JP4609111B2 - Content transmission system, content transmission method, content holding apparatus, and program thereof - Google Patents

Description

  The present invention relates to a content transmission system, and more particularly, to a content transmission system, a content transmission method, a content holding device, and a program thereof that prevent falsification of content.

  Nowadays, it is natural to download and use various information from a public communication network such as the Internet to a mobile terminal such as a mobile phone. In addition, information such as URLs related to the poster is obtained by placing a mobile terminal such as a mobile phone over an IC tag or IC card embedded in an advertising poster posted at a station, etc. A technique for performing such processing (for example, Patent Document 1) is also in the implementation stage.

  IC tags and IC cards embedded in such posters can perform data communication in a non-contact manner by wireless communication, can maintain the appearance of the poster beautifully, and can reduce maintenance costs. is doing.

  Content is written to the IC tag or IC card using a separate external device. Poster managers use proprietary encryption techniques to protect the data so that its contents are not tampered with. Thus, if content protection is performed for each administrator, the protection program area and cost increase. However, if the protection program is unified and its specifications are released, the security of the content may be impaired.

JP 2001-160105 A

  The present invention has been made in view of the above-mentioned problems of the conventional content protection method, and an object of the present invention is to unify the content protection method and publish its specifications so that an IC tag or an IC card can be obtained. New and improved content transmission system, content transmission method, content holding device, and program capable of improving the user-friendliness and preventing falsification of content by other managers and unauthorized persons despite the disclosure of specifications Is to provide.

  As described above, each administrator who manages the conventional content holding apparatus has independently protected the content. The content is exclusively written from the content writing device to the content holding device using the original encrypted communication.

  The present invention is characterized by reliably preventing falsification of content with a simple restriction of permitting content writing by a write flag without performing such encrypted communication.

  In order to solve the above problems, according to an aspect of the present invention, a content holding device that holds content, a content writing device that writes content to the content holding device, and a content reading device that reads content from the content holding device The content holding apparatus includes: a holding communication unit that communicates a command and content; a content; a write flag indicating “write enabled / disabled” of the content; and the write flag A data storage unit that stores a write password for updating; a password determination unit that determines whether a write password of a command input to the holding communication unit is equal to a write password stored in the data storage unit; and the password Equal in the decision part A flag update unit that updates the write flag in accordance with the command; and stores the content input to the holding communication unit in the data storage unit only when the write flag is “writable” A content writing unit for overwriting; and a content reading unit for reading content stored in the data storage unit regardless of the write flag in response to a content read request. A content transmission system is provided, wherein the content reading apparatus includes a reading communication unit that reads content.

  According to the above configuration, the administrator of the content holding device writes the content in the content holding device using the content writing device. However, since content writing is restricted by the content writing unit, first, the flag updating unit must change the writing flag so that the content can be written. To change the write flag, a write password given to the administrator is required. By interlocking the write password and the write flag, the contents are prevented from being falsified by another administrator or an unauthorized person.

  In addition, the content reading unit of the content holding device is not limited as the content writing unit described above, and the user having the content reading device can read the content freely, and the geographical location of the destination can be determined from the read URL. Further processing such as grasping the position can be performed.

  In order to solve the above-described problem, according to another aspect of the present invention, a holding communication unit that communicates a command and content; a content; a write flag indicating “write enabled / disabled” of the content; and the write A data storage unit for storing a write password for updating the flag; a password determination unit for determining whether the write password of the command input to the holding communication unit is equal to the write password stored in the data storage unit; A flag update unit that updates the write flag in accordance with the command when the password determination unit determines that they are equal; and a content that is input to the holding communication unit only when the write flag is “writable” A content writing unit for storing or overwriting in the data storage unit; Depending on the look-up request, regardless of the write flag, the content reading section reads the content stored in the data storage unit and; content holding device equipped with is provided. The content holding device may be an IC tag or an IC card that can transmit data in contact or non-contact.

  According to this configuration, as described in the content transmission system, the content holding device does not perform encrypted communication with other external devices, and the content can be falsified with a simple restriction that the content writing is permitted by the write flag. It can be surely prevented. The write flag can be updated only by a person having a write password (for example, an administrator of the content holding device). The administrator or the like updates the writing flag to “writable”, writes the content, and then returns the writing flag to “writable” to prevent falsification of the content.

