JP4636043B2 - Data reproduction apparatus and data transmission method - Google Patents

Description

The present invention relates to a data reproducing apparatus and a data transmission method for connecting a plurality of digital video equipments via a bus and transferring video data between the plurality of digital video equipments via the bus. It relates to the protection of video data transferred through the network.

  Satellite broadcasting that compresses digital video signals and broadcasts using satellites, digital VTR that compresses video signals and records them on magnetic tape, recording and playback devices that compress digital video signals and record them on optical disks and magneto-optical disks, etc. Various AV devices that handle digital video signals have been developed. A bus for exchanging data and commands using a common protocol between such various AV devices has been proposed. By using such a bus, various AV devices can be easily connected, and operability can be improved by centralized control management such as one-touch dubbing.

  The digital video signal hardly deteriorates even if dubbing is repeated. For this reason, it is feared that copyrights will not be protected when AV equipment that handles such digital video signals becomes widespread. Therefore, various methods for protecting video data have been proposed.

  As one method for protecting video data, for example, it has been proposed to include a flag indicating copy permission / prohibition in data to be transmitted. That is, when sending copy-prohibited data, a copy-prohibit flag is set and data is sent from the transmission side. On the receiving side, the presence / absence of a flag is determined, and recording inhibition is controlled according to the presence / absence of the flag.

  However, the method using such a flag cannot sufficiently protect data in a system in which various AV devices as described above are connected by a bus. That is, even if a flag indicating permission / prohibition of copying is included, video data is transferred as it is on the bus. It can be handled in the same way as transmitting video signals with analog signal lines, so that video data can be recorded while displaying video on the display, and video data can be recorded with multiple recording devices, No destination is specified for data on the bus. Therefore, all the video devices connected on the bus are in a state where the video data on the bus can be taken. Therefore, even if video data including a copy prohibition flag is transferred onto the bus, AV equipment that does not process the flag is in an open state.

Accordingly, an object of the present invention is to connect video data transferred via a bus when a plurality of digital video devices are connected via a bus and video data is transferred between the digital video devices via the bus. It is an object of the present invention to provide a data reproducing apparatus and a data transmission method that can be sufficiently protected.

The present invention is a data reproduction apparatus as an AV device that reproduces data recorded on a recording medium and transmits the reproduced data to another AV device via a bus.
Reproducing means for reproducing data recorded on the recording medium;
Encryption means for encrypting data reproduced by the reproduction means;
Authentication means for exchanging commands with other AV devices for determining whether the other AV devices are authenticated by the data reproducing device;
When it is determined that the other AV device is authenticated based on the exchange of commands, the data encrypted by the encryption unit and the data encrypted by the encryption unit are encrypted with respect to the other AV device. Transmission means for transmitting key information for decrypting data and a command for turning on or off a switch circuit of another AV device ;
Have
The exchange of commands to determine if you are authenticated is
Transmit command information from the data playback device to other AV devices,
The other AV device transmits the authentication information formed based on the key information of the other AV device based on the command information to the data reproducing device,
In the data reproducing apparatus, the authentication information is compared with the predetermined information formed based on the key information of the data reproducing apparatus, and if the authentication information matches the predetermined information, the other AV device uses the data reproducing apparatus. It is done by judging that it is authenticated ,
Authenticated by causing another AV device that has been determined to be authorized to turn on the switch circuit of another AV device to receive the command to turn on the switch circuit of the other AV device. The data reproduction device causes the other AV device determined to receive the data encrypted by the encryption unit and the key information for decrypting the data encrypted by the encryption unit .

The present invention is a data transmission method in which a data reproduction device reproduces data recorded on a recording medium and transmits the reproduced data to another AV device via a bus.
Data playback device
Play the data recorded on the recording medium,
Encrypt the replayed data,
A command for determining whether or not the other AV device is authenticated by the data reproducing device that reproduces data is exchanged between the data reproducing device and the other AV device. The command information is transmitted to another AV device, and the authentication information formed based on the key information of the other AV device based on the command information is transmitted to the data reproduction device. This is performed by comparing the predetermined information formed based on the key information of the device and when the authentication information matches the predetermined information, it is determined that the other AV device is authenticated by the data reproducing apparatus. ,
Based on the exchange of commands, when it is determined that the other AV device is authenticated by the data reproducing apparatus, a command for turning on the switch circuit of the other AV device is transmitted to the other AV device. Then, the switch circuit of the other AV device judged to be authenticated is turned on, and the encrypted data and the key information for decrypting the encrypted data are transmitted to the other AV device. Let
This is a data transmission method that does not transmit encrypted data and key information when it is determined that authentication is not performed based on the exchange of commands.

In the present invention, the data reproducing device reproduces the data, encrypts the reproduced data, and determines whether the other AV device is authenticated by the data reproducing device between the data reproducing device and the other AV device. exchanges of commands to, based on the exchange of the command, if it is determined that the user is authenticated, the data reproduction apparatus decrypts the encrypted data encrypted by the data reproducing apparatus, the encrypted data Since the command for turning on the switch circuit of the other AV device is transmitted to the other AV device together with the key information for the encryption, the command is encrypted only to a specific partner permitted to transfer. Control that allows data to be decoded is possible. For this reason, the data transferred to the bus can be reliably protected.

  According to the present invention, it is possible to control such that the other party is specified and data is transferred only to the specific other party, or only the specific other party is allowed to receive data. For this reason, for example, when a plurality of digital VTRs are connected to the bus, control can be performed so that data can be recorded only by a specific digital VTR that is permitted to record data, thereby ensuring data protection.

Embodiments of the present invention will be described with reference to the drawings in the following order.
a. Overall system b. First embodiment b1. Example of device for transferring data from device to bus side b2. Examples of devices that transfer data from the bus side to the device side b3. Examples of devices that transfer data in both directions b4. Examples of devices for recording / reproducing data b5. System example c. Second embodiment c1. Example of device transferring data from device to bus side c2. Examples of devices that transfer data from the bus side to the device side c3. Examples of devices that transfer data in both directions c4. Examples of devices for recording / reproducing data c5. System example

a. Overall System Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a video system to which the present invention can be applied. This video system is obtained by connecting a plurality of AV devices using a common bus.

  In FIG. 1, 1 is a digital decoder box, 2 and 3 are digital VTRs. The digital decoder box 1 decodes a digital satellite broadcast reception signal received by the parabolic antenna 6 and outputs an analog video signal. The video signal decoded by the digital decoder box 1 can be displayed on the television receiver 4 and can be transferred to other AV devices via the bus 5. The television receiver 4 receives a normal analog television broadcast. The digital VTRs 2 and 3 can record / reproduce digital video signals. These digital decoder box 1, digital VTR 2, and digital VTR 3 are connected to bus 5.

