Method for securing data transmission, and corresponding system

A method for secure transmission of data between a mobile terminal and an acceptance server, the mobile terminal being configured to communicate via a communication channel with a remote transciphering server comprising a transactional black box, the method being implemented by the transciphering server and comprising:

• generating a first key, the first key being variable;
• transmitting, via the communication channel, to the mobile terminal the first key;
• receiving, via the communication channel, from the mobile terminal, the data encrypted by the mobile terminal with the first key;
• decrypting, by the transactional black box, with the first key, the data encrypted with the first key;
• encrypting the data, by the transactional black box, with a second key;
• transmitting, via the communication channel, to the mobile terminal, of the data encrypted with the second key, the second key being shared between the transciphering server and the acceptance server, and not being transmitted to the mobile terminal.

A mobile terminal for a secure transmission of data with an acceptance server, the mobile terminal comprising:

• hardware;
• and
• at least one memory storing software, which together with the hardware configures the mobile terminal to secure transmission of the data between the mobile terminal and the acceptance server, the mobile terminal being configured to communicate via a communication channel with a remote transciphering server, and to communicate with the acceptance server, the securing transmission comprising:
• receiving, via the communication channel, a first key generated by the transciphering server, the first key being variable;
• encrypting the data with the first key;
• transmitting, via the communication channel, the data encrypted with the first key to the transciphering server;
• receiving, via the communication channel, the data encrypted with a second key by a transactional black box of the transciphering server;
• and
• transmitting to the acceptance server the data encrypted with the second key, the second key being shared between the transciphering server and the acceptance server and not being received by the mobile terminal.