Patent ID: 8615650

Claim:
A method for deciphering control words for a first terminal and at least one second terminal, said first terminal and said at least one second terminal being mechanically and electronically independent of one another, said method comprising causing said first terminal to transmit a first cryptogram to a control-word server, causing said at least one second terminal to transmit a second cryptogram to said control-word server, causing said control-word server to decipher said first cryptogram to obtain a first control word for enabling descrambling of first multimedia content broadcast on a first channel, causing said control-word server to decipher said second cryptogram to obtain a second control word for enabling descrambling of second multimedia content broadcast on a second channel simultaneously with said first multimedia content, causing said control-word server to transmit said first control word to said first terminal, causing said control-word server to transmit said second control word to said at least one second terminal, causing said control-word server to also transmit said second control word to said first terminal, said second control word being obtained by deciphering said second cryptogram transmitted by said second terminal before said first terminal executes a channel change by changing descrambled channels in passing from said first channel to said second channel, and in response to said channel change, causing said first terminal to execute a search to determine whether said second control word has already been transmitted in advance by said control-word server before said channel change, and if said control word has been transmitted in advance, causing said first terminal to immediately start descrambling said second multimedia content broadcast on said second channel with said second control word, said second control word having been transmitted in advance.