System and methods for transmitting encrypted data with encryption key
AssigneeNagra Thomson Licensing
InventorsJean-Luc Dauvois, Michel Maillard
Life of this patent
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Abstract
A method for transmitting information between a transmitter station and a plurality of receiving stations in which encrypted information is transmitted from the transmitter station to the receiver station with a first key and at least a control message bearing a second key. The first key used for decryption is restored in each receiving station from the second key and from at least one datum selected from a set of data available in the receiving stations, according to a selection command periodically transmitted between the transmitting station and the receiving station. Such a system may find particular application to pay television.
Claims17
A method for transmitting information between a transmitting station and at least one receiving station, comprising:
- transmitting information encrypted with a first key and at least a message bearing a second key, from the transmitting station to the at least one receiving station, and
- decrypting encrypted information in the at least one receiving station using one selected from a group consisting of a rebuilt version of the first key and a key substantially identical to the first key,
- wherein the one of the rebuilt first key and the key substantially identical to the first key that is used to decrypt the encrypted information is generated in the receiving stations using the second key and at least one datum selected from a set of data available in the receiving stations,
- wherein the at least one datum is selected according to a selection command periodically transmitted between the transmitting station and the receiving stations, wherein the selection command comprises a pointer referencing at least one memory address location of the at least one datum used to generate the one of the rebuilt first key and the key substantially identical to the first key.
A system for transmitting information between a transmitting station and at least one receiving station comprising:
- the transmitting station comprising at least one information encryption device with a first key and configured to transmit encrypted information that is encrypted using the first key;
- and
- the at least one receiving station configured to receive transmitted encrypted information, wherein the at least one receiving station comprises:
- a decryption device configured to decrypt the transmitted encrypted information using one of a rebuilt version of the first key and a key substantially identical to the first key, and
- means for generating the one of the rebuilt version of the first key and the key substantially identical to the first key using a second key transmitted from the transmitting station and at least one datum selected from a set of stored data,
- wherein the at least one datum is selected according to a selection signal transmitted by the transmitting station, wherein the selection command comprises a pointer referencing at least one memory address location of the at least one datum used to generate the one of the rebuilt first key and the key substantially identical to the first key.
A receiving station for an information transmission system able to receive information encrypted by a first key, at least one message containing a second key and a selection signal, the receiving station comprising:
- a decryption device to decrypt the encrypted information, wherein the encrypted information is decrypted using one of a rebuilt version of the first key and a key substantially identical to the first key, and
- means for generating the rebuilt version of the first key using the second key and at least one datum selected from a set of stored data,
- wherein the at least one datum is selected according to the received selection signal, wherein the selection command comprises a pointer referencing at least one memory address location of the at least one datum used to generate the one of the rebuilt first key and the key substantially identical to the first key.
Dependencies are inferred from the claim text.