Patent ID: 8099778

Claim:
A method for access control to conditional access data in a multimedia unit including at least one external security module, the method comprising: receiving, by the multimedia unit, at least one control message containing at least one control word; transmitting the control message to said at least one external security module, the control message being associated to a message decryption right; determining a validity date of the control message decryption rights associated to said external security module; determining the present date; and comparing the present date with the validity date of the decryption rights and determining whether the present date is prior to the validity date, wherein when the present date is prior to the validity date, the method includes, decrypting the at least one control message in the external security module and sending the control word to said multimedia unit from the external security module; and when the present date is not prior to the validity date, the method includes reading a value stored in a counter of the external security module and comparing the stored value with a range of values authorizing decryption, and determining whether the compared value is within the range, wherein when the stored counter value is within the authorized range, the method includes, modifying the value of the counter according to a desired rule, decrypting the at least one control message and sending the at least one control word from the external security module to said multimedia unit; and when the stored counter value is not within the authorized range, the method includes blocking access to said conditional access data, and wherein the at least one external security module is immediately operational to grant access to the conditional access data when connected to the multimedia unit without receiving an activation message from a management centre.