JP2008165486A - Content distribution system, control program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encryption system for flexibly setting secrecy by setting the number of release keys corresponding to the secrecy of content. <P>SOLUTION: This content distribution system includes a key information generation means for generating key information for decoding the other content; a management information storage means for storing management information including the key information; a first encryption means (S303) for encrypting specific content on the basis of the key information of the management information; a reference information generation means for specifying one or more distributed content for reference which has been distributed before, and for generating reference information for reading one or more key information included in the content for reference; and a content preparation means (S304) for preparing content for distribution on the basis of the encrypted specific content and the reference information and other key information for decoding content to be distributed after the specific content. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to content processing of a content distribution system.

  Conventionally, in this type of system, the following encryption / decryption method is disclosed in the public / private key system.

  In the first encryption / decryption method, private key information is sent to the receiving side (decoding side) in advance by some method. In the second encryption / decryption method, the sending side encrypts data with the public key.

In the third encryption / decryption method, the receiving side decrypts data with a private key.

  Further, the following Patent Document 1 discloses the following encryption / decryption method.

In the fourth encryption / decryption method, different keys are prepared according to different parts in the content. In the fifth encryption / decryption method, key information is incorporated into the content. In the sixth encryption / decryption method, it is described that decryption is performed with a key corresponding to each part and reproduction.
JP 2005-284525 A

  However, the first encryption / decryption method has the following problems.

  In other words, if the private key is known, the cryptographic process itself does not make sense. Moreover, it is necessary to send an individual public key in advance (two-way exchange is required).

  In the second encryption / decryption method, since the content itself contains all the keys for decrypting the content, if the specific content is captured by monitoring the network and the specific key is decrypted, the corresponding specific If the part can be decrypted immediately and each part of the key is difficult to decrypt, there is a problem that it takes a long time to reproduce the content or the load on the reproducing apparatus increases.

  The present invention has been made to solve the above problems, and the object of the present invention is to enable decryption only by using a plurality of keys embedded in a plurality of contents received and stored in advance. Therefore, an object of the present invention is to provide an encryption system in which the number of keys corresponding to the confidentiality of content can be set and the secrecy can be set flexibly.

  The present invention relates to a key information generating unit that generates key information for decrypting other content incorporated into content, and a management information storage for storing information for specifying the content and management information including the key information Means, a first encryption means for encrypting the specific content based on the key information of the management information, and the key information used when encrypted by the other first encryption means. One or a plurality of reference contents distributed previously are required to decrypt the specific contents, and reference information for reading one or a plurality of key information included in the reference contents is generated. Based on reference information generating means, the encrypted specific content, the reference information, and another key information for decrypting the content distributed after the specific content A content creation / distribution device comprising content creation means for creating cloth content, distribution means for distributing the distribution content to another device, receiving means for receiving the specific content, and storing the specific content Based on the storage means and the reference information incorporated in the fixed content, the one or more key information included in the one or more other previously received contents stored in the storage means is read and specified. The content decrypting apparatus includes a first decryption unit that decrypts the content.

  The content creation / distribution device may further include a second encryption unit that encrypts at least one of the decryption key information and the reference information, and the content decryption device includes the decryption key information or The apparatus further comprises second decoding means for decoding at least one of the reference information.

  As described above, according to the present invention, key information is read out from other content that has been previously received and stored based on the reference information included in the content and decrypted, so only specific content has been intercepted. Then you can not decipher.

(It is very expensive to capture and store packets continuously for a long period of time.)
Further, since the user side does not need to perform an operation at the time of decryption, confidentiality can be maintained without an operational load.

  Furthermore, in the case of a plurality of reference contents, particularly contents distributed a long time ago, the embedded key is requested, the reference information and key information are encrypted, or dummy information is mixed with the reference information and key information. By reproducing different key information for each individual, the encryption strength can be increased flexibly and significantly.