  Digital data is transferred to the bus 5 and commands for each device are transmitted. Data can be transferred between the devices via the bus 5. That is, the video signal from the digital decoder box 1 can be sent to the digital VTR 2 or 3 via the bus 5, and the video signal from the digital decoder box 1 can be recorded by the digital VTR 2 or 3. Further, a reproduction signal from the digital VTR 2 or 3 can be sent to the digital decoder box 1 via the bus 5, and this signal can be decoded by the digital decoder box 1 and displayed on the television receiver 4. Further, the reproduction signal of the digital VTR 2 can be sent to the digital VTR 3 via the bus 5 and dubbing can be performed between the digital VTR 2 and the digital VTR 3.

  In the above example, the television receiver 4 that receives normal television broadcast is used, and the digital decoder box 1 and the digital VTRs 2 and 3 are connected to the bus 5 so that the satellite broadcast reception signal can be projected. However, of course, other AV devices can be connected to form a system.

  That is, FIG. 2 shows another example of the video system. In this example, a television receiver 14 incorporating a digital video decoder is used. The digital satellite broadcast received by the parabolic antenna 16 is decoded by a decoder in the television receiver 14 and projected on the television receiver 14. In addition to the digital VTR 12, this video system is provided with a digital video disc player 19, an MPEG decoder 17, and an analog VTR 18. The digital video disc player 19 reproduces an optical disc on which a video signal compressed by MPEG, for example, is recorded. The analog VTR 18 records / reproduces an analog video signal. An MPEG decoder 17 is provided so that the analog VTR 18 can record a digital video signal transferred via the bus 15. A television receiver 14 with a built-in digital video decoder, a digital video disk 19, and an MPEG decoder 17 are connected to a bus 15. Data can be transferred between the devices via the bus 15.

b. First Embodiment As described above, the present invention is used to protect data transferred to a bus in a system in which a plurality of AV devices are connected to a common bus. In the first embodiment of the present invention, a device whose transfer is permitted is specified in advance by a command, data is delivered only to a device that is permitted to transfer, and data is transferred to a device that is not permitted to transfer. In order to prevent this, data is protected by providing a switch for each device. AV devices include devices that transfer data from the device in the direction of the bus, devices that import data from the bus to the device, and devices that transfer data in both directions. Furthermore, there are devices capable of recording / reproducing data. A device that transfers data from the device to the bus side is, for example, a digital video disc player. A device that captures data from the bus to the device side is, for example, an MPEG decoder or a television receiver with a built-in decoder. A device to which data is transferred bidirectionally is, for example, a digital decoder box. A device capable of recording / reproducing data is, for example, a digital VTR. The configuration of each device will be described below.

b1. Example of device that transfers data from device to bus side In a device that transfers data from a device to the bus side, a switch circuit that is turned on / off by a controller is provided on the digital data output side. . When data is transferred to each device via the bus, first, a command is exchanged with each device in advance, and it is determined whether transfer is permitted using the key information. Then, the switch circuit is turned on only for the devices that are permitted to transfer, and data is transferred. For devices that are not permitted to transfer data, the switch circuit is turned off and data transfer is rejected.

  FIG. 3 shows a digital video disc player as an example of such a device. In FIG. 3, for example, a video signal compressed by MPEG is optically recorded on the optical disc 21. The optical disk 21 is rotated by a spindle motor 22. The signal on the optical disk 21 is reproduced by the optical pickup 23, and this reproduction signal is supplied to the reproduction circuit 24. The reproduction circuit 24 performs processing such as data demodulation and error correction. The output of the reproduction circuit 24 is supplied to the switch circuit 25. The switch circuit 25 is on / off controlled by the controller 27. The output of the switch circuit 25 is supplied to the I / O port 26. In addition, commands are exchanged with other devices by the controller 27 via the I / O port 26. The controller 27 is given key information from the key generator 28.

  In such a digital video disc player, when reproducing data is transferred to another AV device via a bus, first, commands are exchanged using the key information via the bus. With this command, the device that is permitted to transfer is specified using the key information. Only when data is transferred to a device that is permitted to transfer, the switch circuit 25 is turned on, and the data from the reproduction circuit 24 is transferred via the bus. Otherwise, the switch circuit 25 is turned off. As a result, data can be transferred only to devices that are permitted to transfer, and data transfer to devices that are not permitted can be rejected.

b2. Examples of devices that transfer data from the bus side to the device side In devices that capture data from the bus side to the device side, a switch circuit that is controlled on / off by the controller is provided on the digital data input side. It is done. When data is received from each device via the bus, first, a command is exchanged with each device, and it is determined whether transfer is permitted using the key information. Then, the switch circuit is turned on only for devices that are permitted to transfer. For devices that are not permitted to transfer data, the switch circuit is turned off and data transfer is rejected.

  FIG. 4 shows an MPEG decoder as an example of such a device. In FIG. 4, data from the I / O port 31 is supplied to the switch circuit 32. The switch circuit 32 is on / off controlled by the controller 36. The output of the switch circuit 32 is supplied to the MPEG decoder 33. Video data is decoded by the MPEG decoder 33. The output of the MPEG decoder 33 is output from an output terminal 35 via a D / A converter 34. Commands are exchanged with other devices by the controller 36 via the I / O port 31. Key information is given to the controller 36 from the key generator 37.

  When data is transferred to the MPEG decoder 33 from another AV device via the bus, first, a command is exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. The switch circuit 32 is turned on only for data from a device that is permitted to transfer, and the switch circuit 32 is turned off otherwise. As a result, data can be received only from devices that are permitted to transfer data, and data from devices that are not permitted to transfer data can be rejected.

  FIG. 5 shows a television receiver with a built-in decoder as another example of such a device. In FIG. 5, a normal television broadcast reception signal is supplied to the input terminal 41. A signal from the input terminal 41 is supplied to the tuner circuit 43. A tuner circuit 43 extracts a signal of a desired reception channel. The output of the tuner circuit 43 is supplied to the terminal 45A of the switch circuit 45.

  The input terminal 42 is supplied with a compressed digital video signal from a satellite. A signal from the input terminal 42 is supplied to the digital tuner circuit 44. A desired reception channel is selected by the digital tuner circuit 44. The output of the digital tuner circuit 44 is supplied to the terminal 45B of the switch circuit 45.

