JP2013034240A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter and a receiver which allow fine-grained usage control of content data using copy control information.SOLUTION: A transmitter comprises: first transmission means for transmitting format information which indicates a format of content data, in plaintext to a receiver which is a transmission destination of the content data; encryption means for encrypting the content data using an encryption parameter according to the format of the content data and common secret information shared with the receiver; and second transmission means for transmitting the content data encrypted by the encryption means to the receiver.

Description

  The present invention relates to a transmission apparatus.

  There is DTCP-IP (Digital Transmission Content Protection over Internet Protocol) as a technical standard for transmitting content data protected by copyright protection technology (DRM: Digital Rights Management) in an IP network such as a home LAN. According to DTCP-IP, the content data is encrypted and transmitted to the IP network, so that unauthorized copying of the content data due to packet wiretapping can be prevented.

  By the way, DTCP-IP does not define a method for transmitting the format of content data transmitted / received between a transmission device and a reception device. Therefore, when transmitting content data by MPEG-TS (Moving Picture Experts Group Transport System), DTLA (Digital Transmission Licensing Administrator) sets DTCP_descriptor describing content data copy control information, usage rules, etc. (Embedded CCI). A rule for inserting and transmitting data is established (see Non-Patent Document 1). Thereby, the receiving device that receives the content data can control the use of the content data with reference to the DTCP_descriptor inserted into the content data.

Digital Transmission Content Protection Volume 1 Supplement E Revision 1.2 (Informational Version), P.28-31 V1SE.7 Modification to Appendix B (DTCP_descriptor for MPEG Transport Stream)

  However, in the technique described in Non-Patent Document 1, when content data is transmitted in a format other than MPEG-TS, the format of the content data into which Embedded CCI is inserted has not been established. There is a problem that Embedded CCI can only be inserted in a limited area such as a portion, and the content data can be more precisely controlled by Embedded CCI than in MPEG-TS, and the convenience for the user is low.

  The present invention has been made in view of the above, and an object of the present invention is to provide a transmission apparatus that can safely perform fine usage control of content data based on copy control information.

  In order to solve the above-described problems and achieve the object, the present invention provides first transmission means for transmitting format information indicating a format of content data to a receiving device to which the content data is transmitted, in plain text, Encrypting means for encrypting the content data using encryption parameters corresponding to shared secret information shared with the receiving apparatus and the format of the content, and the receiving apparatus encrypting the content data encrypted by the encrypting means And a second transmitting means for transmitting to.

  According to the present invention, there is an effect that fine usage control of content data by copy control information can be executed safely.

It is a block diagram which shows the structure of a content transmission system. It is a block diagram which shows the hardware constitutions of the transmitter concerning 1st Embodiment, and a receiver. It is a block diagram which shows the function structure of the transmitter concerning 1st Embodiment. It is a flowchart which shows the procedure of the transmission process of the content data by the transmission apparatus concerning 1st Embodiment. It is a figure which shows an example of shared public information. It is a block diagram which shows the function structure of the receiver concerning 1st Embodiment. It is a flowchart which shows the procedure of the reception process of the content data by the receiver concerning 1st Embodiment. It is a figure which shows an example of the packet of the encryption content data in which shared public information was inserted. It is a figure which shows an example of exclusive command data.

  Exemplary embodiments of a transmission apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. In this embodiment, an example in which content data is transmitted and received between personal computers connected via a network will be described, but the present invention is not limited to this. For example, the present invention can also be applied when content data is transmitted and received between a personal computer and an AV device (for example, an audio device or a video device) connected via a network.

(First embodiment)
First, a content transmission system including a transmission device and a reception device according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a content transmission system.

  A content transmission system 100 shown in FIG. 1 is transmitted from a transmission apparatus 101 and a transmission apparatus 101 that transmit content data obtained by encrypting plaintext (unencrypted) content data (hereinafter referred to as encrypted content data). A receiving device 102 that receives the encrypted content data, and a network 103 such as a LAN that transmits the encrypted content data transmitted from the transmitting device 101 to the receiving device 102.

