Patent ID: 8885825
Filing Date: 2014-11-11
Classification: H04L,H04N

Abstract:
1. A method of establishing a cryptographic session key which is common to a network head which transmits scrambled multimedia signals and a receiver of those scrambled multimedia signals capable of unscrambling the signals received by means of a check word, the method comprising: recognizing a first connection of the receiver to the network head through a telecommunications network via any local loop of a plurality of local loops within the telecommunications network that are each uniquely identified among the plurality of local loops by an identifier of the local loop and each directly connected, at a first end of the local loop, to a respective termination location installed at a premises of a subscriber to the telecommunications network and, at a second end of the local loop, to at least one piece of network equipment that is part of a center for connection to the telecommunications network managed by a telecommunications service provider and with limited or restricted physical access by subscribers to the telecommunications network; upon the receiver connecting to the network head in the first connection, automatically obtaining the identifier of the local loop via which the receiver is connected to the network head by way of a connection to the respective termination location connected to the local loop at the first end of the local loop using pieces of information provided by the at least one piece of network equipment connected to the local loop at the second end of the local loop via which the receiver is connected to the network head; verifying that the identifier obtained for the local loop via which the receiver is connected to the network head in the first connection corresponds to a previously obtained identifier acquired prior to the receiver connecting to the network head in the first connection of a local loop of the plurality of local loops for which the respective termination location connected to the local loop identified by the previously obtained identifier at the first end of the local loop is located at the premises of a subscriber to the telecommunications network associated with the receiver to authenticate the receiver; and upon the receiver being authenticated, completing construction of the cryptographic session key only if the receiver has been correctly authenticated by verifying that the identifier obtained for the local loop via which the receiver is connected to the network head in the first connection corresponds to the previously obtained identifier, wherein the previously obtained identifier is acquired using pieces of information provided by the subscriber associated with the receiver during a subscription operation in which a determination is made that the receiver must be connected to the respective termination location installed at the premises of the subscriber for the receiver to be authenticated; and wherein: during the subscription operation, the network head generates a unique activation code which is associated, in the network head, with the previously obtained identifier acquired during the subscription operation, prior to verification that the identifier obtained for the local loop via which the receiver is connected to the network head in the first connection corresponds to the previously obtained identifier acquired prior to the receiver connecting to the network head in the first connection being performed, the receiver obtains the activation code, upon the first connection being established with respect to the network head, the receiver transmits the activation code to the network head via the network, and during verification that the identifier obtained for the local loop via which the receiver is connected to the network head in the first connection corresponds to the previously obtained identifier acquired prior to the receiver connecting to the network head in the first connection, the network head uses the activation code received from the receiver to establish correspondence between the previously obtained identifier acquired prior to the receiver connecting to the network head in the first connection and the identifier obtained for the local loop via which the receiver is connected to the network head in the first connection.