  Data sent via the I / O port 46 is supplied to the switch circuit 47. On / off of the switch circuit 47 is controlled by the controller 48. The output of the switch circuit 47 is supplied to the terminal 45C of the switch circuit 45. In addition, commands are exchanged with other devices by the controller 48 via the I / O port 46. The controller 48 is provided with key information from the key generator 52.

  When receiving a normal television broadcast, the switch circuit 45 is set to the terminal 45A side. When receiving digital broadcasting from a satellite, the switch circuit 45 is set to the terminal 45B side. When the data sent via the I / O port 46 is displayed, the switch circuit 45 is set to the terminal 45C side.

  The output of the switch circuit 45 is supplied to the descrambler 49. The descrambler 49 is used to unscramble the received signal when it is scrambled. The output of the descrambler 49 is supplied to the MPEG decoder 50. The video signal is decoded by the MPEG decoder 50. In the case of receiving a normal video signal, the MPEG decoder 50 is passed. The output of the MPEG decoder 50 is supplied to the signal processing circuit 51. The output of the signal processing circuit 51 is supplied to the CRT display 53.

  In such a television receiver, when data is transferred from another AV device via the bus, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. Then, the switch circuit 47 is turned on only for data from a device that is permitted to transfer, and otherwise the switch circuit 47 is turned off. As a result, data can be received only from devices that are permitted to transfer, and data from devices that are not permitted to be transferred can be rejected.

b3. Examples of devices that transfer data in both directions In devices that transfer data in both directions, the digital data output side is provided with a switch circuit that is controlled on and off by the controller, and the digital data input side In addition, a switch circuit whose on / off is controlled by a controller is provided. When data is transferred to each device via a bus, first, commands are exchanged with each device in advance, and it is determined whether transfer is permitted using key information. Then, the switch circuit on the output side is turned on only for devices that are permitted to transfer, the switch circuit is turned off for devices that are not permitted to transfer, and data transfer is rejected. When data is received from each device via the bus, commands are exchanged with each device in advance, and it is determined whether or not transfer is permitted using the key information. The switch circuit on the input side is turned on only for devices that are permitted to transfer, and the switch circuit on the input side is turned off for devices that are not permitted to transfer, and data transfer is rejected.

  FIG. 6 shows a digital video box as an example of such a device. In FIG. 6, a compressed digital video signal from a satellite is supplied to an input terminal 61. A signal from the input terminal 61 is supplied to the digital tuner circuit 62. A desired reception channel is selected by the digital tuner circuit 62. The output of the digital tuner circuit 62 is supplied to the descrambler 63. The descrambler 63 is used to unscramble the received signal when it is scrambled. The output of the descrambler 63 is supplied to the switch circuit 64 and also supplied to the terminal 65A of the switch circuit 65. On / off of the switch circuit 64 is controlled by the controller 67. The output of the switch circuit 64 is supplied to the I / O port 66.

  Data sent via the I / O port 66 is supplied to the switch circuit 68. On / off of the switch circuit 68 is controlled by the controller 67. The output of the switch circuit 68 is supplied to the terminal 65B of the switch circuit 65. In addition, commands are exchanged with other devices by the controller 67 via the I / O port 66. The controller 67 is provided with key information from the key generation unit 69.

  The switch circuit 65 is switched between when the received signal is displayed on the television receiver and when the transmitted data is displayed on the television receiver. When the received signal is displayed on the television receiver, the switch circuit 65 is set to the terminal 65A side. When an image based on the data sent via the bus is displayed on the television receiver, the switch circuit 65 is set on the terminal 65B side.

  The output of the switch circuit 65 is supplied to the MPEG decoder 70. The video signal is decoded by the MPEG decoder 70. The output of the MPEG decoder 70 is supplied to the D / A converter 71. The output of the D / A converter 71 is output from the output terminal 72.

  This digital video box is used when a received signal is decoded and displayed on a television receiver. Further, this digital video box is used when receiving data is sent to another device via a bus, and also receives and decodes data from another device sent via the bus and decodes it to a television receiver. Used when supplying to

  When transferring data from the digital video box to another AV device via the bus, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. Data from the descrambler 63 is transferred via the bus. At this time, the switch circuit 64 is turned on only when data is transferred to a device that is permitted to transfer, and the switch circuit 64 is turned off otherwise. As a result, data can be transferred only to devices that are permitted to transfer, and data transfer to devices that are not permitted to transfer can be rejected.

  When the digital video box receives data from another AV device via the bus, the switch circuit 65 is set to the terminal 65B side. First, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. Then, the switch circuit 68 is turned on only for data from a device that is permitted to transfer, and otherwise the switch circuit 68 is turned off. As a result, data can be received only from devices that are permitted to transfer.

b4. Example of equipment for recording / reproducing data In an apparatus for recording / reproducing data, a switch circuit that is controlled to be turned on / off by a controller is provided on the output side of digital data, and on the input side of digital data A switch circuit that is controlled to be turned on / off by a controller is provided. Then, a card key is attached to specify whether or not the device is permitted to transfer.

  When transferring data to each device via the bus during playback, first exchange commands with each device in advance, use the key information to determine whether transfer is permitted, and transfer The switch circuit on the output side is turned on to send data only to devices that are permitted to transmit data, and the switch circuit is turned off to devices that are not permitted to transfer data so that data is not transferred. Also, when data is received from each device via the bus during recording, commands are exchanged with each device in advance, the key information is used to determine whether transfer is permitted, and transfer is permitted. The switch circuit on the input side is turned on only for the devices that are connected, and the switch circuit on the input side is turned off for devices that are not permitted to transfer, and data transfer is rejected.

  FIG. 7 shows a digital VTR as an example of such a device. In FIG. 7, when data transferred via the bus is recorded, the data transferred via the I / O port 81 is supplied to the switch circuit 82. The output of the switch circuit 82 is supplied to the recording / reproducing circuit 83. This data is recorded by the recording / reproducing circuit 83. During reproduction, the data reproduced from the recording / reproducing circuit 83 is supplied to the switch circuit 84. The output of the switch circuit 84 is supplied to the I / O port 81. Further, commands are exchanged with other devices via the I / O port 81. A card key 86 is detachably attached to the card attachment terminal 87. Key information is given from the card key 86 to the controller 85.

  When recording data from another AV device sent via the bus to the digital VTR, first, a command is exchanged using the key information of the card key 86 via the bus. This command identifies a device that is permitted to transfer. When the transfer is permitted, the switch circuit 82 is turned on, and otherwise, the switch circuit 82 is turned off. As a result, data can be recorded only when transfer is permitted.

