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

摘要

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.