  Next, the hardware configuration of the transmission apparatus 101 and the reception apparatus 102 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a hardware configuration of the transmission device and the reception device according to the present embodiment.

  As illustrated in FIG. 2, the transmission device 101 and the reception device 102 are, for example, personal computers, and include a CPU (Central Processing Unit) 201 that is a main part of the personal computer and controls each unit centrally. The CPU 201 is connected to a ROM (Read Only Memory) 202 which is a read only memory storing BIOS and a RAM (Random Access Memory) 203 which stores various data in a rewritable manner through a bus 204.

  Further, the bus 204 includes an HDD (Hard Disk Drive) 205 that stores content data set with copy control information and various programs, and a CD (Compact) as a mechanism for reading computer software that is a distributed program. Disc) -ROM 206, a CD-ROM drive 207, a communication control unit 208 that controls communication between the transmission device 101 and the reception device 102 and the network 103, an input unit 209 such as a keyboard and a mouse for performing various operation instructions, and various types A display unit 210 such as a CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display) for displaying information and an audio output unit 211 such as a speaker or headphones for outputting sound are connected via an I / O (not shown). ing.

  Since the RAM 203 has a property of storing various data in a rewritable manner, it functions as a work area for the CPU 201 and functions as a buffer. The RAM 203 is information shared by device authentication or the like between the transmission apparatus 101 and the reception apparatus 102. For example, the shared secret such as an encryption key, a secret parameter, and a random number used for encryption and decryption by a common key method. Store information.

  Note that in this embodiment, an example in which encrypted content data encrypted by the common key method is transmitted and received between the transmission apparatus 101 and the reception apparatus 102 is described, but the present invention is not limited to this. For example, a public key method using different keys for encryption and decryption can be used. In this case, the encryption key means a decryption key.

  The CD-ROM 206 implements the storage medium of the present invention, and stores an OS (Operating System) and various programs. The CPU 201 reads the program stored in the CD-ROM 206 with the CD-ROM drive 207 and installs it in the HDD 205.

  As the storage medium, not only the CD-ROM 206 but also various types of media such as semiconductor memory, various optical disks such as DVD (Digital Versatile Disk), various magnetic disks such as various magneto-optical disks and flexible disks, and the like are used. be able to. Alternatively, the program may be downloaded from the network 103 via the communication control unit 208 and installed in the HDD 205. In this case, the storage device storing the program in the server on the transmission side is also a storage medium of the present invention. Note that the program may operate on a predetermined OS, and in that case, the OS may take over the execution of some of the various processes described later, It may be included as a part of a group of program files constituting the OS or the like.

  The CPU 201 that controls the operation of the entire system executes various processes based on a program loaded on the HDD 205 used as the main storage device of the system.

  Next, among the functions that the various programs installed in the HDD 205 of the transmission apparatus 101 and the reception apparatus 102 cause the CPU 201 to execute, characteristic functions provided in the transmission apparatus 101 and the reception apparatus 102 according to the present embodiment will be described. .

  First, the functional configuration of the transmission apparatus 101 and the procedure of content data transmission processing by the transmission apparatus 101 will be described with reference to FIGS. 3 and 4. FIG. 3 is a block diagram showing a functional configuration of the transmission apparatus according to this embodiment. FIG. 4 is a flowchart showing a procedure of content data transmission processing by the transmission apparatus according to the present embodiment.

  As illustrated in FIG. 3, the transmission apparatus 101 implements a disclosure unit 301, a determination unit 302, an encryption unit 303, and a transmission unit 304 by following a program installed in the HDD 205.