  In the above configuration, the write flag and the write password can be made unreadable to the outside, so that other administrators or unauthorized persons cannot obtain the write password.

  In addition, when the password determination unit determines that the passwords are equal, a password update unit that updates the write password stored in the data storage unit to a new write password according to the command may be further provided.

  The password update unit can change the write password for each administrator. Therefore, the manufacturer of the content holding device can set a common write password at the time of shipment, and each administrator can independently update the write password during operation. In this way, a unique write password can be set for each content holding device. In order to improve security, it is conceivable to update the write password every predetermined period or at the time of content rewriting.

  When a specific command (forced change command) is input, a password forced change unit that forcibly changes the write password stored in the data storage unit to a predetermined initial password may be further provided. Further, the password forcibly changing unit may forcibly change the password to a predetermined initial password only when a master password is input in addition to a specific command (forced change command). The initial password and master password are provided in advance in the content holding device.

  If the write password is leaked for some reason, the content in the content holding device is rewritten by an unauthorized user, and the write password itself is also rewritten. When the write password is changed, an administrator who has only the write password before the update can no longer operate the content holding device.

  Regardless of the illegally changed write password, the password forced change unit forcibly changes the write password to the initial password using, for example, a predetermined master password known only by the content holding device manufacturer. The administrator can set a new write password by using the initial password.

  A program that functions as the content holding device is also provided. In such a program, the computer executes each component of the content holding device. A storage medium storing such a program is also provided. Furthermore, the content writing device and the content reading device are also provided.

  In order to solve the above-described problem, according to another aspect of the present invention, the content holding device receives a content write request from an external device; and a write flag indicating “write enabled / disabled” of the content Determining whether or not “write enabled”; storing or overwriting content input from the external device in the data storage unit only when the write flag is “write enabled”; A content transmission method comprising: a step of transmitting content stored in the data storage unit when there is a content read request from a device or another external device.

  With such a configuration, it is possible to reliably prevent falsification of content with a simple restriction that the content holding device does not perform encrypted communication with other external devices and permits content writing by a write flag.

  Determining whether the write password of the command input from the external device is equal to the write password stored in the data storage; updating the write flag in accordance with the command if the write password is determined to be equal And a step of updating the write password stored in the data storage unit to a new write password according to the command when it is determined that the write password is equal. It is also good.

  Furthermore, when a specific command (forced change command) is input, a step of forcibly changing the write password stored in the data storage unit to a predetermined initial password may be further included. In addition, the step of forcibly changing to the predetermined initial password may be performed only when a master password is input in addition to a specific command (forced change command).

  Communication between the content writing device and content reading device and the content holding device may be performed by wire or wireless, and may be performed by a contact method or a non-contact method.

  Also, the content writing device and the content reading device can be configured as a single device. Further, the contents of the data storage unit of the content holding device may be stored in separate storage devices, and each component of the content holding device may be provided separately in separate devices.

  As described above, according to the present invention, it is possible to improve the usability of the IC tag and the IC card by unifying the content protection method and publishing the specifications, and the conventional encryption communication is not performed. Reduction is also possible.

  In addition, although the specifications are disclosed as described above, the use of the write flag can surely prevent the contents from being tampered with by another administrator or an unauthorized person.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  For example, when trying to obtain URLs and map information related to the contents of advertising posters posted at stations, etc., only acts such as tricking a mobile terminal such as a mobile phone into an IC tag or IC card embedded in the poster With this, information can be downloaded without contact.

  As the non-contact wireless communication as described above, for example, a near field communication (NFC) can be used. Since such NFC has a narrow use range of about 10 cm, it is excellent in security, such as limiting communication partners by hand action.

  Information (contents) related to the advertisement poster is held in an IC tag or an IC card, and is updated by an administrator of the poster. The poster manager uses a unique encryption technology, for example, individual encryption communication, so that the contents are not falsified. In such an operation, IC tag manufacturers are required to have versatility corresponding to various kinds of encrypted communication in IC tags, and an administrator constructs an original encrypted communication and installs an encrypted communication program in the IC tag. You will be forced to increase costs.

  Because of this inconvenience, it is desirable to unify the content writing method and publish its specifications. However, if content writing becomes possible, there will naturally be a person who falsifies the content due to unauthorized access. Therefore, it is not possible to ensure the security of the content simply by unifying the content writing method.

