of the secret element (PIN') without disclosing the secret element (PIN'), and transmitting said proof of knowledge to the server, such that the server is able to check the validity of the proof of knowledge of a secret (s), check the possession of the authentication token (B, C), correlate the sending context datum in relation to the message with the previous sending context data in order to establish a potential inconsistency, and decrypt the message. - computing a nonce (m), the nonce (m) being a function of the message and being a function of non-random security information (cpt) known to the client device, said security information comprising at least one sending context datum in relation to the message, - transmitting a datum dependent on the computed nonce (m) to the server, - transmitting a datum dependent on the authentication token (B, C) to the server, - generating a proof of knowledge of a secret (s) based on the secret element (PIN') and on the basis of the nonce (m), the proof of knowledge of a secret (s) being constructed so as to prove knowledge of the secret element (PIN') without disclosing the secret element (PIN'), and transmitting said proof of knowledge to the server, such that the server is able to check the validity of the proof of knowledge of a secret (s), check the possession of the authentication token (B, C), correlate the sending context datum in relation to the message with the previous sending context data in order to establish a potential inconsistency, and decrypt the message.