  When the reproduction data from the digital VTR is transferred to another AV device via the bus, first, a command is exchanged using the key information of the card key 86 via the bus. This command identifies a device that is permitted to transfer. Then, the reproduction data from the recording / reproducing circuit 83 is transferred via the bus. At this time, the switch circuit 84 is turned on only when data is transferred to a device that is permitted to transfer, and the switch circuit 84 is turned off otherwise. As a result, it is possible to transfer the reproduction data only to devices that are permitted to transfer, and it is possible to refuse transfer of data to devices that are not permitted to transfer.

b5. System Example The following describes how data is protected by using each device configured as described above. FIG. 8 shows a system comprising the digital decoder box 101, the digital VTRs 102 and 103, and the television receiver 104 as shown in FIG. 1 using the AV equipment configured as described above. The digital decoder box 101 is configured as shown in FIG. 6, and the digital VTRs 102 and 103 are configured as shown in FIG. The digital decoder box 101 and the digital VTRs 102 and 103 are commonly connected to the bus 105.

  Commands and data are transferred on the bus 105. The command is transferred by designating a destination so that predetermined processing can be performed for each video device. Data is transmitted without specifying a destination.

  When data is transferred between AV devices, processing as shown in FIG. 9 is performed. That is, first, a command for determining whether or not transfer is permitted is transmitted (step S1). Upon receiving the command, each device processes the command according to the key information of each device (step S2), and returns data that has undergone predetermined processing as an acknowledge. It is determined whether an acknowledge has been received (step S3). When the acknowledge is received, the acknowledge, which is the data processed based on the key information for each device, is compared with the data processed based on the key information based on the device that issued the command (step S4). If the mutual key information is correct, the two match. If each other's key information is incorrect, they will not match. It is determined whether or not they match (step S5). If they match, the data is allowed to be transferred to the AV device (step S6). If they do not match, the data is transferred to the AV device. Is rejected (step S7).

  For example, as shown in FIG. 8, it is assumed that no card key is attached to the digital VTR 102 and a card key 86 B is attached only to the digital VTR 103. Assume that data is transferred between the digital decoder box 101 and the digital VTRs 102 and 103.

  When a recording command is sent from the digital decoder box 101 side to the digital VTRs 102 and 103 and data from the digital decoder box 101 is transferred to the digital VTRs 102 and 103 for recording, processing as shown in FIGS. 10A and 10B is performed. .

  As shown in FIG. 10A, a recording command is given to the digital VTR 102 from the digital decoder box 101 side. When the recording command is transferred to the digital VTR 102, the digital VTR 102 forms an acknowledge based on the key information, and returns this acknowledge to the digital decoder box 101. Since no digital key is attached to the digital VTR 102, the acknowledge returned from the digital VTR 102 to the digital decoder box 101 is not predetermined data. For this reason, data transfer is refused thereafter.

  As shown in FIG. 10B, a recording command is given to the digital VTR 103 from the digital decoder box 101 side. When the command is transferred to the digital VTR 103, the digital VTR 103 forms an acknowledge based on the key information and returns this acknowledge to the digital decoder box 101. Since the card key 86B is attached to the digital VTR 103, the acknowledge returned from the digital VTR 103 to the digital decoder box 101 is predetermined data. Therefore, data is transferred from the digital decoder box 101 to the digital VTR 103 thereafter.

  When a playback command is sent from the digital decoder box 101 side to the digital VTRs 102 and 103 and the playback data from the digital VTRs 102 and 103 are transferred to the digital decoder box 101, processing as shown in FIGS. 11A and 11B is performed.

  As shown in FIG. 11A, a playback command is given to the digital VTR 102 from the digital decoder box 101 side. When the reproduction command is transferred to the digital VTR 102, the digital VTR 102 forms an acknowledge based on the key information, and returns this acknowledge to the digital decoder box 101. Since no digital key is attached to the digital VTR 102, the acknowledge returned from the digital VTR 102 to the digital decoder box 101 is not predetermined data. For this reason, data transfer is refused thereafter.

  As shown in FIG. 11B, a reproduction command is given to the digital VTR 103 from the digital decoder box 101 side. When the playback command is transferred to the digital VTR 103, the digital VTR 103 forms an acknowledge based on the key information and returns this acknowledge to the digital decoder box 101. Since a card key is attached to the digital VTR 103, the acknowledge returned from the digital VTR 103 to the digital decoder box 101 is predetermined data. Therefore, the reproduction data from the digital VTR 103 is transferred to the digital decoder box 101 thereafter.

  When a data transmission command is sent from the digital VTRs 102 and 103 side to the digital decoder box 101 side and the data from the digital decoder box 101 is transferred to the digital VTRs 102 and 103 and recorded, the processing shown in FIGS. 12A and 12B is performed. Is called.

  As shown in FIG. 12A, a data transmission command is given from the digital VTR 102 side to the digital decoder box 101 side. When the data transmission command is transferred to the digital decoder box 101, the digital decoder box 101 forms an acknowledge based on the key information and returns it to the digital VTR 102. Since no digital key is attached to the digital VTR 102, the acknowledge returned from the digital VTR 102 to the digital decoder box 101 does not match the predetermined data on the digital VTR 102 side. Therefore, thereafter, the digital VTR 102 refuses to take in data.

  As shown in FIG. 12B, a data transmission command is given from the digital VTR 103 side to the digital decoder box 101 side. When the data transmission command is transferred to the digital decoder box 101, the digital decoder box 101 forms an acknowledge based on the key information and returns it to the digital VTR 103. Since the card key 86B is attached to the digital VTR 103, the acknowledge returned from the digital VTR 103 to the digital decoder box 101 matches the predetermined data on the digital VTR 103 side. Therefore, data from the digital decoder box 101 is transmitted to the digital VTR 102 and this data is recorded by the digital VTR 103.

  When a data reception command is sent from the digital VTRs 102 and 103 to the digital decoder box 101 and the data from the digital VTRs 102 and 103 is transferred to the digital decode box 101, processing as shown in FIGS. 13A and 13B is performed.

  As shown in FIG. 13A, a data reception command is given from the digital VTR 102 side to the digital decoder box 101 side. When the data reception command is transferred to the digital decoder box 101, the digital decoder box 101 forms an acknowledge based on the key information and returns it to the digital VTR 102. Since no digital key is attached to the digital VTR 102, the acknowledge returned from the digital VTR 102 to the digital decoder box 101 does not match the predetermined data on the digital VTR 102 side. For this reason, data transfer from the digital VTR 103 is refused thereafter.

