BigPatents India

The invention concerns a method and a device for controlling access to data encrypted by control words (CW), these control words being received in control messages (ECM) by a security module and returned to a processing unit (STB) for encrypted data. The method includes the following steps: - reception of a first control message (ECM1) comprising at least one control word (CW) and a time stamp (TS), - reception of a second control message (ECM2) consecutive to the first control message (ECM1), this second message comprising at least one control word (CW) and a time stamp (TS), - determination of a time duration corresponding to the difference between the time stamps (TS) of the two consecutive control messages (ECM1, ECM2), - if this time duration is lower than a predefined time duration (CP), incrementation of an error counter (CE), - if this time duration is equal to or greater than said predefined time duration, decrementation of said error counter (CE), - returning of the control word (CW) to the processing unit (STB) after a waiting time that depends on the error counter (CE) value. No. of Pages : 29 No. of Claims : 16