JP2005149437A - Information distribution system and terminal authentication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information distribution system and a terminal authentication method which makes alteration of content reproduction software by an unauthorized user difficult. <P>SOLUTION: In the information distribution system which distributes software for content reproduction to a terminal at a license requesting origin prior to distribution service of content to the terminal, it is provided with a means for generating a terminal authentication routine in which an identifier of the terminal by which reception of the content is permitted is specified by a private identification value and a relational expression for collating the identifier of the terminal which is going to receive the distributed content with the private identification value is specified and a means for transmitting the software for content reproduction including the terminal authentication routine to the terminal at the license requesting origin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information distribution system and a terminal authentication method, and more particularly to a distribution system for content information such as text, audio, and video, and a terminal authentication method in a content distribution service.

  With the speeding up of communication networks and the advancement of performance of information devices connected to communication networks, content information distribution services such as text, audio, and video via communication networks are becoming more active.

  The content information distribution system includes a content distribution server connected to a communication network and a plurality of user terminals that access the content distribution server via the communication network. In order to transmit content information by efficiently using a limited communication band of the communication network, the content distribution server transmits the data amount of the distribution content in a compressed form using a data compression / decompression algorithm. On the other hand, the user terminal also executes a compression / decompression algorithm corresponding to the compression / decompression algorithm applied on the content distribution server side by hardware or software, returns the compressed content received from the communication network to the original data format, and outputs audio / video. Output to the output device. MPEG (Moving Picture Expert Group) is known as a typical compression / decompression algorithm applied to contents such as music and moving images.

  In a communication network that anyone can easily connect to, such as the Internet, there is an eavesdropping problem in which distribution content is received without permission by a user terminal that the content distribution server does not permit reception of the distribution content. In order to prevent such wiretapping of electronic data on the network, in the content information distribution system, a function of encrypting and transmitting the distribution content and decrypting the content on the receiving side and a content information receiving terminal are permitted in advance. And a terminal authentication function for confirming whether or not the terminal is a new terminal. For this reason, a content distribution service method is adopted in which content reproduction software required by the receiving terminal for decoding the distributed content is distributed in advance from the content distribution server side to the reception-permitted terminal.

  As a method for preventing unauthorized duplication of the above-described content reproduction software in a user terminal, for example, in Japanese Patent Application Laid-Open No. 2001-109719 (Patent Document 1), a content distribution server combines the content reproduction software with the user environment. The identification information and a program for determining compatibility between the content reproduction software and the user environment are distributed to the terminals. In Patent Document 1, before reproducing content on a user terminal, user environment identification information read from the user environment and user environment identification information synthesized with the content reproduction software are compared with each other according to the conformity determination program. If they match, it is determined that the user environment is appropriate, and reading and reproduction of the content data are allowed.

JP 2001-109719 A

  According to the content reproduction software proposed in Patent Document 1, since the user environment to which this reproduction software can be applied is specified by the user environment identification information synthesized in the software, the content reproduction software is copied. Even if an attempt is made to reproduce the content in another user environment (another user terminal) by this duplicate software, there is an advantage that the content reproduction can be prevented due to the mismatch of the user environment identification information.

  However, in the method of the above-mentioned patent document 1, for example, an unauthorized user analyzes the copied content reproduction software, specifies the user environment identification information specified on the server side, and uses this for another terminal adapted to his / her terminal. When the identification information is rewritten, there is a problem that the content reproduction software can be adapted to an unauthorized terminal, and unauthorized content reproduction cannot be prevented.

An object of the present invention is to provide an information distribution system and a terminal authentication method that make it difficult for an unauthorized user to modify content reproduction software.
Another object of the present invention is to provide a content reproduction program that is difficult to be modified by an unauthorized user.

  In order to achieve the above object, the present invention provides an identifier of a terminal that is permitted to receive content in an information distribution system that distributes content reproduction software to a license requesting terminal prior to a content distribution service to the terminal. Means for generating a terminal authentication routine that specifies a relational expression for specifying the identifier of a terminal that intends to receive distribution content and the secret identification value, and content including the terminal authentication routine And a means for transmitting the reproduction software to the license requesting terminal. In addition to the terminal authentication routine, the content reproduction software includes a decryption processing routine for decrypting the encrypted received content and a decompression processing routine for restoring the data-compressed received content. obtain.