(First embodiment: content transmission system)
In this embodiment, the encryption communication for each administrator is not performed, and a new write flag is provided, and content tampering is reliably prevented with a simple restriction such as permitting content writing by the write flag.

  FIG. 1 is a block diagram showing a schematic configuration of a content transmission system in the present embodiment. The content transmission system includes a content holding device 100 that holds content, a content writing device 110 that writes content to the content holding device 100, and a content reading device 120 that reads content from the content holding device 100.

  The content holding apparatus 100 is installed on a tangible object 130 such as a poster. The tangible object 130 includes public objects such as advertisements, posters, bulletin boards, and signboards, and can be used for the purpose of conveying some information to the user.

  The content writing device 110 and the content reading device 120 are provided separately from the content holding device 100, and are mobile phones, PDAs (Personal Digital Assistants), mobile personal computers, watches, calculators, mice, etc. that can be moved by the user. Is implemented.

  The manager of the tangible object 130 such as a poster, with respect to the IC tag as the content holding device 100 at the time of setting the poster or before that, information related to the contents of the poster (URL, summary information, detailed information, map information, Write the price, date, etc. When the user is interested in the content of the poster, in order to record the content of the poster or to obtain new information, the user brings the portable terminal close to the IC tag of the poster and starts downloading by a simple operation.

  The present embodiment is characterized in that the administrator writes the content in the IC tag. Also, there is no restriction on the user's downloading of the poster content. That is, it can be downloaded freely.

  FIG. 2 is a block diagram illustrating a schematic configuration of the content holding device 100, the content writing device 110, and the content reading device 120 in the present embodiment.

(Content holding device 100)
The content holding device 100 includes a holding communication unit 200, a data storage unit 202, a password determining unit 204, a flag updating unit 206, a content writing unit 208, a content reading unit 210, a password updating unit 212, and a password. And a forced change unit 214.

  The holding communication unit 200 communicates with the content writing device 110 and the content reading device 120 such as commands for writing content and changing the writing password, and the content 230 held by the content holding device 100. Such communication may be performed by wire or wireless, and may be performed by contact or non-contact.

  The data storage unit 202 includes at least a content 230 input from the content writing device 110, a write flag 232 indicating “write enabled / disabled” of the content 230, a write password 234 for updating the write flag, The initial password 236 referred to by the forced change command is stored.

  When there is a content write request from the content writing device 110, the password determination unit 204 determines whether the write password in the write request command input to the holding communication unit is equal to the write password 234 stored in the data storage unit 202. Judge whether.

  When the password determination unit 204 determines that the password update unit 206 is equal to the write password 234 stored in the data storage unit 202, the flag update unit 206 sets the write flag so as to be in the new write flag state indicated in the command. 232 is updated. When the write flag indicated in the above command is the same as the write flag before the update, the write flag may be overwritten or may not be updated. Further, the write flag exclusively indicates at least two values of “write enabled” and “not writeable”, and may be expressed by 1 or 2 or more bits or bytes by a logical code such as 1, 0, for example.

  The content writing unit 208 stores or overwrites the content 230 input to the holding communication unit 200 in the data storage unit 202 only when the write flag 232 is “writable”.

  The administrator of the content holding device 100 uses the content writing device 110 to write the content 230 into the content holding device 100 via the content writing unit 208. The content writing unit 208 restricts content writing in order to prevent content tampering. The administrator first updates the write flag to “write enabled” by the flag update unit 206. In order to update the write flag, a write password 234 assigned to the administrator is required. By interlocking the write password 234 and the write flag 232, falsification of content from other administrators or unauthorized persons is prevented.

  In addition, only the person who knows the write password such as an administrator can update the write flag. Such an administrator or the like updates the write flag to “writable”, writes the content, and then writes the content by a series of processes such as returning the write flag to “writable”.

  The content reading unit 210 reads the content stored in the data storage unit 202 and transmits it to the holding communication unit 200 regardless of the state of the write flag 232 in response to a content reading request from the content reading device.

  The content reading unit 210 is not limited as the content writing unit 208 is, and a user having the content reading device 120 can freely read the content 230, for example, a URL included in the read content 230 Further processing can be performed, such as grasping the geographical location of the destination from

  When the password update unit 212 determines that the password determination unit 204 is equal to the write password 234 stored in the data storage unit 202, the password update unit 212 refers to the new write password indicated in the command, and the data storage unit The write password 234 before update stored in 202 is updated to a new write password.

