Nagravision S.a.

Nagracard S.a.

Jimmy Cochard

Henri Kudelski

Olivier Brique

Marco Sasselli

Christophe Gogniat

Sébastien Erard

Xavier Carrel

Christian Wirz

Nicolas Courtin

The aim of the present invention consists of reducing the switching time from one reception channel to another. In fact, this reduction will be particularly discernable since the number of different rights stored in a security module of a multimedia unit or decoder is high. When a user selects a service among those proposed by an electronic programs guide, an access control module explores a stored service information table in order to extract an access condition associated to the service. This access condition allows determining an index in a rights table stored in the access control module of a right that fulfills the access condition. The access control module transmits to the security module the index thus determined alone or accompanied by a control message. This index allows the security module to find quickly the right that it compares afterwards with the access condition included in the control message after decryption of the latter.

Method for evaluating user's rights stored in a security module

Example embodiments are directed to a duration computing method in a security module inserted into an apparatus including an internal clock. The apparatus may receive a digital data stream encrypted via control words contained in a control message ECM. The method may include receiving data coming from the internal clock of the apparatus including a current temporal information, storing the data representing the current temporal information in the security module, receiving the control message ECM to decrypt at least one control word, reading previous data representing a previous temporal information at a moment of processing the previous control message ECM, and processing the control message ECM when the current temporal information is temporally ahead of the previous temporal information.

Duration computing method in a security module

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.

Method for access control to conditional access data

The invention concerns a method for controlling access to encrypted data by control words (CW), said control words being received by a security module in control messages (ECM) and returned to a unit operating on (STB) the encrypted data. The method includes the following steps: receiving a first control message (ECM) comprising at least one control word (CW) and a time stamp (TS), receiving a second control message (ECM) consecutive to the first control message (ECM), said second message comprising at least one control word (CW) and a time stamp (TS), determining a duration corresponding to the difference between the time stamps (TS) of the two consecutive control messages (ECM, ECM), if said duration is less than a predefined duration (CP), incrementing an error counter (CE), and if said duration is not less than said predefined duration, decrementing said error counter (CE), returning the control word (CW) to the operating unit (STB) after a waiting time depending on the value of the error counter (CE).

Method and device for controlling access to encrypted data

The objective of the present invention is to propose an accounting method of the consumption of transmitted services per time unit to a decoder in a system implementing a content encrypted by control words, the latter being modified according to a period named crypto-period. This method consists in verifying if the time-current (TC) is comprised in a time variable (Rdate) representative of the authorisation time of use of the service and, if this is the case, decrypting and returning the control words to the decoder, and if it is not the case, debiting an amount (CT) corresponding to a time of use (AT) and recharging the time variable (Rdate) with a corresponding time.

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Attalens, Switzerland

Jimmy Cochard