  The present invention relates to a terminal authentication method in a content distribution service in which a terminal authentication routine given in advance as a part of software for content reproduction from an information distribution system is executed at a user terminal to determine whether the terminal can receive distribution content. The step of acquiring the identifier of the user terminal and collating the correspondence between the user terminal identifier and the secret identification value of the content reception permitted terminal specified in the terminal authentication routine according to the relational expression specified in the terminal authentication routine And receiving the distribution content from the information distribution system when the correspondence between the user terminal identifier and the secret identification value is authenticated.

  The content reproduction program according to the present invention includes a terminal authentication routine and a routine for restoring the encrypted and / or data-compressed content to the original data. And a description of a relational expression for collating the identifier of the terminal that is to receive or reproduce the content with the secret identification value, and the terminal identifier according to the relational expression And the identifier of the terminal permitted to receive the content are determined, and information indicating the determination result is generated.

  According to one embodiment of the present invention, as the secret identification value, a value obtained by encrypting the identifier of the content reception permitted terminal with a predetermined function is applied. According to another embodiment, a hash value obtained by converting the identifier of the content reception permitted terminal with a predetermined hash function is applied as the secret identification value.

  According to the present invention, the terminal authentication routine specifies the identifier of the terminal permitted to receive the content with the secret identification value, and collates the identifier of the terminal that intends to receive the distribution content with the secret identification value. Since the relational expression is specified, even if the terminal authentication routine is analyzed, it becomes difficult to grasp the identifier value of the content reception permitted terminal from the description content. Therefore, it is possible to prevent illegal content reproduction by modifying the content reproduction software.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration of an information distribution system to which the present invention is applied. The information distribution system is configured by a content server 10 connected to the communication network 5. The terminals 20 (20-1, 20-2,...) Communicate with the content server 10 via the communication network 5, and receive content reproduction software and content information.

  As shown in FIG. 2, each terminal 20 is connected to a processor 21, an audio / video output unit (speaker and display screen) 22, a command and data input unit 23 operated by a user, and an external storage medium. And an external interface 24 for connecting to the communication network 5, a memory 26 for storing programs, a memory 27 for storing data, and a ROM 28.

  The program storage memory 26 is a content server access routine 400, a terminal authentication routine 430, and encrypted content received from the content server 10 as software (programs) related to the present invention executed by the processor 21. A decoding processing routine 440 for decoding and a decompression processing routine 450 for decompressing the content that has been compression-encoded to shorten the data length and returning it to the original data are stored. As will be described later, the terminal authentication routine 430, the decryption processing routine 440, and the decompression processing routine 450 are software distributed as license information from the content server 10 in response to a request from the terminal. The content server access routine 400 includes a content selection routine 410 and a content playback routine 420, which will be described later.

  The data storage memory 27 is used for temporarily storing data processing results by the processor 21, various tables, and content information received from the content server 10. The ROM 28 stores various information essential to the terminal device. A terminal identifier (terminal ID) necessary for the terminal authentication routine 430 is read from the ROM.

FIG. 3 is a block diagram of the content server 10.
The content server 10 includes a processor 11, a network interface 12 for connection to the communication network 5, an input / output unit 13, a program storage memory 14, a data storage memory 15, a content file 16, and a content It consists of a licensed user information management table 17 that stores information on users (licensed users) who are permitted to distribute services.

  The program storage memory 14 stores a content management routine 100, a license management routine 200, a content distribution service routine 300, a data compression routine 320, and a content encryption routine 330 as software related to the present invention. ing. The data storage memory 15 includes a content management table 150, a user information management table 160, a terminal authentication routine 170, a decryption processing routine 180, and an expansion processing routine 190.

FIG. 4 shows a basic program executed in the terminal 20 and the content server 10 and a sequence diagram of the communication message in the content information distribution service.
When the user of the terminal 20 starts the content server access routine 400 and connects the terminal 20 to the content server 10, menu screen information is transmitted from the content server 10 to the terminal 20 (110). To display a menu screen on the output unit 22. When the user designates a content search condition and performs a content list request transmission operation on this menu screen, a content list request message M1 is generated. The request message M1 is transmitted to the content server 10 in a packet format with a packet header (not shown) including the address of the content server 10 as the destination address and the address of the terminal 20 as the transmission source address.

