JP2005051514A - Information transmission system and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a viewer unable to watch a program, if the viewer does not watch a CM (commercial message). <P>SOLUTION: A coding device 20 compresses and codes a program from a program bank 12, and a coding device 22 compression-codes a CM from a CM bank 14. An encryption device 32 encrypts a scramble key Ks by a work key Kw, and an encryption device 34 encrypts the encrypted scramble key Ks by a master key Km. An image scramble device 38 scrambles the output of the coding device 20 by the scramble key Ks. A multiplexer 40 multiplexes the outputs of the devices 32, 34 on the output of the device 38, and its output is applied to a synthesizer 50 via a buffer memory 44. A watermark forming device 36 creates watermark data from the outputs of the devices 32, 34, and an insertion apparatus 46 inserts the watermark into the output of the coding device 22. The output of the insertion apparatus 46 is applied to the synthesizer 50 via a buffer memory 48. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information transmission system and method, and more specifically, for example, an information transmission system applicable to a broadcast system that transmits an encrypted digital broadcast signal and its decryption key to an unspecified number of viewers. Regarding the method.

  Conventionally, in the case of broadcasting in which broadcast signal includes provision information (such as commercials) from a program sponsor, the provision information (when the viewer changes the reception channel during recording of provision information or records on a recording / playback device such as a VTR) The provided information may be skipped during playback while recording on a recording / playback apparatus such as a VTR while cutting commercials or the like. In these cases, the provided information from the program provider is not transmitted to the viewer.

  Due to the recording on the recording / reproducing apparatus, a problem in copyright law occurs. In digital broadcasting, since the image quality basically does not deteriorate, this problem becomes more prominent.

  FIG. 4 shows a schematic block diagram of a conventional digital broadcast signal transmission system. In the transmission device 110, the switching device 116 selects the program information 112 or the CM information 114 according to a predetermined time table and writes it in the storage device 118. That is, the switching device 116 multiplexes program information and CM information on the time axis. The encoder 120 sequentially reads the storage information in the storage device 118 and compresses and encodes the information using the MPEG method.

  The video scrambler 122 encrypts the output of the encoder 120, that is, the MPEG encoded video data according to the scramble key Ks. The encryption device 124 encrypts the scramble key Ks with the work key Kw, and applies the encrypted scramble key Ks to the multiplexing device 128 as common information. Another encryption device 126 encrypts the work key Kw with the master key Km assigned to each receiving device (set top box), and applies the encrypted work key to the multiplexing device 128 as individual information.

  The multiplexing device 128 includes scrambled video information from the video scramble device, common information from the encryption device 124 (encrypted scramble key Ks), and individual information from the encryption circuit 126 (encrypted work). Key) is multiplexed and output to the transmission line 130.

  The reception device 140 receives information output from the transmission device 110 to the transmission path 130. The separation device 142 separates the video information, common information, and individual information, and applies the individual information to the decryption device 144, the common information to the decryption device 146, and the video information to the video descramble device 148. The decryptor 144 decrypts the individual information using the master key Km held therein, and applies the decrypted work key Kw to the decryptor 146. The decryptor 146 decrypts the common information using the work key Kw decrypted by the decryptor 144, and applies the decrypted scramble key Ks to the video descrambler 148. The video descrambler 148 descrambles the video information from the separator 142 using the scramble key Ks from the decryptor 146, and outputs the MPEG encoded video information. The decoding device 150 decodes the MPEG encoded video information from the descrambling device 148 and outputs a standard format video signal.

  In the conventional system, when a program such as a movie is added with CM information to an unspecified number of viewers, it is unclear whether or not the intended CM information is reliably reproduced. For example, it may be duplicated by a duplicating apparatus, and CM information may be cut during that time.

  An object of the present invention is to provide an information transmission system and method for solving such inconvenience and ensuring reproduction of information provided by a program provider.

  The information transmission system according to the present invention includes a transmitting apparatus that transmits second information encrypted with the key information after the first information in which the key information is embedded, and the key information from the first information. A receiving device that extracts and decrypts the encrypted second information with the key information.

