JP2009110534A - Temporary reproducing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To share contents respectively possessed by a plurality of users who have tokens of encrypted contents. <P>SOLUTION: A content reproducing system is constructed to have a means for requesting reproduction for requesting reproduction of the encrypted content and having the tokens, and a means for temporary reproduction for reproducing the encrypted content by responding to the request of reproducing the content. The means for temporary reproduction transmits a request for transmission of the token in a format which attaches a content identifier and digital signature, and the means for requesting reproduction temporarily returns the token to the means for temporary reproduction only when authentication of the digital signature succeeds. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a content reproduction technique using digital content, and in particular, content such as music and video that content creators have a predetermined usage right including copyright can be safely (ie, copyrighted). The present invention relates to a content reproduction technology that can be used.

  More particularly, the present invention relates to a content reproduction technology that protects copyright by permitting the use of encrypted content using a token, and in particular, content between a plurality of users who own tokens of encrypted content. The present invention relates to a content reproduction technology that can share the content.

  The copyright is a relative exclusive monopoly right that can use the work, and is included in one of so-called intangible property rights. The “literary work” as used herein refers to a creative expression of thought or feeling, and belongs to the range of literary arts, academics, art, or music. Copyright is protected by, for example, the copyright laws of each country and international treaties such as the Berne Convention and the Universal Copyright Convention.

  The use of copyrights is rarely performed by the copyright holders themselves, and it is general to grant permission for use of copyrights by others with a certain price. For example, a record company that owns copyrights related to music content such as music may request a royalty fee according to the number of times the content is used from a broadcasting station or content distributor that uses or broadcasts the music content. it can.

  In recent years, information processing and information and communication technologies have made great progress, and internationalization has made remarkable progress in cultural and economic fields. Under such a social environment, the situation concerning copyright is changing every moment. The history of copyright protection is said to have originated from the invention of printing technology in the middle of the 15th century, but now all data and contents can be digitized and handled on a computer system. As the form of distribution and sale of copyrighted works has changed, the reproduction of copyrighted works has become easier. Therefore, from the viewpoint of information technology, it is considered necessary to support the legitimate use of copyrighted works or to eliminate illegal use to expand copyright protection.

  For example, the distribution and sale of music content has traditionally been performed exclusively by displaying physical media such as record boards and CDs (Compact Discs) at stores through physical distribution channels and sales channels. . However, recently, there is a distribution / sales form in which music content as digital data is provided on a website such as a WWW (World Wide Web) server, that is, distributed in a public network environment such as the Internet. It is becoming popular. In the latter content distribution / distribution action, the existence of physical media and physical distribution / sales channels are completely omitted. That is, almost no physical constraints are imposed, and each general user can freely acquire content.

  For example, a street terminal for selling digital contents can be installed in a public place such as a convenience store, and a user can download or purchase music contents there. Alternatively, the user can download music data from his / her home via a telephone line. In addition, with the expansion of the mobile environment, it has become possible to download music content at any place at any time using a mobile phone line.

  Recently, portable information devices called multifunctional portable terminals have appeared. This kind of portable device is equipped with a mobile phone function and Internet access function to download music content, as well as music content playback function and to transfer data and content to other nearby devices It has the inter-device wireless communication function. For the inter-device wireless communication function, a short-range wireless data communication technology such as “Bluetooth (registered trademark)” can be used.

  By the way, in the distribution and sale of music content through the traditional physical media, the act of purchasing a storage medium is almost equivalent to the license for the copyrighted work. On the other hand, in the case of distribution / sales in the form of digital content, duplication is further facilitated. Therefore, it is necessary to suppress or control duplication and unauthorized use of copyrighted works from a technical point of view.

  Copyright protection of music content is realized by using, for example, a kind of license key called “token”. The protection of music content using tokens is generally realized by the following procedure. That is,

(1) Distribute and distribute music content in an encrypted form.
(2) A secret key for encrypted music content is used as a token.
(3) A token is supplied only to a content reproduction device of a legitimate user through a security-guaranteed route.
(4) In the content reproduction apparatus for a legitimate user, a token is stored in a circuit module having tamper resistance, and is used for decrypting encrypted music content. In addition to the token, it is preferable that a program code for reproducing content using the token is executed in the tamper-resistant circuit module.

  As a result, the decryption use of the music content is permitted only during the legitimate use in the reproduction apparatus of the authorized user. Note that tamper resistance means that the circuit package is tightly sealed, and attempting to disassemble the circuit package for internal data decoding etc. will cause damage to the circuit itself and inevitably internal access is prohibited. Means the nature of a simple circuit package.

  In the traditional music content sales form, possession of content media proves that it is a legitimate user. On the other hand, when distributing and selling digital contents, it is proof that the user is a legitimate user, not the contents. In the latter case, for example, as long as the token is held on the multi-function mobile terminal, the music content can be obtained and reproduced via the network at any time. That is, the encrypted music content and the token can be used separately, and it is not necessary to always carry a physical medium. Naturally, it is freed from the inherent problems when dealing with items such as damaged or lost media.

  However, since a token is always required for the reproduction of music content, there are some problems in token management.

  For example, if you want to play music content on two or more devices, traditionally you only have to move and exchange physical media between devices, but if you use encrypted content, you must move tokens between devices. Don't be.

  When free copying of tokens between devices is permitted, it is convenient because it is possible to play back content on both the copy source and copy destination devices, but it is difficult to control unauthorized copying of tokens, and copyright protection for content Is not enough. In addition, when the transfer of tokens between devices is permitted in a form that does not permit copying, copyright protection is assured, but when the devices leave again, there is a problem of misplaced tokens. On the original device that failed to collect the token, even if it has the encrypted music content itself, it cannot be played back. Token misplacement is logically equivalent to media misplacement.