  As shown in FIG. 13B, a data reception command is given from the digital VTR 103 side to the digital decoder box 101 side. When a data reception command is transferred to the digital decoder box 101, the digital decoder box 101 forms an acknowledge based on the key information and returns it to the digital VTR 103. Since the card key 86B is attached to the digital VTR 103, the acknowledge returned from the digital VTR 103 to the digital decoder box 101 matches the predetermined data on the digital VTR 103 side. Therefore, data from the digital VTR 103 is transferred to the digital decoder box 101 and received by the digital decoder box 101 thereafter.

  As described above, in the first embodiment of the present invention, prior to data transfer between devices, commands are exchanged based on key information to determine whether transfer is permitted. Data is transferred only to devices that are permitted to transfer. Thereby, data can be protected.

c. Second Embodiment In the second embodiment of the present invention, a device that is permitted to transfer is specified in advance by a command, data is delivered only to the device that is permitted to transfer, and transfer is not permitted. Each device is provided with a switch so that the data is not transferred to the device, and the data is encrypted and transmitted to further strengthen the protection of the data.

c1. Example of device that transfers data from device to bus side In a device that transfers data from a device to the bus side, a switch circuit that is turned on / off by a controller is provided on the digital data output side. In addition, an encryption circuit is provided. When data is transferred to each device via the bus, first, a command is exchanged with each device in advance to determine whether transfer is permitted. Then, a key for decrypting the cipher is passed to the device that is permitted to transfer. For devices that are permitted to transfer, the switch circuit is turned on, and the data is encrypted and sent. Since a key is passed in advance to a device that is permitted to transfer data, the encrypted data can be decrypted. For devices that are not permitted to transfer data, the switch circuit is turned off and data transfer is rejected.

  FIG. 14 shows a digital video disc player as an example of such a device. In FIG. 14, for example, a video signal compressed by MPEG is optically recorded on an optical disk 121. This optical disk 121 is rotated by a spindle motor 122. The signal of the optical disk 121 is reproduced by the optical pickup 123, and this reproduction signal is supplied to the reproduction circuit 124. The reproduction circuit 124 performs processing such as data demodulation and error correction. The output of the reproduction circuit 124 is supplied to the switch circuit 125. The switch circuit 125 is on / off controlled by the controller 127. The output of the switch circuit 125 is supplied to the encryption circuit 129. In the encryption circuit 129, data to be transferred is encrypted. The output of the encryption circuit 129 is supplied to the I / O port 126. A command is transferred to the controller 127 via the I / O port 126. The controller 127 receives key information from the key generation unit 128.

  In such a digital video disc player, when reproducing data is transferred to another AV device via a bus, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. When data is transferred to a device that is permitted to transfer, a key for decryption is passed. Then, the switch circuit 125 is turned on. Therefore, the data from the reproduction circuit 124 is encrypted by the encryption circuit 129 and transferred via the bus. Otherwise, the switch circuit 125 is turned off. As a result, data can be transferred only to devices that are permitted to transfer, and data transfer to devices that are not permitted can be rejected. At the same time, since the data transferred to the bus is encrypted, the data transferred to the bus can be protected.

c2. Examples of devices that transfer data from the bus side to the device side In devices that capture data from the bus side to the device side, a switch circuit that is controlled on / off by the controller is provided on the digital data input side. And a decryption circuit is provided. When receiving data from each device via the bus, first, a command is exchanged with each device to determine whether transfer is permitted. If transfer is permitted, a key for decryption is received. For devices that are permitted to transfer, the switch circuit is turned on and data is input. This data is encrypted, but since the key for decryption is sent in advance, the encryption can be decrypted. For devices that are not permitted to transfer data, the switch circuit is turned off and data transfer is rejected.

  FIG. 15 shows an MPEG decoder as an example of such a device. In FIG. 15, data from the I / O port 131 is supplied to the switch circuit 132. The switch circuit 132 is on / off controlled by the controller 136. The output of the switch circuit 132 is supplied to the decryption circuit 138. The output of the decryption circuit 138 is supplied to the MPEG decoder 133. Video data is decoded by the MPEG decoder 133. The output of the MPEG decoder 133 is output from the output terminal 135 via the D / A converter 134. Commands are exchanged by the controller 136 via the I / O port 131. Key information is given to the controller 136 from the key generation unit 137.

  When data is transferred from the other AV equipment to the MPEG decoder 133 via the bus, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. If the transfer is permitted, a key for decryption is received, and the key for decryption is set in the decryption circuit 138. Then, the switch circuit 132 is turned on. Thereby, the data sent via the bus is input. This data is encrypted, but since the key is sent in advance, the encryption can be decrypted. If the data transfer is not permitted, the switch circuit 132 is turned off and the data transfer is rejected.

  FIG. 16 shows an example of a television receiver with a built-in decoder. In FIG. 16, an input terminal 141 is supplied with a normal television broadcast reception signal. A signal from the input terminal 141 is supplied to the tuner circuit 143. A tuner circuit 143 extracts a signal of a desired reception channel. The output of the tuner circuit 143 is supplied to the terminal 145A of the switch circuit 145.

  The input terminal 142 is supplied with a compressed digital video signal from a satellite. A signal from the input terminal 142 is supplied to the digital tuner circuit 144. A desired reception channel is selected by the digital tuner circuit 144. The output of the digital tuner circuit 144 is supplied to the terminal 145B of the switch circuit 145.

  Data sent via the I / O port 146 is supplied to the switch circuit 147. On / off of the switch circuit 147 is controlled by the controller 148. The output of the switch circuit 147 is supplied to the decryption circuit 154. The decryption circuit 154 is given key information for decryption from the controller 148. The output of the decryption circuit 154 is supplied to the terminal 145C of the switch circuit 145. Further, the command is transferred to the controller 148 via the I / O port 146. The controller 148 is given key information from the key generator 152.

  When receiving a normal television broadcast, the switch circuit 145 is set to the terminal 145A side. In the case of receiving digital broadcasting from a satellite, the switch circuit 145 is set on the terminal 145B side. When reproducing data sent via the I / O port 146, the switch circuit 145 is set to the terminal 145C side.

  The output of the switch circuit 145 is supplied to the descrambler 149. The descrambler 149 is used to unscramble the received signal when it is scrambled. The output of the descrambler 149 is supplied to the MPEG decoder 150. The video signal is decoded by the MPEG decoder 150. Note that when receiving a normal video signal, the MPEG decoder 150 is passed. The output of the MPEG decoder 150 is supplied to the signal processing circuit 151. The output of the signal processing circuit 151 is supplied to the CRT display 153.