  As shown in FIG. 5A, the content list request message M1 includes a message type 51 indicating that this message is a content list request, and a search condition 52. The search condition 52 includes, for example, content classification (field) information selected on the menu screen and element information such as title, keyword, and period input by the user in combination with a logical operation expression.

  When the content server 10 receives the content list request message M1, the content management routine 100 searches the content management table 150 for content corresponding to the search condition indicated by the received message, and displays the content list message M2 indicating the search result. Transmit to the requesting terminal 20. As shown in FIG. 5B, the content list message M2 is a message list 51 indicating that this message is a content list message, followed by a record number 53 included in this message and a plurality of search results. Attribute records 54 (54-1, 54-2,...) Are included. Each attribute record 54 includes, for example, a content identifier 541, a content name 542, a content classification 543, a price 544, an expiration date 545, and other information 546.

  Upon receiving the content list message M2, the terminal 20 generates a content selection screen that lists the contents of the content attribute record 54, and outputs this to the display screen. When the user selects any content on the content selection screen and requests issuance of license information, a license request message M3 is transmitted from the terminal 20 to the content server 10.

  As shown in FIG. 5C, the license request message M3 includes a message type 51 indicating that this message is a license request message, followed by a content identifier 55, a user identifier 56, password information 57, A terminal identifier 58 is included. The content identifier 55 is the content identifier 541 indicated by the attribute record of the content selected by the user on the content selection screen, and the password information 57 is, for example, a password registered in advance in the content server 10 or a payment account for the content price Is a credit card number. As the terminal identifier 58, the value of the terminal ID read from the ROM 28 is used.

  Upon receiving the license request message M3, the content server 10 performs user authentication by the license management routine 200, generates a license issuance message M4 corresponding to the authentication result, and transmits it to the terminal 20 that is the license request source.

  As shown in FIG. 5D, the license issuance message M4 has a validity indication bit 59 and an attribute of the content to be licensed following the message type 51 indicating that this message is a license issuance message. Information 60, content reproduction software 61, and license number 62 are included. The content attribute information 60 indicates the content of the content attribute record corresponding to the content identifier 55 indicated by the license request message M3. In this embodiment, the content reproduction software 61 includes a terminal authentication routine 170, a content decryption processing routine 180, and a content expansion processing routine 190. The license number 62 indicates, for example, the serial number of the license issue message M4 issued by the license management routine 200.

  The validity display bit 59 is composed of, for example, 32 bits. When the content service is permitted as a result of user authentication, all the validity display bits 59 are “1” and the license including the content software 61 is included. An issue message M4 is generated. When the content service is not permitted, a license issuance message M4 that does not include the content software 60 is generated with all the validity indication bits 59 being “0”.

  When receiving the license issuance message M4, the terminal 20 outputs a message addressed to the user according to the validity display bit 59 as a response result to the license request on the display screen. If the content service is permitted (when all the validity indication bits are “1”), the contents of the content reproduction software 61 of the received message M4 are converted into the terminal authentication routine 430, the decryption processing routine 440, and the decompression processing. Stored in the memory 26 as a routine 450.

  When the user requests content distribution on the response result display screen, the terminal 20 executes the content reproduction routine 420. In the present embodiment, in the content reproduction routine 420, first, the terminal authentication routine 430 (170) obtained by the license issuance message M4 is executed, and when the terminal authentication is successful, a content transmission request message is sent to the content server 10. Issue M5. If the terminal authentication is not successful, the issue of the content transmission request message M5 is suppressed.

  As shown in FIG. 6A, the content transmission request message M5 should be distributed in response to the message type 51 indicating that this message is a content transmission request and the content identifier 55 and this message. A content range 63 and a user identifier 56 are included.

  Upon receiving the content transmission request message M5, the content server 10 executes the content distribution service routine 300. The content distribution service routine 300 refers to the licensed user management information table 17, confirms the validity of the content transmission request message M5, and then is designated by the reception message M5 as shown in FIG. 6B. The designated range of content 70 having the content identifier 55 is read out from the content file 16 in units of blocks (CB-1, CB-2,...) And distributed as content transmission messages M6 to the request source terminal.