  The write password 234 stored in the data storage unit 202 is represented by a series of character strings in which numbers and Roman letters are mixed. The password update unit 212 can change the write password 234 for each administrator. Therefore, the manufacturer of the content holding apparatus 100 can set a common write password 234 as an initial value at the time of shipment, and each administrator can freely change the write password 234 during operation. In this way, a unique write password 234 is set for each content holding device 100. In addition, security can be improved by performing processing such as changing the write password 234 every predetermined period or at the time of content rewriting.

  When a specific command (forced change command) and a master password are input, the password forced change unit 214 uses a write password 234 stored in the data storage unit as a predetermined initial password (new write password). Forcibly change to 236.

  In the content transmission system in the present embodiment, it is assumed that the write password 234 leaks for some reason. When the write password 234 is leaked in this way, the content 230 of the content holding device 100 may be rewritten by an unauthorized user, and the write password 234 itself may be rewritten. When the write password 234 is changed, the administrator who has only the write password before the update can no longer restore the altered content of the content holding device 100 or overwrite it again.

  Regardless of the illegally changed write password 234, the forced password change unit 214 forces the write password to the initial password 236 using, for example, a predetermined master password known only by the manufacturer of the content holding device 100. Can be changed. Then, using the forcibly changed initial password 236, the administrator can separately set a new write password.

  A program that functions as the content holding device 100 and a storage medium that stores the program are also provided.

(Content writing device 110)
The content writing device 110 includes a writing storage unit 250 and a writing communication unit 252.

  The write storage unit 250 stores the content 260 and the write password 262 necessary for writing the content.

  The write communication unit 252 communicates a write request command including the content 260 and the write password 262 to the content holding device 100.

  The content holding device 100 and the content writing device 110 described above can reliably prevent falsification of content with simple restrictions such as permitting content writing by a write flag without performing encrypted communication.

(Content reading device 120)
The content reading device 120 includes a reading communication unit 270 and a reading storage unit 272.

  The reading communication unit 270 reads the content 230 from the content holding device 100.

  The reading storage unit 272 stores the content 230 read from the reading communication unit 270. The content stored in this way is further processed by the user of the content reading device.

(Second embodiment: content transmission method)
In the first embodiment, the detailed configuration of each device of the content transmission system has been described. In the present embodiment, a specific processing flow in the content transmission system will be described in detail.

  The content transmission method roughly includes content writing, content reading, update of a write flag, update of a write password, and forced change of the write password. In the following, description will be given separately for such processing.

(Content writing)
FIG. 3 is a flowchart showing a flow of processing related to content writing in the content transmission method.

  First, the content holding device 100 receives a content write request from an external device such as the content writing device 110 (S300). Upon receiving such a write request, the content writing unit 208 of the content holding device 100 refers to the write flag 232 of the data storage unit 202 and determines whether the write flag 232 is “write enabled” (S302).

  If the write flag 232 is “Writable”, the content 230 input from the external device is stored or overwritten in the data storage unit 202 (S304), and the external device requested to write is written. For example, an ACK signal or the like indicates that the content writing has been completed (S306). If the write flag 232 is “not writable” in the write flag determination step (S302), the content 230 is not written and the external device is informed that writing is impossible. No response is made (S308).

  The content cannot be written unless the write flag 232 is “write enabled”. Therefore, actually, the write flag is temporarily updated to “writable” by updating the write flag as described below, and after writing is completed, it is further returned to “writable”.

(Reading content)
FIG. 4 is a flowchart showing a flow of processing related to reading of content in the content transmission method.

  When a content reading request is received from an external device such as the content reading device 120 (S400), the content 230 stored in the data storage unit 202 is transmitted (S402). Here, reading of the content is not restricted, but using the flag or the like like the write flag 232, the content is only given to a specific user, for example, a user who has a license for downloading the content. It can also be provided.

(Update write flag)
FIG. 5 is a flowchart showing a flow of processing relating to update of the write flag in the content transmission method.

  First, the content holding device 100 receives a write flag update request command from an external device such as the content writing device 110 (S500), and the write password of the update request command is equal to the write password 234 stored in the data storage unit 202. It is judged (S502).