  The information transmission method according to the present invention generates first information in which key information is embedded, encrypts the second information with the key information, and after the first information in which the key information is embedded, Transmitting the second information encrypted with the information, extracting the key information from the received first information, and decrypting the received second information encrypted with the extracted key information It is characterized by.

  According to the present invention, the program viewer cannot obtain the scramble key Ks for decrypting the next section unless the provided information (CM) is reproduced. Further, even when this stream is dubbed to another recording medium, it is necessary to reproduce the provided information (CM) at the time of reproduction, so that the purpose of showing the CM of the program provider can be reliably achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of an embodiment of the present invention. The transmission device 10 reads a desired program from the program bank 12 and reads a desired CM from the CM bank 14. The encoding device 20 compresses and encodes the program read from the program bank 12, and the encoding device 22 compresses and encodes the CM read from the CM bank 14. The control device 24 controls the encoding devices 20 and 22 and blocks described later in the transmission device 10.

  The key generator 26 generates a scramble key Ks that is arbitrarily or randomly changed at predetermined time intervals. The key generation device 28 generates a work key Kw, and the key generation device 30 generates a master key Km that identifies the recipient. The encryption device 32 encrypts the scramble key Ks from the key generation device 26 with the work key Kw from the key generation device 28, and uses the encrypted scramble key Ks as common information for the encryption device 34 and the digital watermark creation device 36. And applied to the multiplexer 40 via the switching circuit 42. The encryption device 34 encrypts the encrypted scramble key Ks with the master key Km from the key generation device 30 and applies it to the digital watermark creation device 36 and the multiplexing device 40 as individual information.

  When a program is provided to an unspecified number of receiving terminals, the work key Kw is not encrypted with the master key Km, or separate from the individual master keys given in advance to the receiving terminals. The work key Kw is encrypted using the master key.

  The video scrambler 38 scrambles the compressed program data from the encoder 20 with the scramble key Ks from the key generator 26 and applies it to the multiplexer 40. The multiplexing device 40 multiplexes the common information with the output of the video scrambler 38 and further multiplexes the individual information at a predetermined timing. Information multiplexed by the multiplexing device 40 is applied to the synthesis device 50 via the buffer memory 44.

  In the case of normal receiver-limited transmission for limiting receivers, the multiplexing device 40 multiplexes common information and individual information into scrambled compressed program data. When the recipient is not limited, the video scrambler 38 does not scramble the compressed program data.

  The digital watermark creation device 36 uses the common information (encrypted scramble key Ks) from the encryption device 32 and the individual information (encrypted work or key) from the encryption device 34 to superimpose on the CM information. Create watermark data. The digital watermark insertion device 46 inserts or superimposes the digital watermark created by the digital watermark creation device 36 on the output (encoded CM information) of the coding device 22. The compressed CM information into which the digital watermark has been inserted by the digital watermark insertion device 46 is applied to the synthesis device 50 via the buffer memory 48.

  The synthesizer 50 synthesizes, that is, time-division multiplexes and outputs both pieces of information so that the information from the buffer memory 46 is arranged before the information from the buffer memory 44.

  FIG. 2 shows how the program data and provision information (CM data) transmitted from this embodiment change in time series. Provided information is inserted at an appropriate interval between program information. The program information is scrambled, but the provided information is transmitted in plain text without being scrambled. In the provided information, common information and individual information for decrypting the subsequent encrypted program data are inserted as digital watermark information. Therefore, in order to view the program data, it is necessary to reproduce the last provided information.

  FIG. 3 shows a schematic block diagram of the receiving apparatus. Stream data including the output data of the synthesizing device 50 in FIG. 1 is input to the separating device 62 of the receiving device 60. The separation device 62 extracts data of a desired channel from the input data and applies it to the switching device 64. The switching device 64 identifies whether the broadcast is for normal limited reception or broadcast with CM. In the case of normal broadcast for limited reception, the switching device 64 supplies the data from the separation device 62 to the key separation device 72 and adds the CM. In the case of broadcasting, the program information portion of the output data of the separation device 62 is supplied to the key separation device 72 and the provision information portion is supplied to the digital watermark detector 68.