  The content transmission message M6 includes a validity indication bit 64, a block number 65, and a content data block 66 following the message type 51 indicating that this message is for content transmission. When the distribution of the content in the transmission range 63 specified by the content transmission request M5 is completed, the content server 10 temporarily ends the content distribution service to the terminal 20 by the content distribution service routine 300, and a new content transmission request from the terminal 20 When M5 is received, the content distribution service is resumed.

Here, a terminal authentication routine 430 to which the present invention is applied will be described with reference to FIGS.
FIG. 7 shows a part of a conventional terminal authentication routine 430P written in C language, and FIG. 8 shows a program flowchart corresponding to FIG. In the conventional terminal authentication routine 430P, the value of the identifier (hereinafter referred to as “permitted terminal ID”) of the terminal permitted by the license management routine 200 for the content distribution service, “0x11223344” is described in the illustrated example.

In the terminal authentication routine 430P, as shown in FIG. 8, the identifier (terminal ID) of the terminal 20 executing this routine is acquired (step 431), and this terminal ID is checked against the permitted terminal ID (433). If the terminal ID matches the permitted terminal ID, the reproduction of the content is permitted (434), and if the terminal ID does not match, the reproduction is not permitted (435).
Therefore, when a malicious user analyzes the terminal authentication routine 430P and rewrites the value of the permitted terminal ID with the value of another terminal ID, it issues a content transmission request from another terminal having the terminal ID. It becomes possible to receive content distribution services illegally.

  In the present invention, in order to prevent the above-described rewriting of the permitted terminal ID, the permitted terminal ID is converted into a secret identification value in the terminal authentication routine. As the secret identification value, for example, a value obtained by encrypting or hash-converting the permitted terminal ID can be applied.

FIG. 9 shows a main part of the terminal authentication routine 430A according to the first embodiment of the present invention, and FIG. 10 shows a flowchart of the terminal authentication routine 430A.
In this embodiment, the license management routine 200 encrypts the permitted terminal ID value (“0x11223344”) by applying a random number, and the terminal authentication routine 430A stores the random number (rand) applied to the encryption. A value, an encrypted permitted terminal ID value (xid), and a decryption operation expression (in this example, an exclusive OR operation) are designated, and the terminal 20 side encrypts the encrypted permission. The terminal ID is decrypted with the random number, the permitted terminal ID is reproduced (432A), and the terminal ID and the reproduced permitted terminal ID are collated (433). According to the present embodiment, the terminal authentication routine 430A does not have a description that directly indicates the value of the permitted terminal ID. Therefore, the terminal authentication routine 430A can be analyzed to illegally grasp the value of the permitted terminal ID. It becomes difficult.

  FIG. 11 shows a flowchart of a terminal authentication routine 430B according to the second embodiment of the present invention. In this embodiment, as in the first embodiment, the license management routine 200 encrypts the permitted terminal ID value (“0x11223344”) using a random number, and the terminal authentication routine 430B applies the above encryption. The specified random number (rand) value, the encrypted permitted terminal ID value (xid), and the encryption formula are specified, and the terminal 20 encrypts the terminal ID with the above random number. An encrypted terminal ID is generated (432B), and the encrypted terminal ID and the encrypted permitted terminal ID designated by the license management routine 200 are collated (433B). According to the present embodiment, since it is not necessary to decrypt the encrypted authorized terminal ID, an irreversible function can be applied as an arithmetic expression for encryption, and safety can be further improved.

FIG. 12 shows a main part of a terminal authentication routine 430C according to the third embodiment of the present invention, and FIG. 13 shows a flowchart of the terminal authentication routine 430C.
In the present embodiment, in the license management routine 200, the value of the permitted terminal ID (“0x11223344”) is converted into a hash value by applying a hash function. In the terminal authentication routine 430C, the hash function (hash) and the permitted terminal are converted. The hash value (hid) of ID is specified. In this case, on the terminal 20 side, the hash function is applied to generate a hash value of the terminal ID (432C), and this hash value is compared with the hash value (hid) of the permitted terminal ID (433C). According to the present embodiment, the terminal authentication routine 430C has no description that directly indicates the value of the permitted terminal ID, and it is difficult to reproduce the original permitted terminal ID from the hash value (hid). Thus, it is possible to further increase the safety of the permitted terminal ID.