  In such a television receiver, when data is transferred from another AV device via the bus, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. If data transfer is permitted, a key for decryption is received. In the case of a device that is permitted to transfer, the switch circuit 147 is turned on and data is sent. This data is encrypted, but since the key is sent in advance, the encryption can be decrypted. When the data transfer is not permitted, the switch circuit 147 is turned off and the data transfer is rejected.

c3. Examples of devices that transfer data bi-directionally In devices that transfer data bi-directionally, a switch circuit that is turned on / off by a controller is provided on the digital data output side, and the data is encrypted Is provided. Further, on the digital data input side, a switch circuit whose on / off is controlled by a controller is provided, and a decryption circuit is provided.

  When data is transferred to each device via the bus, first, a command is exchanged with each device in advance, and it is determined whether transfer is permitted using the key information. If transfer is permitted, a key for decryption is passed. Then, the encrypted data is sent. If transfer is not permitted, data transfer is rejected.

  When data is received from each device via the bus, commands are exchanged with each device in advance, and it is determined whether transfer is permitted using the key information. A key for decryption is sent from a device that is permitted to transfer data. Then, the switch circuit on the input side is turned on, and the data is encrypted and sent. Although this data is encrypted, since the key information is sent in advance, the encryption can be decrypted. Data transfer is rejected for devices that are not permitted to transfer.

  FIG. 17 shows a digital video box as an example of such a device. In FIG. 17, a compressed digital video signal from a satellite is supplied to an input terminal 161. A signal from the input terminal 161 is supplied to the digital tuner circuit 162. A desired reception channel is selected by the digital tuner circuit 162. The output of the digital tuner circuit 162 is supplied to the descrambler 163. The descrambler 163 is used to unscramble the received signal when it is scrambled. The output of the descrambler 163 is supplied to the encryption circuit 173. The output of the encryption circuit 173 is supplied to the switch circuit 164 and also supplied to the terminal 165A of the switch circuit 165. The switch circuit 164 is turned on / off by the controller 167. The output of the switch circuit 164 is supplied to the I / O port 166.

  Data sent via the I / O port 166 is supplied to the switch circuit 168. The switch circuit 168 is controlled to be turned on / off by the controller 167. The output of the switch circuit 168 is supplied to the decryption circuit 174. The output of the decryption circuit 174 is supplied to the terminal 165B of the switch circuit 165. Further, the command is transferred to the controller 167 via the I / O port 166. The controller 167 is given key information from the key generator 169.

  The switch circuit 165 can be switched between when the received signal is displayed on the television receiver and when the transmitted data is displayed on the television receiver. When the received signal is displayed on the television receiver, the switch circuit 165 is set to the terminal 165A side. When an image based on the data sent via the bus is displayed on the television receiver, the switch circuit 165 is set on the terminal 165B side.

  The output of the switch circuit 165 is supplied to the MPEG decoder 170. The video signal is decoded by the MPEG decoder 170. The output of the MPEG decoder 170 is supplied to the D / A converter 171. The output of the D / A converter 171 is output from the output terminal 172. The output of the output terminal 172 is supplied to the video input terminal of the television receiver.

  This digital video box is used when a received signal is decoded and displayed on a television receiver. Further, this digital video box is used when receiving data is sent to another device via a bus, and also receives and decodes data from another device sent via the bus and decodes it to a television receiver. Used when supplying to

  When transferring data from the digital video box to another AV device via the bus, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. A key for decryption is passed to a device that is permitted to transfer data. Then, the switch circuit 164 is turned on, and the data from the descrambler 163 is encrypted by the encryption circuit 173 and transferred via the bus. When transfer is not permitted, the switch circuit 164 is turned off. Thereby, it is possible to refuse transfer of data of a device that is not permitted to transfer.

  When the digital video box receives data from another AV device via the bus, the switch circuit 165 is set to the terminal 165B side. Then, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. A key for decryption is received for data from a device that is permitted to transfer. When the transfer is permitted, the switch circuit 168 is turned on and data is input. Although this data is encrypted, a key for decryption is sent so that the cipher can be decrypted. If the transfer is not permitted, the switch circuit 168 is turned off. Thereby, transfer of data from a device that is not permitted to transfer can be rejected.

c4. Example of equipment for recording / reproducing data In an apparatus for recording / reproducing data, a switch circuit that is controlled to be turned on / off by a controller is provided on the output side of digital data, and on the input side of digital data A switch circuit that is controlled to be turned on / off by a controller is provided. Then, a card key is attached to specify whether or not the device is permitted to transfer.

  When data is transferred to each device via the bus during playback, first, a command is exchanged with each device in advance, and it is determined whether transfer is permitted. If transfer is permitted, a key for decryption is passed. Then, the output side switch circuit is turned on, and the data is encrypted and sent. In a device where transfer is not permitted, the output-side switch circuit is turned off, and data transfer is rejected. When data is received from each device via the bus during recording, a command is exchanged with each device in advance to determine whether transfer is permitted. If transfer is permitted, a key for decryption is sent. When the transfer is permitted, the switch circuit on the input side is turned on, and data is input after being encrypted. This data is encrypted, but since the key for decryption has been sent in advance, the cipher can be decrypted. For devices that are not permitted to transfer data, the input-side switch circuit is turned off and data transfer is rejected.

  FIG. 18 shows a digital VTR as an example of such a device. In FIG. 18, when recording data transferred via the bus, the data transferred via the I / O port 181 is supplied to the switch circuit 182. The output of the switch circuit 182 is supplied to the decryption circuit 188. The decryption circuit 188 is given a key for decryption from the controller 185. The output of the decryption circuit 188 is supplied to the recording / reproducing circuit 183. This data is recorded by the recording / reproducing circuit 183. During reproduction, the data reproduced from the recording / reproducing circuit 183 is supplied to the encryption circuit 189. The output of the encryption circuit 189 is supplied to the switch circuit 184. The output of the switch circuit 184 is supplied to the I / O port 181. In addition, the command is transferred to the controller 185 via the I / O port 181. A card key 186 is detachably attached to the card attachment terminal 187. Key information is given from the card key 186 to the controller 185.

  When recording data from another AV device sent via the bus to the digital VTR, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. If transfer is permitted, a key for decryption is sent. When the transfer is permitted, the switch circuit 182 is turned on and data is input. This data is encrypted, but if transfer is permitted, a key for decrypting the encryption is sent, so that the cipher can be decrypted. If transfer is not permitted, the switch circuit 182 is turned off. Thereby, data can be recorded only when transfer is permitted, and data can be rejected when transfer is not permitted.