  Here, when it is determined that the write password in the request command is equal to the write password 234 of the data storage unit 202, the write flag 232 is updated according to the command (S504), and an external request for update of the write flag is made. The update of the write flag 232 is notified to the device (S506). If it is determined in the write password determination step (S502) that the write passwords 234 are not equal, the update of the write flag 232 is not performed and the external device is informed that the update of the write flag is impossible. Or no response at all (S508).

  FIG. 6 is an explanatory diagram showing an example of a write flag update request command in the update of the write flag. The write flag update request command includes a header 600, a command code 602, an updated write flag 604, a write password 606, and a footer 608.

  The header 600, together with the footer 608, indicates the head and tail of the write flag update request command and represents one unit of the command.

  The command code 602 indicates that the command sandwiched between the header 600 and the footer 608 is a code indicating a write flag update request.

  The updated write flag 604 indicates the state of the write flag desired to be updated, and “write is possible” is written immediately before the content is written, and “write is impossible” is written after the content is written.

  The write password 606 is a password for operating the content holding device 100 included in the content writing device 110. In order to write the content in the content holding device 100, the write password held in the content holding device 100 and the write password 606 must be equal.

(Update write password)
FIG. 7 is a flowchart showing a flow of processing related to update of the write password in the content transmission method.

  First, the content holding device 100 receives a write password update request command from an external device such as the content writing device 110 (S700), and the write password of the update request command is equal to the write password 234 stored in the data storage unit 202. It is judged (S702).

  If it is determined that the write password in the request command is equal to the write password 234 of the data storage unit 202, the write password 234 is updated to a new write password according to the command (S704), and the write password is updated. The update of the write password 234 is notified to the external device that has made the request (S706). If it is determined in the write password determination step (S702) that the write passwords 234 are not equal, the write password 234 is not updated and the external device is notified that the write password cannot be updated. Or no response at all (S708).

  FIG. 8 is an explanatory diagram showing an example of a write password update request command in the update of the write password. The write password update request command includes a header 800, a command code 802, a current write password 804, a new write password 806, and a footer 808.

  The header, command code, and footer already described in the write flag update request command in FIG.

  The current write password 804 is a password that should be the same as the write password 804 held in the current content holding device 100. Updating to a new password is allowed only when such write passwords are equal.

  The new write password 806 is a new password to be updated.

(Force change of write password)
FIG. 9 is a flowchart showing a flow of processing related to the forced change of the write password in the content transmission method.

  First, the content holding device 100 receives a write password forced change command and a master password from an external device such as the content writing device 110 (S900), and compares the master password with the master password of the content legal device 100 (S902). If the master passwords are equal, the write password 234 stored in the data storage unit 202 is forcibly changed to a predetermined initial password 236 regardless of the write password 234 at the time when the command is input (S904). ).

  Subsequently, it notifies the external device that has transmitted the forced change password command that the change of the initial password write password 234 has been completed (S906). If it is determined in the master password determining step (S902) that the master passwords are not equal, the writing password 234 is not changed, and it is notified to the external device that the writing password cannot be changed. Alternatively, no response is made (S908).

  The write password forced change command includes a header, a command code indicating forced change, and a footer in the command examples shown in FIGS. Since this forced change command is preferably held only by the manufacturer of the content holding device, the administrator may be provided by an initialization tool or the like that becomes a black box.

  With the content transmission method as described above, it is possible to disclose the specifications without relying on encrypted communication, and the usability of IC tags and IC cards can be improved. Although the specifications are disclosed, it is possible to reliably prevent content alteration by other managers or unauthorized persons by the write flag.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the content transmission system described above, one administrator (business operator) is described, but a plurality of administrators may be included in one content holding device (for example, an IC tag or an IC card). Of course, it is possible to display a plurality of advertisements on a tangible object such as a poster.

  Note that the steps in the content transmission method of the present specification do not necessarily have to be processed in time series in the order described in the flowchart, but are executed in parallel or individually (for example, parallel processing or object-based processing). Processing).

  The present invention relates to a content transmission system, and more specifically, can be applied to a content transmission system, a content transmission method, a content holding device, and a program thereof that prevent falsification of content.