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

  FIG. 1 is a diagram showing an encryption system configuration according to the embodiment of the present invention.

  The transmission side terminal 1 and the reception side terminal 2 are, for example, personal computers, and deliver content from the transmission side terminal to the reception side terminal via a mail server. The transmitting side terminal 1 and the receiving side terminal 2 are connected so as to be accessible via the Internet 5.

  In this embodiment, the electronic mail system is described. However, as shown in other embodiments described later, the present invention can be similarly applied to a file transfer (for example, using PPP protocol or FTP protocol) or a transfer system using messaging software. .

  The hard disk 3 of the transmission side terminal 1 stores a so-called mailer including mail address information (address group name and each mail address included in the group), a content distribution side program, an encryption key database, and a selection condition table. When the mailer is activated, the CPU loads the mailer and the content distribution side program into the RAM and displays the initial screen of the mailer. The mailer and the content distribution side program cooperate to execute processing. The content distribution side program may be a mailer plug-in. Here, the content distribution side program is composed of a program 1-3 that performs encryption key creation and encryption key management, a reference information creation program, an encryption processing program 1-1, data, and an encryption key transmission program 1-4. The

  The hard disk 4 of the receiving terminal 2 stores a so-called mailer, a content receiving program, and a received content table. When the mailer is activated, the mailer and the content receiving program are loaded into the RAM and the initial screen of the mailer is displayed. To do. The content receiver program may be a mailer plug-in. Here, the content receiving side program includes a composer 2-3, a received content management unit 2-4, and a decryption processing program 2-2.

  FIG. 2 is a diagram showing a hardware configuration of the distribution side terminal and the reception side terminal in the embodiment of the present invention.

  In FIG. 2, a CPU 21, a RAM 22, a ROM 23, a LAN adapter 24, a video adapter 25, a keyboard 26, a mouse 27, a hard disk 28, and a CD-ROM drive 29 are connected to each other via a system bus 20.

  The system bus 20 means, for example, a PCI bus, an AGP bus, a memory bus, and the like. Further, in FIG. 2, a connection chip between each bus, a keyboard interface, and an input / output interface such as a so-called SCSI or ATAPI are omitted.

  The CPU 21 performs various operations such as four arithmetic operations and comparison operations, and hardware control based on the operation system program and the application programs such as the mailer and content distribution / reception side programs described above. The RAM 22 stores an operation system program, an application program, and the like read from a storage medium such as a CD-ROM or CD-R mounted in the hard disk 28 or the CD-ROM drive 29, and these are controlled by the CPU 21. Performed originally.

  The ROM 23 stores a so-called BIOS that manages input / output to / from a hard disk or the like in cooperation with the operation system. The LAN adapter 24 communicates with the outside through a network in cooperation with an operation system communication program controlled by the CPU. The video adapter 25 generates an image signal to be output to the display device, and the keyboard 26 and the mouse 27 are used for inputting an instruction to the information processing device.

  The hard disk 28 stores an operation system, the above-described application program, an encryption key database (transmission side terminal), and a received content table (reception side terminal).

  The CD-ROM drive 29 is used for installing a storage medium such as a CD-ROM, CD-R, or CD-R / W and installing an application program on the hard disk 28.

  Needless to say, a CD-R, CD-R / W drive, MO drive, DVD + -R drive, or the like may be used instead of the CD-ROM drive.

  The communication line is typically realized by one of the Internet, LAN, WAN, telephone line, dedicated digital line, ATM, frame relay line, communication satellite line, cable TV line, data broadcasting radio line, or a combination thereof. What is necessary is just to be able to transmit and receive data.

  Here, terms used in the following description will be described. “Specific content” means the content body that is distributed and decrypted this time.

  “Reference content” means content that has been distributed before and that incorporates key information for decrypting specific content.

  “Distribution content” means a file that is actually transmitted. The distribution content includes (1) encrypted specific content, (2) reference information (information for specifying reference content and its key), and (3) key information (for decrypting another content to be transmitted later). It consists of three parts (keys for future use).