  The disclosure unit 301 functions as a UPnP (Universal Plug and Play) CDS (Content Directory Service), and shares information related to each piece of content data that can be received by the receiving apparatus 102 as information that is publicly disclosed to each apparatus on the network 103. The public information is disclosed (transmitted) to the receiving device 102 in plain text. In the present embodiment, it is assumed that the disclosure unit 301 publishes (transmits) meta information including attribute information of content data including the shared disclosure information to the receiving apparatus 102.

  Here, the shared public information includes an arbitrary character string representing the format information of the content data in which the copy control information is set. FIG. 5 is a diagram illustrating an example of shared public information. In the shared public information shown in FIG. 5, “COMPANY_A.CO.JP_CONTENT_FORMAT =“ companyA.co.jp/mpeg-ps ”” is format information for specifying the format of the content data. The "COMPANY_A.CO.JP" or "companyA.co.jp" part of this shared public information is a unique name (for example, an Internet domain name) applied to some organization, and identifies the format of the content data Is a unique identifier. In this case, it means that the format is determined by the company “COMPANY_A”.

  The determination unit 302 determines an encryption key used for encrypting the content data acquired from the shared public information disclosed by the public unit 301 and the shared secret information stored in the RAM 203 (step S401).

  In the present embodiment, the determination unit 302 uses “COMPANY_A.CO.JP_CONTENT_FORMAT =“ companyA.co.jp/mpeg-ps ””, which is an arbitrary character string representing the format information of content data, and the shared secret information. The encryption key shall be determined. Note that the determination unit 302 generally calculates a hash value, which is a numerical value representing this character string, using a hash function, and determines an encryption key from the calculated hash value and shared secret information.

  The copy control information is CCI (Copy Control Information) for controlling the use of content data. For example, “Copy Free”, “Copy Once”, “Copy No More”, “Copy Never”, etc. Includes segments. For “Copy Free” etc., the content data can be copied freely, only one copy is permitted, no copy is permitted (move is permitted), and neither copy nor move is permitted. Is expressed.

  Also, the determination unit 302 may determine the encryption key using the time change constant that changes in common at every predetermined time or every transmission of the encrypted content data in the transmission device 101 and the reception device 102 as the shared public information. good.

  The encryption unit 303 encrypts the content data stored in the HDD 205 with the encryption key determined by the determination unit 302 (for example, the public key in the case of the public key method, the common key in the case of the common key method). Encrypted encrypted content data is generated (step S402).

  The transmission unit 304 transmits the encrypted content data generated by the encryption unit 303 to the reception device 102 via the communication control unit 208 (step S403).

  Next, the functional configuration of the reception apparatus 102 and the procedure of content data reception processing by the reception apparatus 102 will be described with reference to FIGS. 6 and 7. FIG. 6 is a block diagram showing a functional configuration of the receiving apparatus according to this embodiment. FIG. 7 is a flowchart showing a procedure of content data reception processing by the reception apparatus according to the present embodiment.

  As illustrated in FIG. 6, the reception apparatus 102 implements an acquisition unit 601, a reception unit 602, a determination unit 603, a decoding unit 604, and a reproduction unit 605 by following a program installed in the HDD 205.

  The acquisition unit 601 acquires / receives plaintext shared public information that is publicly disclosed to each device on the network 103 by the UPnP CDS of the transmission device 101. In the present embodiment, it is assumed that acquisition unit 601 acquires / receives shared public information from meta information indicating the attribute of content data.

  First, the receiving unit 602 receives the encrypted content data transmitted from the transmitting apparatus 101 via the communication control unit 208 (step S701).

  The determination unit 603 stores the shared public information including the format information acquired by the acquisition unit 601 (part of “COMPANY_A.CO.JP_CONTENT_FORMAT =“ companyA.co.jp/mpeg-ps ”illustrated in FIG. 5) and the RAM 203. The shared secret information that has been encrypted and the encryption key used to encrypt the encrypted content data received from the shared secret information are discriminated (step S702).