FIG. 14 shows a detailed flowchart of the content selection routine 410 executed by the terminal 20.
In response to the content list request input from the user, the content selection routine 410 generates a content list request message M1 and transmits it to the content server 10 (step 411). When the content list message M2 is received from the content server (412), the content attribute content of the received message is output to the display screen as a content selection screen (413), and waits for the user to specify the content and input a license request. (414). When the license request is input, a license request message M3 is generated and transmitted to the content server 20 (415). When the license issue message M4 is received from the content server (416), a guidance message corresponding to the validity display bit of the received message is output to the display screen (417), and the validity display bit indicates permission of the content service. If it is (418), the content reproduction software is extracted from the received message and stored in the memory (419).

FIG. 15 shows a detailed flowchart of the content management routine 100 executed by the content server 10.
In the content management routine 100, the search condition is extracted from the content list request message M1 received from the terminal (101), the entry corresponding to the search condition is searched from the content management table 15 (102), and the content is searched from the searched entry. The attribute information is extracted to generate a content list message M2, which is sent to the terminal to the request source (103).

FIG. 16 shows a detailed flowchart of a license management routine 200 executed by the content server 10 when the license request message M3 is received.
The license management routine 200 refers to the user information management table 160 based on the user identifier 56 indicated by the license request message M3, checks the password 57, and determines whether the content distribution service can be permitted for the license requesting user. User authentication is performed (201).

  As a result of the user authentication (202), if content distribution can be permitted, the license generation process 210 described in FIG. 17 is executed, and then a license issuance message M4 having all validity indication bits “1” is generated. Is transmitted to the license requesting terminal 20 (220). On the other hand, if content distribution cannot be permitted as a result of user authentication, a license issuance message M4 having all validity indication bits of “0” is generated and transmitted to the request source terminal 20 (221).

FIG. 17 shows a detailed flowchart of the license generation process 210.
In the license generation process 210, the content management table 15 is referred to based on the content identifier 55 specified in the license request message M3, content attribute information corresponding to the content identifier 55 is acquired, and this content attribute information is added to the license issuance message M4. Information 60 is set (211). Next, the terminal authentication routine 170 is read from the memory 15, and the secret identification value of the permitted terminal ID obtained by encrypting the ID 58 of the request message terminal M3 into an encrypted or cache value is inserted, and this is used for the content reproduction software 61. As the terminal authentication routine 170, the license issuance message M4 is set (211).

  Further, the decryption processing routine 180 and the decompression processing routine 190 corresponding to the content identifier 55 are read from the memory 15, and these are set in the license issuance message M4 as the decryption processing routine 180 and the decompression processing routine 190 for the content reproduction software 61 (213). 214), a new serial number is generated and used as the license number 62 of the license issue message M4 (215). Thereafter, the correspondence relationship between the content identifier 55, the user identifier 56, and the license number 62 is stored in the licensed user information management table 17 (216), and this routine is terminated.

FIG. 18 shows a detailed flowchart of a content distribution service routine 300 executed by the content server 10 in response to the content transmission request message M5.
In the content distribution service routine 300, the licensed user information management table 17 is referred to, and whether or not the correspondence relationship between the coin content identifier 55 and the user identifier 56 indicated by the content transmission request message M5 is permitted by the license management routine 200. Is checked (301).

  If it is determined by the above check that the content distribution service is possible (302), the content data in the content range 63 specified by the request message M5 is sequentially read from the content file 16 in units of blocks (303), and this is validated. The content transmission message is transmitted to the requesting terminal 20 as a content transmission message M6 in which all bits of the sex indication bit are set to “1” (304). It is determined whether or not the transmitted content data block is the last block in the designated range 63 (305). If not, the steps 303 to 305 are repeated.

  If the transmitted content block is the last block in the specified range 63, a message indicating the end of content transmission is transmitted to the request source terminal (306), and this routine is terminated. If it is determined in step 302 that the content distribution service is not possible, a content transmission request message M5 in which all the validity display bits are “0” and does not have the block number 65 and the content block 66 is generated. This is transmitted to the requesting terminal 20 (307), and this routine is terminated. The content transmission end message may be, for example, a specific number indicating the end of data in the block number 65, for example, a content transmission message M6 in which all bits are set to “1”.

