Patent ID: RE42044

Claim:
A system for transmission and recording of digital data, comprising: a transmission means adapted to : prepare and transmit at least one a first control word encrypted by a first key together with a first title of digital data scrambled by that the first control word; separately prepare and transmit a first message comprising the first key and first credit information, wherein the first message is encrypted by a second key; prepare and transmit a second control word encrypted by a third key together with a second title of digital data scrambled by the second control word; and separately prepare and transmit a second message comprising the third key and second credit information, wherein the second message is encrypted by a fourth key; a digital recording device comprising an access control unit and adapted to : receive the first and second transmitted messages, encrypted by the second and fourth keys, comprising the first key and the first credit information as well as the third key and the second credit information; receive and record , on a digital support , the transmitted scrambled first title of digital data together with the encrypted control word , the digital recording device including an and the transmitted scrambled second title of digital data together with the second encrypted control word; the access control unit comprising a credit unit and adapted to : use the second key to decrypt the first message and obtain the first key; decrypt the first encrypted control word and using the decrypted first key; thereafter descramble the scrambled first title of digital data during playback , wherein said access control module comprises a ; use the fourth key to decrypt the second message and obtain the third key; decrypt the second encrypted control word using the decrypted third key; and thereafter descramble the scrambled second title of digital data during playback; and the credit unit adapted to : decrypt the first encrypted message to obtain the first key and the first credit information; decrypt the second encrypted message to obtain the third key and the second credit information; and use the first and second credit information to control a total number of recordings made capable of being recorded by the digital recording device , wherein recording the first title of digital data, using the first credit information, results in decrementing the total number of recordings, and wherein recording the second title of digital data, using the second credit information, results in further decrementing the same total number of recordings held by the recording device .