  "Distribution" refers to digital transmission of content by means of electromagnetic transmission, light or electrical transmission (wireless or wired), media (DVDs, CD-Rs and other optical disks, DLTs and other tapes, USB memory and compact. This includes a case where the medium is physically moved by storing in a memory card such as various memory cards such as a flash (registered trademark) which can record almost digital signals. Electrical transmission includes, but is not limited to, transmission by email, messaging software, file sharing software, and transfer software using FTP protocol.

  “Receiving” means reading digital signals of content stored on a medium into a computer by means of reading (various drives such as DVD-ROM drives, memory slots, etc.) in addition to receiving electromagnetic waves, light or electrical signals. Means.

  3 is a flowchart of the content distribution side program and mailer of the distribution side terminal. Steps S301 to S304 are executed by the content distribution side program in cooperation with the mailer under the control of the CPU 21, and step S305 is executed by the mailer. It is executed under the control of the CPU 21.

  In S301, when a predetermined button of the mailer (for example, an “encrypted transmission” button that is displayed on the main screen of the mailer when the content distribution program is installed as a plug-in) is pressed, the specific content to be encrypted A dialog for selecting is displayed, and the selected content is stored in the work area of the RAM 22.

In step S302, a dialog for selecting a title and text and selecting a destination mail address group or mail address is displayed. Based on the input title, the selected mail address, and the system date, header information and text information (e-mail) are displayed. Are stored in the work area of the RAM 22. Note that step S302 may be executed by a mailer. An example of the header information is shown in FIG.

  In FIG. 10, “send salary details” is set as the title, “salary details March” is set as the attached data name (content name for distribution), “sender“ personnel section ”is set, and“ general affairs group ”is set as the receiver.

  In step S303, the specific content is encrypted using the key selected based on the designation of the key selection condition. Details of the encryption will be described with reference to the flowchart of FIG.

  In step S304, a distribution content is created from the encrypted specific content, key ID, key information, and reference information. Details of the distribution content creation will be described with reference to the flowchart of FIG.

  In step S305, the mailer creates mail transmission data (including encoding by MIME) based on the header information, body information, and attached file distribution content stored in the work area of the RAM 22, and the specified distribution destination. Send to address.

  Next, FIG. 4 is a detailed flowchart of the encryption process (S303) of the specific content in FIG. 3, and steps S401 to S407 are executed under the control of the CPU 21 of the distribution side terminal.

  In S401, the selection condition for the key to be encrypted is read from the selection condition table to the work area of the RAM. The selection condition table is, for example, a table for storing selection conditions registered by starting a condition input program (stored in the hard disk) (not shown) in the content creation / distribution apparatus in advance on a screen as shown in FIG. It is. As setting range information, (1) for each part of the name of the content (for example, normalized expression such as salary details *), (2) for each mail address group of the distribution destination, (3) for each mail address of the distribution destination, (4) It is possible to set a combination of a part of the content name and each mail address group of the distribution destination, and (5) a combination of a part of the content name and each mail address of the distribution destination, and the order of priority is (5)> ( 4)> (3)> (2)> (1), but can be changed.

The key selection condition includes the above-described setting range information, the number of keys, and the distribution period of the reference content (for example, the latest two weeks, the same month, the same month 3, the same month 6). For example, in the case of (4), specific conditions are as shown in FIG.
Setting range information Content name: Salary details *
Email Address Group: General Affairs (Group)
Number of keys: 3
Distribution period: 1M (Last January).

  In the mail address group, a group ID may be used instead of the name.

  In step S402, a key is randomly selected from the encryption key database. The encryption key database includes an encryption key table (key ID and key information), a distribution history table (distribution date, distribution destination email address group or distribution destination email address, content name, key ID) shown in FIG. All the mail address lists for each mail address group name and update history information (mail address group name, added / deleted category, added / deleted mail address, update date) of the destination mail address group are stored. When the delivery destination email address group name is designated, the delivery destination email address may be blank, and when the delivery destination email address is designated, the delivery destination email address group name may be blank.

