Implementation process for the use of cryptographic data of a user stored in a data base

A method for the implementation, via a security module (SM), of a user U's cryptographic data (Usk) stored in a database (BD), by means of a terminal (T) that the user uses and which communicates with the security module (SM) via a communication network (R), the method comprising the following steps and sequences:

• an authentication sequence comprising the following successive steps:
• mutual authentication between the security module (SM) and the terminal (T), based on an asymmetric cryptographic protocol, establishing a secure channel between the security module (SM) and the terminal (T);
• in the event of a positive mutual authentication of the security module and the terminal;
• mutual authentication of the security module and the user based on an asymmetric cryptographic protocol;
• in the event of a positive mutual authentication between, on the one hand, the security module and the terminal and, on the other hand, the security module and the user:
• the security module (SM) obtains the user's cryptographic data (Usk) from the database (BD), the cryptographic data being stored in the database (BD) in encrypted form by means of at least a first encryption key (KDF(Tsk,PIN)) established from at least one secret key from the terminal (Tsk) and the user's authentication element (PIN) and by means of a second encryption key (SMk) specific to the security module (SM), encryption by means of the second encryption key taking place after encryption by means of the first encryption key;
• the terminal calculates the first encryption key (KDF(Tsk,PIN));
• the terminal sends the first encryption key to the security module via the secure channel;
• and
• implementation of the user's cryptographic data (Usk) by the security module (SM) after decryption, by the security module (SM) of the user's cryptographic data (Usk) at least first of all by means of the second encryption key (SMk) and then the first encryption key (KDF(Tsk,PIN)).