  The decryption unit 604 generates content data by decrypting the encrypted content data received by the reception unit 602 with the encryption key determined by the determination unit 603 (step S703).

  The reproduction unit 605 indicates the content data generated by the decryption unit 604 as “COMPANY_A.CO.JP_CONTENT_FORMAT =“ companyA.co.jp/mpeg-ps ”” shown in FIG. 5 which is the format information included in the public disclosure information. The content data in the format is reproduced according to the copy control information set in the content data (step S704). For example, the format indicated by “COMPANY_A.CO.JP_CONTENT_FORMAT =“ companyA.co.jp/mpeg-ps ”” indicates that the copy control information is set in the content data with MPEG_PS defined by the company named COMPANY_A. The reproduction unit 605 reproduces the content data generated by the decoding unit 604 as MPEG_PS content data defined by the company named COMPANY_A according to the copy control information set in the content data.

  As described above, according to the transmitting apparatus 101 and the receiving apparatus 102 according to the present embodiment, the content data is encrypted by using the shared public information including the format information of the content data, and is disclosed to the receiving apparatus 102. If the shared public information is tampered with, the encrypted content data received by the receiving device 102 cannot be correctly decrypted, so the content using the transmission method in which the format for inserting the copy control information is not established. Even when data is transmitted, fine usage control of content data based on copy control information, such as preventing unauthorized copying of content data, can be performed safely.

(Second Embodiment)
This embodiment is an example in which shared public information is provided in the header portion of a packet for transmitting encrypted content data over a network. The description of the same configuration as that of the first embodiment is omitted, and only the configuration different from that of the first embodiment will be described.

  The disclosure unit 301 inserts the shared disclosure information into the header portion of the packet for transmitting the encrypted content data over the network 103 and publishes (transmits) the shared disclosure information to the receiving device 102. The public unit 301 may insert shared public information including different format information for each packet of encrypted content data. In the present embodiment, an example in which shared public information is inserted into the header portion of a packet will be described, but the present invention is not limited to this. For example, the shared public information may be inserted at a predetermined position in the payload portion that is the data body of the packet.

  FIG. 8 is a diagram illustrating an example of a packet of encrypted content data into which shared public information is inserted. As shown in FIG. 8, the packet transmitted by the transmission unit 304 includes a header portion (“Header”) and a payload (“Payload”) that is data obtained by dividing encrypted content data into packets. Configured.

  The header portion includes a packet type that is information for identifying a packet transmitted on the network 103, a header size of the header portion included in the packet, and an encryption mode indicating an encryption method used for generating encrypted content data. , Shared secret information label for identifying the shared secret information used to determine the encryption key, time-varying constant used to determine the encryption key, variable-length shared public information that is the size of the shared public information inserted in the header part Assume that variable-length shared public information, which is shared public information including size and format information, and the data size of encrypted content data are inserted.

  In addition to the format information (“company_a.co.jp/mpeg-ps;”), the disclosure unit 301 uses a usage rule (“copy_control_information = NMC; effective_period”) that is an arbitrary character string representing a rule regarding the use of content data. Shared public information (“company_a.co.jp/mpeg-ps;copy_control_information=NMC;effective_period=1Week”) further including (= 1Week ”) can be disclosed (inserted into the packet).

  Here, “company_a.co.jp/mpeg-ps;” indicates that this is a content data compression method of the standard defined by the company company_a. “Copy_control_information = NMC;” indicates that the copy control information is NMC (No More Copy). “Effective_period = 1Week” stipulates that the usable period of content data is one week.

  The acquisition unit 601 acquires / receives shared public information inserted in the header portion of the packet. In addition to the format information, the acquisition unit 601 can also acquire shared public information including usage rules from the header portion of the packet. Note that the configuration of the packet transmitted over the network 103 is the same as the configuration shown in FIG.

  The playback unit 605 plays back the content data generated by the decryption unit 604 according to the usage rules included in the shared public information inserted in the header portion of the packet.