  In step S403, the distribution history table is referenced based on the distribution destination mail address group or distribution destination mail address of the header information stored in the work area of the RAM, and the key of the key that the recipient of the current content is to select. Determine if it matches the recipient.

  That is, it is determined whether the key to be selected is included in the reference content transmitted in advance to the recipient of the current content. If it is determined that they match, the process proceeds to step S404. If it is determined that they do not match, the process returns to step S402.

  In step S404, the distribution history table is referred to based on the distribution period stored in the work area of the RAM, and it is determined whether or not the key to be selected this time is created and transmitted to the recipient.

  If it is determined that the key is created within the distribution period, the key information of the key is stored in the work area of the RAM as the key to be used this time, and the process proceeds to step S405. If it is determined that it has not been created within the distribution period, the process returns to step S402.

  In step S405, it is determined whether the name of the reference content including the key matches the content name of the selection condition or a part thereof. If they match, the process proceeds to step S406. If not, the process returns to step S402.

  In step S406, it is determined whether the number of keys of the key information used this time stored in the work area of the RAM has reached the number of selection conditions (for example, 3). If not, the process returns to S402. If it has reached, the process proceeds to step S407.

  In step S407, the distribution history table is searched using the key ID of the selected key as a key, the content name including the key and the transmission date are stored in the RAM work area, and the distribution is performed as shown in FIG. The reference information included in the content (a set of reference content names, distribution dates, and key IDs is stored for a specified number) is created to create distribution content, and the process proceeds to step S408.

  In step S408, the specific content is encrypted using the currently selected key information stored in the work area of the RAM. For example, a known algorithm such as Twofish, Rjindael, GOST 28147-89 is used as the encryption algorithm.

  Next, FIG. 5 is a flowchart showing detailed processing for creating distribution content (step S304 in FIG. 3).

  In step S501, for example, a random number sequence is selected based on the system date and time, and a new key for embedding a distribution content to be attached to one or a plurality of distribution contents based on a random value of the random number sequence. Create information.

  In step S502, a new unique key ID corresponding to the key information created in step S501 is assigned with reference to the key database.

  In S503, the key ID corresponding to the key information in S501 (S502), the content name of the specific content in which the key ID and the key information are incorporated, the receiver information (the receiving side mail address group name or the receiving party mail address), the transmission date Data for key database registration including date is created and stored in the work area of the RAM.

  In step S504, the key database registration data created in step S503 is registered in the key database.

  In step S505, a distribution content is created based on the specific content encrypted in step S303, the reference information created in step S406, and the key database registration data created in step S503, and the process ends.

  The key database registration data may include a pair of dummy key IDs and corresponding key information in addition to a set of one or more key IDs and corresponding key information.

  Next, FIG. 6 is a flowchart showing the processing of the mailer of the receiving side terminal and the content receiving side program (consisting of a received content management unit and a decryption processing unit). A received content table is stored in the hard disk of the receiving terminal, and the received content table includes a transmission date, a received content name, and a sender mail address.

  In step S601, the mailer receives the e-mail attached with the distribution content and stores it in the received mail folder in the hard disk.

  In step S602, received content information to be registered in the received content table is created based on the header information of the mail in the received mail folder and the attached content name for distribution, and stored in the work area of the RAM.

  In step S603, the created received content information is registered in the received content table.

  In step S604, the encrypted specific content included in the distribution content is decrypted. Details of the decoding process will be described with reference to the flowchart of FIG.

  In step S701, the received content is searched from the received content table using n pieces of information (reference content name, transmission date, key ID) included in the reference information in the received distribution content as a key, and the corresponding reception is received. N key IDs are extracted from the content (reference content) and stored in the work area of the RAM.

