Method and apparatus for encrypted data stream transmission
AssigneeCanal+ Societe Anonyme
InventorsMichel Maillard, Christian Benardeau, Jean-Luc Dauvois
Life of this patent
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Abstract
A method and apparatus for the transmission and reception of scrambled data is disclosed. In some embodiments, the method and apparatus includes transmitting a scrambled data stream to a decoder, sending the scrambled data stream to a portable security module inserted in the decoder, descrambling the scrambled data stream, encrypting a descrambled data stream, and using the encrypted data stream to the decoder, decrypting the encrypted data stream, and using the decrypted data stream.
Claims23
A method of transmission and reception of a scrambled data stream comprising:
- transmitting a scrambled data stream to a decoder;
- sending the scrambled data stream to a portable security module inserted in the decoder;
- descrambling the scrambled data stream;
- encrypting a descrambled data stream;
- sending the encrypted data stream to the decoder;
- decrypting the encrypted data stream;
- and
- using the decrypted data stream.
A method as claimed in 3 in which the decoder identity value is encrypted by a personalised key known to the security module, the encrypted decoder identity value being stored in the decoder during manufacture for communication to the security module upon insertion of the security module in the decoder.
A method as claimed in 7, in which the second key held by the decoder is encrypted by a third key before communication to the decoder, the decoder possessing the corresponding third key so as to hereby decrypt and verify the second decoder key.
A method as claimed in 14 in which the first encrypted data stream is further scrambled at the point of transmission, descrambled in the security module and then passed in its first encrypted form to the decoder.
A method as claimed in 1 in which the data stream passed in encrypted form between the security module and decoder comprises audiovisual data.
A method as claimed in 1 in which the data stream passed in encrypted form between the security module and decoder comprises a control word stream, the control word stream once decrypted by the decoder being thereafter used by the decoder to descramble associate scrambled audiovisual data.
A method as claimed in 1 in which the scrambled data stream is transmitted as part of a television broadcast.
A method of transmission and reception of a scrambled data stream comprising:
- transmitting a scrambled data stream to a decoder;
- sending the scrambled data stream to a portable security module inserted in the decoder;
- descrambling the scrambled data stream;
- encrypting a descrambled data stream at a point of transmission using a first encryption key, wherein the first encryption key is dependant upon a variable known to both a transmitter and a decoder;
- sending the encrypted data stream;
- decrypting the encrypted data stream using an equivalent of the first encryption key and the variable;
- and
- using the decrypted data stream.
Dependencies are inferred from the claim text.