Patent ID: 7769171

Claim:
A method for transmitting digital data in a local network including one or more members constituted by a sub-network having at least one first multimedia unit having content storage means and at least one second multimedia unit configured to restore the content, said first multimedia unit being connected to a broadcasting server of encrypted digital audio/video data, to a license server and to the second multimedia unit, each unit of the sub-network having a security module including a personal key of the sub-network, a public key corresponding to a private key pertaining to the license server and a network key, said method comprising: transmitting, by said broadcasting server, encrypted data forming a content to said license server; attributing, by said license server, an identifier to said content; receiving and decrypting, by said first multimedia unit, said encrypted data forming said content; re-encrypting using a random key, by said first multimedia unit, the content previously decrypted; forming, by said first multimedia unit, an authorization block including at least one information block identifying said content, a signature block of said license server and said random key encrypted with said personal key of said sub-network; transmitting, by said first multimedia unit, said re-encrypted content accompanied by said authorization block to said second multimedia unit; decrypting, by said second multimedia unit, said authorization block; extracting, by said second multimedia unit, said random key to be used for decrypting said content; verifying, by said second multimedia unit, the authenticity of said content using said information block and said signature block of said license server; and decrypting said content using said random key.