Abstract: Method to detect a cloned software to be used on a client user unit communicating with a server for requesting a service by sending a request from the user unit to the server, the latter being connected to a database comprising client records, each of these records comprising at least a tag value (tc) as history of client requests, said method comprising an initialization phase and a operating phase, a) the initialization phase comprising the steps of: defining said tag value (tc) as being equal to an initial random value, then opening a new record storing said tag value (tc) in the database and introducing said tag value into the client user unit, b) the operating phase comprising the steps of: preparing, on the user unit side, a client message for the server comprising said request and a value depending on said tag value (tc), then sending this client message, from the user unit to the server, then checking, on the server side, an access condition by checking if the tag value (tc) of said client message is

Abstract: An electronic unit includes a processor (P), an input-output device (18) and a cryptographic device (14). The unit is directly connected by two-way data transmission (20) set up between the input-output device and the cryptographic device, the electronic unit being integrated in a microcircuit card.

Abstract: A method for monitoring execution of a sequence of data processing program instructions in a security module associated to a multimedia unit connected to a managing center supplying control messages authorizing access to broadcast data streams. The security module comprises a processor for executing the instructions, a memory, and a monitoring module for analyzing the instructions before execution by the processor. The managing center comprises a security module emulator generating reference data sets by executing a sequence of instructions induced by data of a given control message in the program. The reference data sets are appended to control messages sent to the security module. The monitoring module analyzes a sequence of program instructions for determining a check data set which is compared with a reference data set received from the control messages. When the reference and check data sets match, the program continues executing. Otherwise, further control message processing stops.

Abstract: A method for monitoring execution of a sequence of data processing program instructions in a security module associated to a multimedia unit connected to a managing center supplying control messages authorizing access to broadcast data streams. The security module comprises a processor for executing the instructions, a memory, and a monitoring module for analyzing the instructions before execution by the processor. The managing center comprises a security module emulator generating reference data sets by executing a sequence of instructions induced by data of a given control message in the program. The reference data sets are appended to control messages sent to the security module. The monitoring module analyzes a sequence of program instructions for determining a check data set which is compared with a reference data set received from the control messages. When the reference and check data sets match, the program continues executing. Otherwise, further control message processing stops.

Abstract: The invention concerns a method for reproducing digital content including the following steps: receiving (E222) an identifier (Id?) of the digital content from a secure electronic entity; extracting (E226) a digital watermark of the digital content; controlling (E232) the reproduction of the content based on a comparison between the extracted watermark and the identifier. The invention concerns a reproducing device, an electronic entity and related systems.

Abstract: A method for creating a group signature of a message to be implemented by a member of a group in a system, the system including a trust authority, the group including at least the member provided with a secure portable electronic entity including storage elements and computing elements wherein are implanted a cryptographic algorithm. The method includes the following steps: generating via the computing elements a signature of the message using a private key common to the members of the group and integrating a data identifying the group member and a temporal data representing a temporal information of the member's membership to the group and of the date of the signature of the message, the private key common to the members of the group, the identifying data and the temporal data being stored in the storage elements.

Abstract: An exchange of information between a communication entity e.g. a mobile telephone and the operator server upon which it is dependent, in order to carry out authentication operations by exchanging keys and using cryptography algorithms. According to the invention, an algorithm is used, comprising: algorithmic treatments using, as input data, all or part of a random number and operating keys derived from two keys, and a combined treatment using data derived from algorithmic treatments in order to provide results to enable the linkage.

Abstract: A method for making secure execution of a computer program includes the following steps: stacking a predetermined value in a pile of instructions of the program; and stack popping the pile, the stack popping step being adapted, as the case may be, to enable detection of an anomalous execution.

Abstract: A method for making secure execution of a computer programme includes a set of at least one instruction, characterized in that it includes: a first step which consists in calculating and storing, prior to execution of the computer programme, a first signature representing the expected execution of the set of instructions; a second step which consists in calculating and storing, during execution of the set of instructions, a second signature representing the execution of the set of instructions; and a step which consists in detecting an anomaly of execution of the set of instructions from the first and second signatures.

