Abstract: The invention relates to pairing a slave device with a master device, for example decoders in a conditional access system. There is provided a security module that stores a device state that indicates whether a decoder shall be a master or a slave decoder. There is also provided a method in a conditional access system of providing a device with a device state stored on a security module. It is detected that the security module is in connection with the device and the device state is transferred from the security module to the device. There is further provided a method of pairing a slave device with a master device. The slave device asks the master device to identify itself, the master device returns an identification, and if the slave device has not yet been paired with a master device, it checks the identity of the master device and, if the identity is verified pairs with the master device. There is also provided a first, slave, device for pairing with a second, master, device.

Abstract: The invention relates to a device for preventing illegal exportation of a content protected by a global copy protection system to a local copy protection system. According to the invention, each content liable to be exported contains a unique identifier and the device comprises a table for storing unique identifiers of all contents that have already been exported through said device. The invention also relates to a method for recording a content received by such a device. This method comprises the steps consisting, if the copy is to be made for a local copy protection system, in checking whether the unique identifier of said content is contained in the table of said device; and should said checking be positive, in preventing the recording; andshould said checking be negative, in recording the content and storing said unique identifier in said table.

Abstract: The invention relates to the protection by firewall of a domestic community of interconnectable appliances. The invention allows distributed and totally decentralized management of the firewall policy, implemented at the level of each appliance, which is consistent and adapts dynamically to the changes occurring within the domestic network. We shall speak of ubiquitous firewalls.

Abstract: The invention relates to a local digital network comprising: at least one source device intended to broadcast data over the network; and at least one receiver device intended to receive said data. The source device uses a network active encryption key to encrypt data liable to be broadcast in the network and the receiver device contains: a network active decryption key for decrypting data encrypted using said active encryption key and at least one decryption key of the network for decrypting data encrypted with the aid of an encryption key used previously in the network. The invention also relates to the installing of new devices in such a network as well as the sending of data from a source device to a receiver device.

Abstract: The invention relates to a method whereby it can be checked whether data received by a receiver has been sent by a transmitter authorized by a trusted third party, the transmitter and the receiver being connected to a digital network. An identifier is associated with the data sent by the transmitter and, on receipt of the data by the receiver, the receiver generates a random number and diffuses the same on the network. The transmitter that receives said random number calculates a response by applying a first function to the random number and to the identifier, and sends said response to the receiver which verifies the response received by applying a second function to the response received, the random number and the identifier. The first function is delivered first to the transmitter by the trusted third part, and the second function is a function for checking the result of the first function which is delivered first to the receiver by the thrusted third party.

Abstract: To transmit digital data representing a content from a source (1) to a receiver (2) through a digital communication channel, the data being scrambled by at least one control word (CW), the method includes the following steps. The source generates an encryption key (KCW) which it stores temporarily. It encrypts the control word with the encryption key and transmits to the receiver the scrambled digital data (3) and the encrypted control word (4), the latter being transmitted through an encrypted communication channel (21). The receiver then performs an operation (22) of authentication of the source. When the source is authenticated by the receiver, it transmits the encryption key (KCW) to it. The receiver then decrypts the control word and descrambles the data so as to present them to a user. The encryption key is then erased from the memories of the source and the receiver when the content has been entirely transmitted.

Abstract: The communication network comprises a device of a first type (1) furnished with a source of data to be broadcast over the network and at least one device of a second type (2) intended to receive the said data.

Abstract: The invention concerns a device for reading digital data (10) receiving data representing a content designed to be connected to a digital home network. It comprises: first means for encrypting (13) data in accordance with a protection mode specific to a line whereby the device is to be connected to another digital network device, the encrypted data being in that case supplied to a first output (S1); and second means for encrypting (14) data in accordance with a mode specific to the home network, the encrypted data being in that case supplied to a second output (S2). The invention also concerns a device for recording and restoring digital data designed to be connected to said reading device (10).