Method and system for secured broadcasting of a digital data stream

A system for secured broadcasting of a digital data flow between a technical platform coupled to at least one terminal the system comprising:

• at least one terminal including a chipset comprising a secured memory area which stores a secret key during a production phase of the terminal;
• and
• at least one processor configured to perform the steps of:
• transmitting a scrambled and multiplexed digital data flow with at least one message (ECM) including a control key (CW) encrypted with a channel key (CC);
• descrambling in a secured memory area of the terminal, the scrambled digital data flow from the control key (CW) obtained according to the following substeps:
• sending to the technical platform a request including the identifier (IUi) of the terminal;
• generating a first secret key (CSk) from a cryptographic mechanism using a unique ciphering key (BSKn) and the identifier (IUi) of the terminal, and ciphering said channel key (CC) with the first secret key (CSk) to obtain a ciphered message (eCCk);
• transmitting the ciphered message (eCCk) to the terminal;
• deciphering the ciphered message (eCCk) received by the terminal using the key stored in the terminal during the production phrase of the terminal to obtain the channel key (CC), and
• obtaining the control key (CW) resulting from the deciphering of the message (ECM) from the channel key (CC);
• wherein the generating comprises a substep for identifying a ciphering key index associated with the identifier (IUi) of the terminal and stored within a server for managing rights relating to the contents of the digital data flow;
• and
• determining the ciphering key (BSKn) from a plurality of ciphering keys archived in another server for generating secret keys (CSk), corresponding to the index.