Abstract: An exchange of information between a communication entity e.g. a mobile telephone and the operator server upon which it is dependent, in order to carry out authentication operations by exchanging keys and using cryptography algorithms. According to the invention, an algorithm is used, comprising: algorithmic treatments (35A, 35B) using, as input data, all or part of a random number (FAND) and operating keys (KA, KA2-Kd) derived from two keys (K; Kd), and a combined treatment using data derived from said 10 algorithmic treatments in order to provide results (SRES, K.) enabling the linkage.

Abstract: The invention concerns an electronic unit comprising a processor (P), input-output means (18) and cryptographic means (14), characterized in that it is directly connected by two-way data transmission (20) set up between said input-output means and said cryptographic means, the electronic unit being integrated in a microcircuit card.

Abstract: The invention relates to a process for scrambling video data in the MPEG2 video format as well as to a process for descrambling data scrambled according to the process of the invention. The scrambled video data are the coefficients AC and/or DC arising from the “discrete cosine transform” operation which are associated with at least one block of at least one image coded in INTRA mode. The invention applies to conditional access systems such as, for example, pay television systems.

Abstract: The invention relates to a process for protecting an information item transmitted from a security element to a decoder and a protection system using such a process. The information item is protected by encrypting within the security element the information item to be transmitted to the decoder and by decrypting this information item within the decoder. The invention applies to conditional-access systems.

Abstract: The invention relates to a conditional access system making it possible for a service provider to supply his services solely to users having acquired entitlements to these services.The services supplied by a service provider consist of an item scrambled by control words. To keep these control words secret, they are supplied in messages (MEC) after having been encrypted with an encryption algorithm with key K.According to the invention, one and the same message (MEC) contains the same control word (Cwi) encrypted several times, each encryption (E(Cwi)Kj) of the control word depending on a different encryption key (Kj).The invention applies to any type of conditional access system, be this system either of "off-line" or "on-line" type.

Abstract: The conditional access system of the present invention allows a service provider to supply services, which may be scrambled by a control word, only to those users who have acquired entitlements to these services. The control word is supplied in Entitlement Control Messages (ECM) after having been encrypted using a key. The entitlements of each user are forwarded in Entitlement Management Messages which contain the key. The conditional access system verifies and validates the ECM and EMM prior to processing the control word.

Abstract: The system includes a plurality of decision units, at least one verification unit, and at least one counting unit, the units being functionally and structurally separate from each other. Each decision unit includes means for producing a source information item and an identity information item, and means for enciphering this source information item in such a way as to render it essentially indecipherable by the verification unit but decipherable by the counting unit. The verification unit includes a file which includes the identities of the decision units, means for checking the identity of the decision unit from which an incoming message originates, and means for compiling an anonymous derived message which is essentially devoid of any identity information item decipherable by the counting unit.

Abstract: The process comprises a "pledging" step in which a debtor party transmits to a creditor party a data item which is the image of a pledged data item, and a "commencement" step in which the debtor party transmits the plain pledged data item to the creditor party who can verify pledge consistency. In the pledging step, the debtor party produces a seed applied to a pseudo-random generator to produce a pseudo-random word, combines this pseudo-random word in a one-to-one and reversible manner with the pledged data item to produce a checkword, and transmits the checkword to the creditor party. In the commencement step, the debtor party transmits to the creditor party the seed together with the plain pledged data item.

Abstract: The present invention relates to a method of processing a digital signal of dimension k, in a so-called secure communication system, such that the digital signal (y) at output cannot be deduced from the digital signal (x) at input, consisting in dispatching the digital signal (x) to a device effecting a one-way function.The method includes the following steps:the digital signal (x) at the input is dispatched to a circuit C (1, 2) which gives as output a digital signal (x") of dimension n acceptable to the one-way function;the signal (x") from the circuit C (1, 2) is dispatched to the circuit effecting the one-way function giving as output the digital signal (y).The invention applies in particular to so-called secure communication systems.