  As described above, according to the transmission apparatus 101 and the reception apparatus 102 according to the present embodiment, the format information can be changed for each packet transmitted on the network 103.

  In addition, by encrypting the content data using the shared public information including an arbitrary character string representing the usage rule of the content data, the arbitrary character string representing the usage rule included in the shared public information during packet transmission Is altered, the content data cannot be correctly decrypted by the receiving apparatus 102, so that finer usage control of the content data based on the copy control information can be executed safely.

(Third embodiment)
The present embodiment is an example in which the shared public information is disclosed to the receiving device by using dedicated command data inserted in the payload portion. The description of the same configuration as that of the first embodiment is omitted, and only the configuration different from that of the first embodiment will be described.

  The public unit 301 refers to the encrypted command data transmitted on the network 103 via the communication control unit 208 by using the dedicated command data in which the shared public information is inserted in the payload portion (hereinafter referred to as dedicated command data). The shared public information is made public by transmitting to another receiving channel 102 via another communication channel.

  FIG. 9 is a diagram illustrating an example of dedicated command data. As shown in FIG. 9, the dedicated command data transmitted by the disclosure unit 301 includes a payload (“Payload”) that is a data body of the dedicated command data.

  The payload includes a shared secret information label for identifying the shared secret information used to determine the encryption key, a time change constant used to determine the encryption key, a variable-length shared public information size that is the size of the shared public information, and It is assumed that variable-length shared public information (“company_a.co.jp/mpeg-ps;copy_control_information=NMC;effective_period=1Week”) that is shared public information is inserted.

  Although not included in the dedicated command data shown in FIG. 9, in order to improve the security strength, a mechanism for detecting falsification between the transmission apparatus 101 and the reception apparatus 102 is used, for example, a message for shared public information An authentication code (MAC: Message Authentication Code) may be added.

  The acquisition unit 601 acquires / receives shared public information from dedicated command data received from the transmission apparatus 101 through a communication channel different from encrypted content data transmitted over the network 103. The configuration of the packet transmitted on the network 103 is the same as the configuration shown in FIG.

  As described above, according to the transmission apparatus 101 and the reception apparatus 102 according to the present embodiment, when the dedicated command data transmitted through a communication channel different from the encrypted content data is falsified, the reception apparatus 102 correctly Since it becomes impossible to decrypt the content data, fine usage control of the content data based on the copy control information can be executed safely.

DESCRIPTION OF SYMBOLS 101 Transmission apparatus 102 Reception apparatus 103 Network 301 Disclosure part 302 Determination part 303 Encryption part 304 Transmission part 601 Acquisition part 602 Reception part 603 Determination part 604 Decoding part 605 Reproduction part

Claims (6)

First transmission means for transmitting, in plain text, format information indicating a format of content data to a receiving device that is a transmission destination of the content data;
Encryption means for encrypting the content data using encryption parameters corresponding to the shared secret information shared with the receiving device and the format of the content;
Second transmission means for transmitting the content data encrypted by the encryption means to the receiving device;
A transmission device comprising:   The first transmission means inserts the format information at a predetermined position in a packet for transmitting the encrypted content data over a network, and transmits the format information to the receiving device. Item 2. The transmission device according to Item 1.   The transmission apparatus according to claim 2, wherein the first transmission unit inserts the format information into a header portion of the packet and transmits the format information to the reception apparatus.   The transmission apparatus according to claim 1, wherein the first transmission unit transmits the format information to the reception apparatus as information that is publicly disclosed to each apparatus on the network.   The said 1st transmission means transmits the dedicated command data in which the said format information was inserted in the payload part to the said receiving device, and transmits the said format information to the said receiving device. Transmitter device.   The said 1st transmission means transmits the information showing the usage rule regarding utilization of the said content data to the said receiving device in addition to the said format information, The one of Claim 1 to 5 characterized by the above-mentioned. Transmitter device.

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