LOCAL CONDITIONAL ACCESS METHOD FOR MOBILE EQUIPMENT

摘要

The invention relates to a conditional method for accessing an flow of digital data encrypted with at least one first control word CW and broadcast via a transmitter (E1, E2) of a broadcast network (NET1) to at least one item of mobile equipment (EM1, EM2) also connected via a mobile communications network (NET2) to a management center (CG). The broadcast flow contains control messages ECM encrypted with a transmission key TK and comprising a second control word CW' obtained by encrypting the first control word CW with a local key KL. The method is characterized in that it comprises the following steps: receiving, via the item of mobile equipment (EM1, EM2), at least one cryptogram over the mobile network (NET2); determining at least one local key KL from the received cryptogram; receiving a control message ECM over the broadcast network (NET1); decrypting said ECM message and obtaining the second control word CW'; decrypting the second control word CW' with the local key (KL) and obtaining the second control word (CW'); decrypting the second control word CW' wit the local key (KL) and obtaining the first control word CW, and; decrypting the data of the flow with the first control word CW.