FIG. 19 shows a detailed flowchart of a content playback routine 420 executed on the terminal 20.
In the content reproduction routine 420, the terminal authentication routine 430 distributed in response to the license request is executed to determine whether the terminal authentication is successful (421). If the terminal authentication is not successful, an error message is output on the display screen (429), and this routine is terminated. If the terminal authentication is successful, a content transmission request message M5 is generated and transmitted to the content server 10 (422).

  When the content transmission message M6 is received from the content server 10 (423), the validity indication bit of the received message is determined (424). If all the validity display bits are "0", an error message is output on the display screen (429), and this routine is terminated. If all the validity indication bits are “1”, it is determined whether or not the received message is a content transmission end message (425), and if it is a content transmission end message, this routine is ended.

  If the received message is not a content transmission end message, the received content block is decrypted by the decryption processing routine 440 (426), and the decrypted content block is decompressed by the decompression processing routine 450 (427). Data is output to the audio / video output unit 22 (428), and the next content transmission message M6 is awaited in step 423. A plurality of buffer areas for holding the expanded content data are prepared in the memory 27, and data is output from the buffer area to the audio / video output unit 22 by switching the buffer area for each content block. In addition, the new content data conversion processing by the above-described decryption processing routine and decompression processing routine can be executed in parallel.

  As is clear from the above embodiments, according to the present invention, in the terminal authentication routine distributed from the content server to the terminal as the content reproduction software, the secret identification that is difficult for the user to grasp the value of the permitted terminal identifier directly is difficult. Because it is specified by value, a user who has not received a license illegally uses the content playback software distributed to other users and rewrites the permitted terminal identifier in the terminal authentication routine to obtain the distributed content illegally. It is possible to prevent this.

  In the embodiment, the three functions of the content management function, the license management function, and the content distribution service function are concentrated on one server (content server 10), and the content list request, license request, and content transmission request from the user terminal are all described above. Although the system configuration is that processing is performed by the content server, the information distribution system of the present invention may have a system configuration in which these functions are distributed to a plurality of servers.

  For example, in an information distribution system comprising a license server 10A that accepts a content list request and a license request and a content distribution server 10B that accepts a content transmission request, the license server 10A sends a license issuance message M4 transmitted in response to the license request. For example, as indicated by a broken line in FIG. 5D, the address (content server address) 68 of the content distribution server 10B is notified to the requesting terminal 20, and the terminal 20 specifies the content server address 68. The content transmission request M5 may be transmitted to the server that has been made.

  In this case, the content file and the licensed user information management table 17 shown in FIG. 3 are provided on the content distribution server side, and when the license server 10A issues the license issue message M4, the licensed user information management table is displayed. 17 notifies the content distribution server 10B of information to be registered, and the server 10B determines whether or not the content transmission request M5 can be accepted by referring to the licensed user information management table 17 when receiving the content transmission request M5. It can be so.

  In the embodiment, the operation in the case where the content reproduction routine 420 outputs the content distributed from the content server to the audio / video output unit in real time has been described. However, the terminal user loads the received content into the specified file name. When the content transmission request in the mode to be input is input, steps 426 and 427 in FIG. 19 may be omitted, and the received content block may be stored in the designated file in step 428.

  The present invention can also be applied to a broadcast type information distribution system that broadcasts distribution content to a plurality of terminals for which a content server has obtained a license. In the broadcast-type information distribution system, each terminal only needs to receive content that is currently being broadcast by the content server. Therefore, the content reproduction processing routine 420 receives a content reproduction request in place of the above-described content transmission request from the user. When the terminal authentication routine 430 is executed and the terminal authentication is unsuccessful, the distribution content is rejected. When the terminal authentication is successful, the broadcast content is received and the received content is decrypted. The decompression / output process may be executed.

