| 摘要 |
<p>The invention concerns a protocol for accessing scrambled data, the access control being carried out on the basis of access control messages (ECM). It consists in assigning (A) to each access control message a serial number (Tj) verifying a non-decreasing monotonous function, the messages representing a time base constituting of a plurality of elementary time intervals of transmission of successive information quanta, in detecting (B) at each descrambling terminal the serial number of the access control messages, then on request (UR) from the subscriber user, in selecting (C) the serial number of an access control message corresponding to the transmission time of the request, and in constituting a time base origin (Tjo) of the time base and in authorizing (D), (E) access to said scrambled data on the basis of a specific access criterion with reference to said origin (Tjo) and of a time range corresponding to a plurality of elementary time intervals defining a plurality of successive quanta of scrambled data. The invention is applicable to pay-television access control.</p> |