  When the reproduction data from the digital VTR is transferred to another AV device via the bus, first, commands are exchanged via the bus. With this command, the device that is permitted to transfer is specified using the key information. A key for decryption is passed to a device that is permitted to transfer data. Then, the switch circuit 184 is turned on, and the reproduction data from the recording / reproducing circuit 183 is encrypted and transferred via the bus. When the transfer is not permitted, the switch circuit 184 is turned off. As a result, data transfer can be rejected to a device that is not permitted to transfer data.

c5. System Example The following describes how data is protected by using each device configured as described above. FIG. 19 shows a system comprising the digital decoder box 201, the digital VTRs 202 and 203, and the television receiver 204 as shown in FIG. 1 using the AV equipment configured as described above. The digital decoder box 201 is configured as shown in FIG. 17, and the digital VTRs 202 and 203 are configured as shown in FIG. The digital decoder box 201 and the digital VTRs 202 and 203 are commonly connected to the bus 205.

  Commands and data are transferred on the bus 205. The command is transferred by designating a destination so that predetermined processing can be performed for each video device. Data is transmitted without specifying a destination.

  When data is transferred between AV devices, processing as shown in FIG. 20 is performed. That is, first, a command for determining whether or not transfer is permitted is transmitted (step S21). Upon receiving the command, each device processes the command according to the key information of each device (step S22), and returns the data that has undergone the predetermined processing as an acknowledge. It is determined whether or not an acknowledge has been received (step S23). When the acknowledge is received, the acknowledge, which is the data processed based on the key information for each device, is compared with the data processed based on the key information based on the device that issued the command (step S24). If the mutual key information is correct, the two match. If each other's key information is incorrect, they will not match. It is determined whether or not they match (step S25). If they match, transmission / reception of encrypted data to be transferred to the AV device is permitted (step S26). Transfer of data to the device is rejected (step S27).

  For example, in FIG. 19, it is assumed that no card key is attached to the digital VTR 202 and a card key 186B is attached only to the digital VTR 203. Assume that data is transferred between the digital decoder box 201 and the digital VTRs 202 and 203.

  When a recording command is sent from the digital decoder box 201 side to the digital VTRs 202 and 203 side, and data from the digital decoder box 201 is transferred to the digital VTRs 202 and 203 for recording, processing as shown in FIGS. 21A and 21B is performed. .

  As shown in FIG. 21A, a recording command is given to the digital VTR 202 from the digital decoder box 201 side. When the recording command is transferred to the digital VTR 202, the digital VTR 202 forms an acknowledge based on the key information, and returns this acknowledge to the digital decoder box 201. Since no digital key is attached to the digital VTR 202, the acknowledge returned from the digital VTR 202 to the digital decoder box 201 is not predetermined data. For this reason, data transfer is refused thereafter.

  As shown in FIG. 21B, a recording command is given to the digital VTR 203 from the digital decoder box 201 side. When the command is transferred to the digital VTR 203, the digital VTR 203 forms an acknowledge based on the key information, and returns this acknowledge to the digital decoder box 201. Since the card key 186B is attached to the digital VTR 203, the acknowledge returned from the digital VTR 203 to the digital decoder box 201 is predetermined data. Thus, it can be seen that the digital decoder box 201 is a device to which the digital VTR 203 is permitted to transfer. When the digital decoder box 201 determines that the digital VTR 203 is a device that is permitted to transfer, the digital decoder box 201 sends a key for decryption to the digital VTR 203. The digital decoder box 201 encrypts the data and transmits it. The encrypted data sent from the digital decoder box 201 is supplied to the digital VTR 203. This data is encrypted, but since the key for decryption has already been sent to the digital VTR 203, the encryption can be decrypted. The encryption of the data sent by the decryption circuit 189B of the digital VTR 203 is decrypted, and this data is recorded by the digital VTR 203.

  When a reproduction command is sent from the digital decoder box 201 side to the digital VTRs 202 and 203 side and reproduction data from the digital VTRs 202 and 203 is transferred to the digital decoder box 201, processing as shown in FIGS. 22A and 22B is performed.

  As shown in FIG. 22A, a playback command is given to the digital VTR 202 from the digital decoder box 201 side. When the playback command is transferred to the digital VTR 202, the digital VTR 202 forms an acknowledge based on the key information, and returns this acknowledge to the digital decoder box 201. Since no digital key is attached to the digital VTR 202, the acknowledge returned from the digital VTR 202 to the digital decoder box 201 is not predetermined data. For this reason, data transfer is refused thereafter.

  As shown in FIG. 22B, a reproduction command is given to the digital VTR 203 from the digital decoder box 201 side. When the playback command is transferred to the digital VTR 203, the digital VTR 203 forms an acknowledge based on the key information, and returns this acknowledge to the digital decoder box 201. Since the card key is attached to the digital VTR 203, the acknowledge returned from the digital VTR 203 to the digital decoder box 201 is predetermined data. Thereby, it can be seen that the digital VTR 203 is a device to which the digital decoder box 201 is permitted to transfer. When the digital VTR 203 finds that the digital decoder box 201 is a device that is permitted to transfer, it passes a key for decryption to the digital decoder box 201. Then, the reproduction data from the digital VTR 203 is encrypted and transferred to the digital decoder box 201. Although this data has been encrypted, since a key for decryption has already been sent, the digital decoder box 201 can decrypt the cipher.

  When a data transmission command is sent from the digital VTRs 202 and 203 to the digital decoder box 201 and the data from the digital decoder box 201 is transferred to the digital VTRs 202 and 203 for recording, the processing shown in FIGS. 23A and 23B is performed. Is called.

  As shown in FIG. 23A, a data transmission command is given from the digital VTR 202 side to the digital decoder box 201 side. When the data transmission command is transferred to the digital decoder box 201, the digital decoder box 201 forms an acknowledge based on the key information and returns it to the digital VTR 202. Since no digital key is attached to the digital VTR 202, the acknowledge returned from the digital VTR 202 to the digital decoder box 201 does not match the predetermined data on the digital VTR 202 side. For this reason, data transfer to the digital VTR 202 is refused thereafter.

  As shown in FIG. 23B, a data transmission command is given from the digital VTR 203 side to the digital decoder box 201 side. When the data transmission command is transferred to the digital decoder box 201, the digital decoder box 201 forms an acknowledge based on the key information and returns it to the digital VTR 203. Since the card key 186B is attached to the digital VTR 203, the acknowledge returned from the digital VTR 203 to the digital decoder box 201 matches the predetermined data on the digital VTR 203 side. As a result, it can be seen that the digital decoder box 201 is a device for which the digital VTR 203 is permitted. When it is found that the digital decoder box 201 is a device for which the digital VTR 203 is permitted, the digital decoder box 201 passes a key for decryption to the digital VTR 203. Then, encrypted data is transmitted from the digital decoder box 201. This data is encrypted, but key information for decryption is sent to the digital VTR 203. Therefore, the digital VTR 203 can decrypt this encrypted data. This data is decoded and recorded by the digital VTR 203.

