Viaccess

Erwann Magis

Gilles Dubroeucq

Anthony Chevallier

Stéphane Lanfranchi

A method of transmitting control words to terminals that are mechanically and electronically independent of one another includes transmitting, to a terminal, an absent control word in response to a request from the terminal that contains a cryptogram corresponding to the absent control word, for the terminal, selectively determining a number of additional control words to be transmitted to the terminal as a function of a probability that security of the additional control words is compromised, and transmitting, to the terminal, in addition to the absent control word, the determined number of additional control words to enable the terminal to descramble at least one additional cryptoperiod of the multimedia content in addition to the cryptoperiod of the multimedia content that can be descrambled using the absent control word.

Methods for decrypting, transmitting and receiving control words, recording medium and control word server to implement these methods

A method for deciphering control words for mechanically and electronically independent terminals includes causing first and second terminals to transmit a first and second cryptograms to a control-word server, causing that server to decipher them to obtain first and second control words for enabling descrambling of first and second multimedia content broadcast simultaneously on respective first and second channels, causing the server to transmit the control word to the respective terminals, the second control word obtained by deciphering the second cryptogram before the first terminal executes a channel change, and in response to the channel change, causing the first terminal to search to determine whether the second control word has already been transmitted in advance by the server before the channel change, and if the control word has been transmitted in advance, causing the first terminal to immediately start descrambling the second multimedia content with the second control word.

Control-word deciphering, transmission and reception methods, recording medium and server for these methods

A method for access control to a digital scrambled content distributed to a set of installed reception terminals including one master terminal and at least one slave terminal dependent on the master terminal. In the method the slave terminal systematically or occasionally returns at least one item of information about the access condition to the master terminal through a point-to-point link, to enable the master terminal to control access of the slave terminal to the content.

Growing community of inventors

Paris, France

Erwann Magis