Method and system of copy protection of information

Abstract

The invention relates to a method of copy-protection of information stored on an information carrying medium. The method allows a reading device (e.g. a DVD drive) and an application device (e.g. an MPEG decoder) to exchange copy-protection information regarding the information carrying medium (e.g. an optical record carrier like a CD or DVD) and the content on that medium. The method is cryptographically secure, taking into account the situation where reading device and application device are connected to an open bus in a personal computer. In view of the high-volume nature of the drive, the method can be implemented cheaply. The inventive method is robust against a so-called man-in-the-middle attack. The invention relates also to a method of exchanging copy-protection information, to a copy-protection system and to devices for carrying out these methods, in particular a reading device, an application device and a device for playback and/or recording of information.

1 . A method of copy protection of information stored on an information carrying medium to be read from a reading device and transmitted to an application device for playback and/or recording, wherein the reading device continuously derives and reports to the application device a first characteristic of the content of the information transmitted from the reading device to the application device, wherein the application device continuously derives and reports back to the reading device a second characteristic of the content of the information received by the application device, the second characteristic being different than the first characteristic and being derived independent of the first characteristic and wherein the characteristics are verified by comparison and wherein the result of the comparison is used to stop the transmission, playback and/or recording of information in case of a mismatch of the characteristics.  
   
   
       2 . A method as claimed in  claim 1 , characterized in that summaries of the transmitted and of the received information are used as characteristics.  
   
   
       3 . A method as claimed in  claim 1 , characterized in that summaries of selected parts of the transmitted and of the received information are used as characteristics.  
   
   
       4 . A method as claimed in  claim 3 , characterized in that the selection of the parts of information to be summarized is based on a secret shared between the reading device and the application device.  
   
   
       5 . A method as claimed in  claim 3 , characterized in that the information is stored in a plurality of sectors in MPEG-format on an optical record carrier, especially on a DVD, and that the selection of sectors of information be summarized is based on the value a SCR-base-field of the sectors.  
   
   
       6 . A method as claimed in  claim 1 , characterized in that the characteristics are exchanged between the reading device and the application device together with physical and/or watermark-information of the information carrying medium.  
   
   
       7 . A method of exchanging copy protection information regarding an information carrying medium between a reading device and an application device, wherein the copy protection information comprises a first characteristic of the content of the information transmitted from the reading device to the application device derived by the reading device and a second characteristic of the content of the information received by the application device derived by the application device, the second characteristic being different than the first characteristic and being derived independent of the first characteristic, and wherein the characteristics are verified by comparison and wherein the result of the comparison is used to stop the transmission, playback and/or recording of information in case of a mismatch of the characteristics.  
   
   
       8 . A copy protection system for a copy protection of information stored on an information carrying medium having a reading device for reading the information from the information carrying medium and an application device for any application, especially for playback and/or recording, of the information received from the reading device, wherein the reading device comprises means for deriving and continuously reporting to the application device a first characteristic of the content of the information transmitted to the application device, wherein the application device comprises means for deriving and continuously reporting to the reading device a second characteristic of the content of the information received by the application device, the second characteristic being different than the first characteristic and being derived independent of the first characteristic, and the reading device and/or the application device further comprise a verifying unit for verifying the characteristics by comparison, wherein the result of the comparison is used to stop the transmission, playback and/or recording of information in case of a mismatch of the characteristics.  
   
   
       9 . A reading device for reading information from an information carrying medium and transmitting it to an application device for playback and/or recording comprising a reader report unit for continuously deriving and reporting to the application device a first characteristic of the content of the information transmitted to the application device and a verifying unit for receiving a second characteristic of the content of the information received by the application device and continuously reported from the application device to reading device and for verifying the characteristics by comparison, the second characteristic being different than the first characteristic and being derived independent of the first characteristic, and wherein the result of the comparison is used to stop the transmission, playback and/or recording of information in case of a mismatch of the characteristics.  
   
   
       10 . An application device for receiving information from a reading device for playback and/or recording comprising an application report unit for continuously deriving and reporting to the reading device a first characteristic of the content of the information received by the application report unit and a verifying unit for receiving a second characteristic of the content of the information transmitted from the reading device to the application device continuously reported from the application report unit and for verifying the characteristics by comparison, the second characteristic being different than the first characteristic and being derived independent of the first characteristic, and wherein the result of the comparison is used to stop the transmission, playback and/or recording of information in case of a mismatch of the characteristics.  
   
   
       11 . A device for playback and/or recording of information stored on an information carrying medium comprising a reading device according to  claim 9 .  
   
   
       12 . A device for playback and/or recording of information stored on an information carrying medium comprising an application device according to  claim 10.