1 is a block diagram illustrating a schematic configuration of a content transmission system according to a first embodiment. 1 is a block diagram illustrating a schematic configuration of a content holding device, a content writing device, and a content reading device according to a first embodiment. It is the flowchart which showed the flow of the process regarding content writing. It is the flowchart which showed the flow of the process regarding reading of a content. It is the flowchart which showed the flow of the process regarding update of a write flag. It is explanatory drawing which shows an example of the write flag update request command in the update of a write flag. It is the flowchart which showed the flow of the process regarding update of a write password. It is explanatory drawing which shows an example of the write password update request command in the update of a write password. It is the flowchart which showed the flow of the process regarding forced change of a write password.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Content holding | maintenance apparatus 110 Content writing apparatus 120 Content reading apparatus 200 Holding | maintenance communication part 202 Data storage part 204 Password judgment part 206 Flag update part 208 Content writing part 210 Content reading part 212 Password update part 214 Password forced change part 252 Write communication part 270 Reading communication part

Claims (12)

A holding communication unit for communicating commands and contents;
A data storage unit for storing content, a write flag indicating whether the content can be written, and a write password for updating the write flag;
A password determination unit for determining whether a write password of a command input to the holding communication unit is equal to a write password stored in the data storage unit;
A flag update unit that updates the write flag in accordance with the command when the password determination unit determines that they are equal;
A content writing unit that stores or overwrites the content input to the holding communication unit in the data storage unit only when the write flag is writable;
A content reading unit that reads content stored in the data storage unit regardless of the state of the write flag in response to a content read request;
A content holding device.   The password update unit for updating the write password stored in the data storage unit to a new write password according to the command when the password determination unit determines that they are equal. The content holding device according to 1.   When a specific command (forced change command) is input, a password forced change unit that forcibly changes the write password stored in the data storage unit to a predetermined initial password is further provided. The content holding device according to claim 2.   The password forcibly changing unit forcibly changes to a predetermined initial password only when a master password is input in addition to a specific command (forced change command). The content holding device described.   The content holding apparatus according to claim 1, wherein the content holding apparatus is an IC tag. Computer
A holding communication unit for communicating commands and contents;
A data storage unit for storing content, a write flag indicating whether the content can be written, and a write password for updating the write flag;
A password determination unit for determining whether a write password of a command input to the holding communication unit is equal to a write password stored in the data storage unit;
A flag update unit that updates the write flag in accordance with the command when the password determination unit determines that they are equal;
A content writing unit that stores or overwrites the content input to the holding communication unit in the data storage unit only when the write flag is writable;
A content reading unit that reads content stored in the data storage unit regardless of the state of the write flag in response to a content read request;
Program to make it function. Content holding device
Receiving a content write request from an external device;
Determining whether a write flag indicating whether content can be written is enabled;
A step write flag is to be stored or overwritten only when it is determined that that has become writable, the content input from the external device to the data storage unit in said step of determining;
Transmitting content stored in the data storage unit when there is a content read request from the external device or another external device , regardless of the state of the write flag ;
A content transmission method comprising: Determining whether a write password of a command input from the external device is equal to a write password stored in the data storage unit;
Updating the write flag according to the command if the write passwords are determined to be equal;
The content transmission method according to claim 7, further comprising:   The method of claim 8, further comprising: updating the write password stored in the data storage unit according to the command to a new write password when it is determined that the write password is equal. Content transmission method.   The method further comprises a step of forcibly changing the write password stored in the data storage unit to a predetermined initial password when a specific command (forced change command) is input. 10. The content transmission method according to 9.   The step of forcibly changing to the predetermined initial password is performed only when a master password is input in addition to a specific command (forced change command). Content transmission method. A content transmission system comprising a content holding device that holds content, a content writing device that writes content to the content holding device, and a content reading device that reads content from the content holding device:
The content holding device includes:
A holding communication unit for communicating commands and contents;
A data storage unit for storing content, a write flag indicating whether the content can be written, and a write password for updating the write flag;
A password determination unit for determining whether a write password of a command input to the holding communication unit is equal to a write password stored in the data storage unit;
A flag update unit that updates the write flag in accordance with the command when the password determination unit determines that they are equal;
A content writing unit that stores or overwrites the content input to the holding communication unit in the data storage unit only when the write flag is writable;
A content reading unit that reads content stored in the data storage unit regardless of the state of the write flag in response to a content read request;
With
The content writing device includes:
A write communication unit for communicating the command including the write password with the content;
With
The content reading device includes:
Reading communication unit that reads content;
A content transmission system comprising:

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