Method for carrying out a transaction, corresponding terminal, server and computer program

1. A method implemented between a communications terminal of a user, a digital identity card and a server for processing a transaction of the communications terminal, the transaction being a payment transaction involving use of payment data provided by the communications terminal of the user during execution of the transaction, wherein the method comprises the following acts:

sending, through a near-field communication (NFC) link by a processor of the communications terminal, a request for a user identification certificate to the digital identity card in the possession of the user, the request including the payment data, the payment data comprising a name, a number, and a card verification value (CVV);

generating, by the digital identity card, the requested user identification certificate, the generating by the digital identity card comprising, generating, using a private key, a digital signature of said name, said number, and said CVV obtained from the digital identity card, the private key being kept only by the digital identity card;

receiving, by the processor of the communications terminal from the digital identity card through the NFC link, the generated user identification certificate;

inserting, by the processor of the communications terminal, said generated user identification certificate into a transaction data structure,

transmitting, by the processor of the communications terminal, the inserted transaction data structure to said server;

decrypting, by the server, the digital signature of said name, said number, and said CVV of the received inserted transaction data structure using a public key of the digital identity card previously transmitted to the server;

comparing, by the server, said decrypted name, said decrypted number, and said decrypted CVV of the inserted transaction data structure with an expected transaction certificate in possession of said server;

determining, by the server, that said decrypted name, said decrypted number, and said decrypted CVV match the expected transaction certificate;

receiving, by the processor of the communications terminal, a piece of data representing validation of the transaction by said server, the validation of the transaction representing said determined match; and

in response to receiving said piece of data, requesting, by the processor of the communications terminal, the server to implement the transaction through a communications network.

2. The method according to claim 1 , wherein the method furthermore comprises:

a preliminary act of determining a certification parameter value, said certification parameter being related to said transaction; and

inserting the certification parameter value into the request for obtaining a user identification certificate.

3. The method according to claim 2 , wherein the certification parameter belongs to the group consisting of:

a creation function parameter for creating said user identification certificate;

a value representing a merchant's identifier;

a value representing a communications terminal identifier;

a value representing the transaction;

a value representing a date and/or a time of the transaction.

4. The method according to claim 1 , wherein the inserting said user identification certificate into a transaction data structure comprises selection, from among a plurality of available fields, of a specific existing field.

5. The method according to claim 4 , wherein the specific field is a field dedicated to reception of a card verification value.

6. The method according to claim 2 , wherein the certification parameter comprises a piece of data representing an identifier of said communications terminal and a piece of data representing a time of the transaction.