  The switching device 64 also applies the output data of the separation device 62 to the recording / reproducing device 66 as necessary. The recording / reproducing apparatus digitally records and reproduces input data. The switching device 64 supplies the data reproduced from the recording / reproducing device 66 to the devices 68 and 72 described later, similarly to the output data of the separating device 62.

  The key separation device 72 separates the common information and individual information from the program information supplied from the switching device 64 and the scrambled video information. The former is the key switching device 76 and the latter is the video descrambler position 74. Apply. In addition, the digital watermark detector 68 detects a digital watermark inserted in the CM information, and stores common information and individual information included in the digital watermark in the key information storage device 70. The key switching device 76 selects common information and individual information from the key separation device 72 in the case of normal limited reception broadcasting, and is stored in the key information storage device 70 in the case of broadcasting with CM. The common information and the individual information are selected, and the selected individual information is supplied to the decryption device 78 and the selected common information is supplied to the decryption device 82.

  The decryptor 78 decrypts the individual information using the master key Km held in the receiving device 60 and applies the work key Kw to the decryptor 82. The decryptor 82 decrypts the common information from the key switching device 76 using the work key Kw from the decryptor 78 and applies the scramble key to the video descrambler 74.

  The video descrambler 74 uses the scramble key Ks from the decryptor 82 to release the scrambled video information from the key separator 72 and applies the MPEG compressed video information to the decoder 84. The decoding device 84 decompresses the compressed video information from the video descrambling device 74 and restores the video information. Note that the decryption device 84 performs protection for preventing dubbing on the restored video information, and outputs it.

It is a schematic block diagram of the transmitting side of one embodiment of the present invention. It is a schematic diagram of the transmission timing of the scramble and scramble key Ks of the present embodiment. It is a schematic block diagram of the receiving apparatus of a present Example. It is a schematic block diagram of a prior art example.

Explanation of symbols

10: Transmission device 12: Program bank 14: CM bank 20, 22: Encoding device 24: Control devices 26, 28, 30: Key generation device 32, 34: Encryption device 36: Digital watermark creation device 38: Video scramble device 40: Multiplexer 42: Switching device 44: Buffer memory 46: Digital watermark inserting device 48: Buffer memory 50: Combining device 60: Receiving device 62: Separating device 64: Switching device 66: Recording / reproducing device 68: Digital watermark detector 70 : Key information storage device 72: Key information separation device 74: Video descrambling device 76: Key switching device 78: Decryptor 82: Decryptor 84: Decryptor 110: Transmitter 112: Program information 114: CM information 116 : Switching device 118: Storage device 120: Encoder 122: Video scrambling device 124: Encryption device 126: Encryption 128: multiplexer 130: transmission path 140: reception apparatus 142: separator 144: decryptor 146: decryptor 148: video descrambling device 150: the decoding device

Claims (7)

A transmitter that transmits the second information encrypted with the key information after the first information in which the key information is embedded;
An information transmission system comprising: a receiving device that extracts the key information from the first information and decrypts the encrypted second information with the key information. The information transmission system according to claim 1, wherein the first and second information are digitally broadcast. The information transmission system according to claim 2, wherein the first information includes CM data, and the second information includes program information. The information transmission system according to claim 1, wherein the key information is embedded in the first information as a digital watermark. Generate first information with embedded key information,
Encrypt the second information with the key information,
After the first information in which the key information is embedded, the second information encrypted with the key information is transmitted,
Extracting the key information from the received first information,
An information transmission method, wherein the received second encrypted information is decrypted with the extracted key information. 6. The information transmission method according to claim 5, wherein the first information is composed of CM data, and the second information is composed of program information. The information transmission method according to claim 5, wherein the key information is embedded in the first information as a digital watermark.

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