  When a data reception command is sent from the digital VTRs 202 and 203 to the digital decoder box 201 and the data from the digital VTRs 202 and 203 is transferred to the digital decode box 201, processing as shown in FIGS. 24A and 24B is performed.

  As shown in FIG. 24A, a data reception command is given from the digital VTR 202 side to the digital decoder box 201 side. When the data reception command is transferred to the digital decoder box 201, the digital decoder box 201 forms an acknowledge based on the key information and returns it to the digital VTR 202. Since no digital key is attached to the digital VTR 202, the acknowledge returned from the digital VTR 202 to the digital decoder box 201 does not match the predetermined data on the digital VTR 202 side. For this reason, thereafter, transfer of data from the digital VTR 203 is rejected.

As shown in FIG. 24B, a data reception command is given from the digital VTR 203 side to the digital decoder box 201 side. When the data reception command is transferred to the digital decoder box 201, the digital decoder box 201 forms an acknowledge based on the key information and returns it to the digital VTR 203. Since the card key 186B is attached to the digital VTR 203 , the acknowledge returned from the digital decoder box 201 to the digital VTR 203 matches the predetermined data on the digital VTR 203 side. Thereby, it can be seen that the digital VTR 203 is a device to which the digital decoder box 201 is permitted to transfer. When the digital VTR 203 determines that the digital decoder box 201 is a device that is permitted to transfer, the digital VTR 203 sends a key for decryption to the digital decoder box 201. Then, the encrypted data is transmitted from the digital VTR 203. This data is encrypted, but a key for decryption is sent to the digital decoder box 201. Therefore, the encrypted data from the digital VTR 203 is transferred to the digital decoder box 201 and decrypted by the digital decoder box 201.

  Thus, in the second embodiment of the present invention, prior to transferring data between devices, commands are exchanged based on key information to determine whether transfer is permitted. Then, a key for decryption is sent to a device that is permitted to transfer data, and then the data is encrypted and transferred. In this way, data transmitted via the bus is encrypted, so that data can be further protected.

[BRIEF DESCRIPTION OF THE DRAWINGS] It is a perspective view used for description of an example of the video system which can apply this invention. It is a perspective view used for description of the other example of the video system which can apply this invention. It is a block diagram used for description of 1st Embodiment of this invention. It is a block diagram used for description of 1st Embodiment of this invention. It is a block diagram used for description of 1st Embodiment of this invention. It is a block diagram used for description of 1st Embodiment of this invention. It is a block diagram used for description of 1st Embodiment of this invention. It is a block diagram used for description of 1st Embodiment of this invention. It is a flowchart used for description of 1st Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 1st Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 1st Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 1st Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 1st Embodiment of this invention. It is a block diagram used for description of 2nd Embodiment of this invention. It is a block diagram used for description of 2nd Embodiment of this invention. It is a block diagram used for description of 2nd Embodiment of this invention. It is a block diagram used for description of 2nd Embodiment of this invention. It is a block diagram used for description of 2nd Embodiment of this invention. It is a block diagram used for description of 2nd Embodiment of this invention. It is a flowchart used for description of 2nd Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 2nd Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 2nd Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 1st Embodiment of this invention. It is a sequence chart which shows the transfer procedure of 2nd Embodiment of this invention.

Explanation of symbols

1, 101, 201 Digital decoder box 2, 3, 102, 103, 202, 203 Digital VTR
5, 105, 205 bus

Claims (4)

A data reproduction device as an AV device that reproduces data recorded on a recording medium and transmits the reproduced data to another AV device via a bus,
Reproducing means for reproducing data recorded on the recording medium;
Encryption means for encrypting data reproduced by the reproduction means;
Authentication means for exchanging commands with the other AV device for determining whether the other AV device is authenticated by the data reproducing device;
When it is determined that the other AV device is authenticated based on the exchange of the command, the data encrypted by the encryption unit with respect to the other AV device, and the encryption unit Transmission means for transmitting key information for decrypting the data encrypted by, and a command for turning on or off the switch circuit of the other AV device ;
Have
The command exchange for determining whether or not the authentication is performed is as follows.
Command information is transmitted from the data reproduction device to the other AV device,
The other AV device transmits the authentication information formed based on the key information of the other AV device based on the command information to the data reproduction device,
In the data reproduction device, the authentication information is compared with predetermined information formed based on key information of the data reproduction device, and if the authentication information matches the predetermined information, the other AV Performed by determining that the device is authenticated by the data reproduction device ;
By causing the other AV device that has been determined to be authenticated to turn on the switch circuit of the other AV device to receive the command for turning on the switch circuit of the other AV device, Allow the other AV device determined to be authenticated to receive the data encrypted by the encryption means and key information for decrypting the data encrypted by the encryption means <br / > Data playback device. 2. The data reproducing apparatus according to claim 1, wherein the key information of the data reproducing apparatus is recorded on a key information recording medium that can be attached to and detached from the data storage apparatus. A data transmission method in which a data reproduction device reproduces data recorded on a recording medium and transmits the reproduced data to another AV device via a bus,
The data reproducing device is
Reproducing the data recorded on the recording medium,
Encrypt the replayed data,
An exchange of a command for determining whether or not the other AV device is authenticated by the data reproducing device that reproduces data is performed between the data reproducing device and the other AV device. Command information to the other AV device, and the other AV device transmits authentication information formed based on the key information of the other AV device based on the command information to the data reproducing device, In the data reproduction device, the authentication information is compared with predetermined information formed based on key information of the data reproduction device, and if the authentication information matches the predetermined information, the other AV By determining that the device is authenticated by the data playback device;
When it is determined that the other AV device is authenticated by the data reproduction device based on the exchange of the command, the switch circuit of the other AV device is turned on for the other AV device. transmitting a command to the transmission of the switching circuit of the other AV devices that are determined to be authenticated is turned on, and the encrypted data and the key information for decrypting the encrypted data And let the other AV device receive
A data transmission method that does not transmit encrypted data and the key information when it is determined that authentication is not performed based on the exchange of commands. 4. The data transmission method according to claim 3, wherein the key information possessed by the data reproducing device is obtained from a key information recording medium detachably attached to the data storage device.

Images