The figure which shows the information delivery system with which this invention is applied. The block block diagram which shows one Example of the terminal 20 shown in FIG. The block block diagram which shows one Example of the content server 10 shown in FIG. The figure which shows the sequence of the basic program and communication message which are performed with the terminal 20 and the content server 10 in a content information service. The figure which shows the format of the messages M1-M4 communicated between the terminal 20 and the content server 10. FIG. The figure which shows the format of the content transmission request message M5 which the terminal 20 issues, and the content transmission message M6 transmitted from the content server 10. FIG. The figure which shows the principal part of the conventional terminal authentication routine 430P described in C language. The program flowchart corresponding to FIG. The figure which shows the principal part of the terminal authentication routine which shows one Example of this invention described in C language. The program flowchart corresponding to FIG. The program flowchart of the terminal authentication routine principal part which shows the other Example of this invention. The figure which shows the principal part of the terminal authentication routine which shows the further another Example of this invention described in C language. The program flowchart corresponding to FIG. 5 is a flowchart showing details of a content selection routine 410 executed by the terminal 20. 4 is a flowchart showing details of a content management routine 100 executed by the content server 10. 5 is a flowchart showing details of a license management routine 200 executed by the content server 10. 5 is a flowchart showing details of a license generation process 210 in the license management routine 200. 5 is a flowchart showing details of a content distribution service routine 300 executed by the content server 10. 14 is a flowchart showing details of a content reproduction processing routine 3420 executed by the terminal 20.

Explanation of symbols

5: communication network, 10: content server, 11: processor, 12: network interface, 13: input / output device, 16: content file, 17: licensed user information management table, 20: terminal, 21: processor, 22: Audio / video output section,
23: input / output unit, 24: external interface, 25: network interface,
100: Content management routine, 150: Content management table, 160: User information management table, 170, 430: Terminal authentication routine, 180, 440: Decryption processing routine, 190, 450: Decompression processing routine, 200: License management routine,
300: Content distribution service routine, 320: Data compression routine,
330: Data encryption routine, 400: Content server access routine.

Claims (8)

Prior to the content distribution service to the terminal, in the information distribution system that distributes the content reproduction software to the license requesting terminal,
A terminal authentication routine is generated in which the identifier of a terminal that is permitted to receive content is designated by a secret identification value, and a relational expression for collating the identifier of the terminal that intends to receive distribution content with the secret identification value is designated. Means,
An information distribution system comprising: means for transmitting content reproduction software including the terminal authentication routine to a license requesting terminal.   The content reproduction software includes, in addition to the terminal authentication routine, a decryption processing routine for decrypting the encrypted received content and a decompression processing routine for restoring the data-compressed received content. The information distribution system according to claim 1.   3. The information distribution system according to claim 1, wherein the generation unit of the terminal authentication routine uses, as the secret identification value, a value obtained by encrypting an identifier of the content reception permission terminal with a predetermined function. .   3. The terminal authentication routine generating means uses the hash value obtained by converting the identifier of the content reception permitted terminal with a predetermined hash function as the secret identification value. The information distribution system described. In a content distribution service for executing a terminal authentication routine given in advance as a part of content reproduction software from an information distribution system at a user terminal before receiving distribution content and determining whether the terminal can receive distribution content In the terminal authentication method,
Obtaining an identifier of the user terminal;
Checking the correspondence between the user terminal identifier and the secret identification value of the content reception permitted terminal specified in the terminal authentication routine according to the relational expression specified in the terminal authentication routine,
A terminal authentication method in a content distribution service, wherein when a correspondence relationship between the user terminal identifier and the secret identification value is authenticated, reception of distribution content from the information distribution system is permitted.   6. The terminal authentication method in the content distribution service according to claim 5, wherein a value obtained by encrypting an identifier of the content reception permitted terminal with a predetermined function is applied as the secret identification value.   6. The terminal authentication method in the content distribution service according to claim 5, wherein a hash value obtained by converting an identifier of the content reception permitted terminal with a predetermined hash function is applied as the secret identification value. Content playback executed on a terminal that can be connected to a content distribution system via a network, comprising a terminal authentication routine and a routine for restoring encrypted and / or data-compressed content to the original data A program,
The terminal authentication routine includes a secret identification value indicating a terminal that is permitted to receive content, and a description of a relational expression for collating the terminal identifier and the secret identification value. A content reproduction program characterized by determining the identity of a terminal identifier and a content reception permitted terminal identifier and generating information indicating the determination result.

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