  In step S702, it is determined whether n key IDs extracted from the reference content match n key IDs in the distribution content. If they match, the process proceeds to step S703. If they do not match any of them, an error message and the name of the reference content are displayed.

  In step S703, n key information is extracted from the reference content based on the n key IDs extracted from the reference content, and stored in the work area of the RAM.

  In step S704, the specific content encrypted using the extracted key information is decrypted.

  According to the above embodiment, the key information is read and decrypted from the other content that has been received and accumulated based on the reference information included in the content. become unable.

[Second Embodiment]
In the first embodiment described above, the reference information includes the name of the reference content, the key ID, and the transmission date. However, it is assumed that the reference content includes only one valid key that is not a dummy key. It is good also as a structure which includes the name of a content for reference, and a transmission date not including.

[Third Embodiment]
In the first embodiment, the reference content is retrieved from the received content table using the content name and the distribution date among the reference information (content name, key ID, transmission date), but the distribution content received in the received content table. Is also stored, and in step S701, the received content table is searched using the transmission date and the key ID as keys.

  As described above, each embodiment has been described. However, the present invention can take an embodiment as a system, apparatus, method, program, recording medium, or the like, and specifically includes a plurality of devices. The present invention may be applied to a system including a single device.

  The configuration of a data processing program that can be read by the information processing apparatus according to the present invention will be described below with reference to the memory map shown in FIG.

  FIG. 13 is a diagram illustrating a memory map of a recording medium (storage medium) that stores various data processing programs that can be read by the information processing apparatus according to the present invention.

  Although not specifically shown, information for managing a program group stored in the recording medium, for example, version information, creator, etc. is also stored, and information depending on the OS on the program reading side, for example, a program is identified and displayed. Icons may also be stored.

  Further, data depending on various programs is also managed in the directory. In addition, when a program or data to be installed is compressed, a program to be decompressed may be stored.

  The functions shown in FIGS. 3 and 6 in this embodiment may be performed by a host computer by a program installed from the outside. In this case, the present invention is applied even when an information group including a program is supplied to the output device from a recording medium such as a CD-ROM, a flash memory, or an FD, or from an external recording medium via a network. Is.

  As described above, a recording medium in which a program code of software for realizing the functions of the above-described embodiments is recorded is supplied to the system or apparatus, and the computer (or CPU or MPU) of the system or apparatus is stored in the recording medium. It goes without saying that the object of the present invention can also be achieved by reading and executing the program code.

  In this case, the program code itself read from the recording medium realizes the novel function of the present invention, and the recording medium storing the program code constitutes the present invention.

  The above-described program only needs to be able to realize the functions of the above-described embodiments by a computer, and the form includes forms such as object code, a program executed by an interpreter, and script data supplied to the OS. But you can.

  As a recording medium for supplying the program code, for example, RAM, NV-RAM, flexible disk, magnetic disk, optical disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD (DVD-ROM, DVD-RAM, DVD-RW, DVD + RW), magnetic tape, nonvolatile memory card, ROM, EEPROM, silicon disk, or the like may be used as long as the program can be stored.

  Furthermore, the program may be supplied by downloading from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) or the like running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the recording medium is written in a memory provided in a function expansion board inserted in the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

  Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or apparatus. In this case, by reading a recording medium storing a program represented by software for achieving the present invention into the system or apparatus, the system or apparatus can enjoy the effects of the present invention.

  Furthermore, by downloading and reading out a program represented by software for achieving the present invention from a server, database, etc. on a network using a communication program, the system or apparatus can enjoy the effects of the present invention. It becomes.

  The present invention can also be applied to encryption and decryption processing of various contents including confidential documents via electronic mail, file transfer programs, and message software.

