| 摘要 |
A method is disclosed for access control to conditional access data in a multimedia unit comprising at least one security module. This process includes: reception by the multimedia unit of a control message ECM containing at least one control word cw; transmission of this message ECM to said security module, this control message being associated to a message decryption right; determination of a validity date of the ECM control message decryption rights associated to said security module; determination of the present date; comparison of the present date with the expiration date of the decryption rights and determination of whether the present date is prior to the expiration date. In the affirmative case, decryption of the control message ECM and sending of the control word cw to the multimedia unit occurs In the negative case, reading of a value contained in a counter of the security module and comparison of this value occurs, to determine whether this value is comprised within a range authorizing decryption. Further, in the affirmative case, modification of the value of the counter according to a pre-established rule, and decryption of the control message ECM and sending of the control word cw to the multimedia unit also occurs. Finally, in the negative case, access to the conditional access data is blocked. |