It is a figure which shows the system configuration | structure in embodiment. It is a figure which shows the hardware constitutions of the content preparation distribution apparatus and content decoding apparatus in embodiment. It is a flowchart which shows the process of the content transmission side program performed with the content preparation distribution apparatus in embodiment. It is a flowchart which shows the detail of the specific content encryption process (step S303) in embodiment. It is a flowchart which shows the detail of the content creation process for distribution in embodiment (step S304). It is a flowchart which shows the process of the content receiving side program performed with the content decoding apparatus in embodiment. It is a flowchart which shows the detail of the decoding process (step S604) of the specific content in embodiment. It is a figure which shows the layout of the encryption key database in an embodiment, and a data example. It is a figure which shows the layout and data example of the reference information in embodiment. It is a figure which shows the header of the transmission document in embodiment. It is a figure which shows the layout and data example of the selection condition table of the content preparation distribution apparatus in embodiment. It is a figure which shows the screen at the time of key condition table registration in embodiment. It is a figure explaining the memory map of the recording medium (storage medium) which stores the various data processing program which can be read by the content creation distribution apparatus and content decoding apparatus in embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Content distribution apparatus 15 Content decoding apparatus 19 Communication line 20 System bus 21 CPU
22 RAM
23 keyboard 24 mouse 25 hard disk 29 storage medium drive

Claims (8)

Key information generating means for generating key information for decrypting the specific content by being incorporated in the reference content;
Management information storage means for storing information for specifying the reference content and management information including the key information;
First encryption means for encrypting specific content based on key information in the management information;
Reference information for identifying one or a plurality of reference contents necessary for decrypting the specific contents and generating reference information for reading one or a plurality of key information included in the reference contents Generating means;
Content creation means for creating distribution content based on the encrypted specific content, the reference information, and another key information for decrypting the content for later distribution distributed after the specific content;
A content creation / distribution device comprising distribution means for distributing the distribution content to other devices;
A receiving means for receiving the specific content via a communication line, a storage means for storing the specific content, and a previously received one stored in the storage means based on reference information incorporated in the fixed content Or a content decryption device comprising: a content decryption device including a first decryption unit that reads one or a plurality of key information included in a plurality of other content and decrypts the specific content. system. The content creation / distribution device further includes a second encryption unit that encrypts at least one of the decryption key information and the reference information,
The content distribution system according to claim 1, wherein the content decryption apparatus further includes a second decryption unit configured to decrypt at least one of the decryption key information and the reference information.   The reference information includes first specifying information for specifying one or more other reference contents, and second specifying information for specifying one or more keys included in the reference contents. The content distribution system according to claim 1, wherein: The reference information further includes one or more dummy information composed of a set of the first specific information and the second specific information,
The first decoding means determines whether a set of the first specific information and the second specific information in the reference information is dummy information, and the first specific information determined not to be dummy information; The content distribution system according to claim 3, wherein decryption is executed using the second specific information.   The content distribution system according to claim 1, wherein the key information generation unit generates individual or plural types of key information according to the plurality of content decrypting devices. A control program for a content creation / distribution device connected to a content decryption device via a communication line,
Key information generating means for generating key information for decrypting other content by incorporating the content creation / distribution device into the content;
Management information storage means for storing management information including information for specifying the content and the key information;
First encryption means for encrypting specific content based on the key information of the management information;
Based on the key information used when encrypted by the other first encryption means, one or more previously distributed reference contents necessary for decrypting the specific contents are identified. Reference information generating means for generating reference information for reading one or more pieces of key information included in the reference content;
A control program for functioning as content creating means for creating distribution content based on the encrypted specific content, the reference information, and another key information for decrypting the content distributed after the specific content . A content decryption device control program connected to a content creation / distribution device via a communication line,
The content decryption device;
Based on reference information incorporated in the fixed content, storage means for storing the specific content received via the communication line, and one or more other previously received contents stored in the storage means A control program for functioning as a first decryption unit that reads out one or a plurality of pieces of key information included and decrypts the specific content.   A storage medium storing the control program according to claim 6 or 7 so as to be readable by a computer.

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