  In addition, when a plurality of users bring tokens and regular playback devices together and enjoy the content playback by concentrating the tokens on a single device, there is a risk that the tokens will be mixed up when each user is dispersed again. Such a token mix is logically equivalent to a media mix.

  Now consider a specific example.

  For example, “Bluetooth (registered trademark)” as a short-range wireless data communication technology has been proposed to be applied to a LAN (Local Area Network) in an automobile (see Non-Patent Document 1). In such a case, it is possible to easily construct a hands-free environment by integrating a portable device carried by each occupant and an in-vehicle audio device using a wireless LAN. In other words, by designating the output target of music content held by each portable device as an in-vehicle audio device, each occupant brings music content that can normally be listened to by one person without a headset into the vehicle, You can share the playback. The portable device referred to here may be the above-described multifunctional portable terminal.

  Even in such a usage form, the in-vehicle audio device that reproduces the music content must have a corresponding token.

  For example, it is convenient because all portable devices can centrally manage the music content held by all passengers in one place by moving the token together with the music content to the in-vehicle audio device. Each occupant can receive a song name list collected by the in-vehicle audio device via the wireless LAN and freely select a song provided by another occupant. In addition, the in-vehicle audio device can have a larger storage capacity than the portable device, which is convenient for intensive storage of many music contents. Furthermore, each passenger can share various audio functions of the in-vehicle audio device. In general, an in-vehicle audio device is more expensive than a multi-function portable terminal, and can provide high sound quality.

  However, in order to ensure the copyright protection for each content, it is necessary to move the token in a form that prohibits unauthorized duplication, unauthorized use, or diversion of the token, and collects it again in each original portable device. It is difficult to realize such token movement / recovery through an intuitive operation.

  Also, when a plurality of users collect tokens, there is a risk of troubles such as misplaced / forgotten tokens, misuse, and loss. Even if a “lost child” token appears, the in-vehicle audio device cannot voluntarily erase or discard the token in order to retain the content usage right of the original owner.

  On the other hand, as a method of sharing music content in the car without moving the token, the data reproduced on the original portable device is transmitted in real time to the in-vehicle audio device using the wireless LAN, It is conceivable to output sound. According to this method, since the token remains on the original portable device, the operation, ie token management, is greatly simplified.

  However, since all the music contents are not concentrated on the in-vehicle audio device, the other occupants cannot freely select the music contents possessed by a certain occupant. Further, during the content reproduction, since the portable device is in a full operation state, the power consumption increases (generally, the portable device is battery-driven, and the increase in the power consumption is serious). In addition, logically, line out output from a portable device and the vehicle audio device is merely used as an audio amplifier, so it is possible to enjoy various audio functions of the vehicle audio device. Can not.

Nikkei Electronics 1999.12.13 (n.759) pp. 139-150

  The object of the present invention is to allow content creators to use content having a predetermined usage right such as copyrights safely (that is, while protecting the copyright) such as music and video. Is to provide a content reproduction technology.

  A further object of the present invention is to provide an excellent content reproduction technique capable of protecting copyright by permitting use of encrypted content using a token.

  It is a further object of the present invention to provide an excellent content reproduction technique that allows a plurality of users who own tokens of encrypted content to share the content they own.

The present invention has been made in consideration of the above problems, and a first aspect thereof is a content reproduction system for reproducing encrypted content that can be decrypted with a token,
Playback request means for holding the token and requesting playback of the encrypted content;
In response to the content reproduction request, the reproduction request unit requests the token to be sent, and a temporary reproduction unit reproduces the encrypted content using the token;
It is the content reproduction system characterized by comprising.

  Here, the reproduction request unit and the temporary reproduction unit may be connectable by short-range wireless data communication. An example of such short-range wireless data communication is “Bluetooth (registered trademark)”.

  Further, the reproduction request unit may hold one or more encrypted contents and tokens for each encrypted content, and may transfer the held encrypted contents to the temporary reproduction unit. The temporary reproduction means may include means for accumulating encrypted content received from one or more reproduction request means.

  The temporary reproduction means may transmit a token sending request in a format attached with an identifier of a content requested for reproduction and a digital signature to the reproduction request means. In such a case, the reproduction request unit returns the token to the temporary reproduction unit only when the digital signature authentication procedure is successful, and in other cases, the token is not returned to prevent spoofing. be able to.

  The temporary reproduction means may have a public key cryptosystem public key and secret key. The digital signature may include the public key of the temporary reproduction means. In such a case, the reproduction request means can return the token safely by encrypting the token with the public key of the temporary reproduction means.

  By implementing the playback requesting means and / or the temporary playback means on a tamper-resistant circuit package, it is possible to completely eliminate fraudulent acts such as token / content analysis / leakage / tampering by unauthorized / bad users. Thus, the security level can be further improved.

  In a use environment where the reproduction request unit and the temporary reproduction unit can be connected by short-range wireless data communication, a plurality of the reproduction request units may exist in an area that can be communicated by the short-range wireless data communication. . In such a case, it is efficient if the temporary reproduction means transmits a token sending request all at once.

The second aspect of the present invention includes a reproduction requesting device that holds a token and requests reproduction of encrypted content, and a temporary reproduction device that reproduces encrypted content in response to the content reproduction request. A content playback method for playing back encrypted content that can be decrypted with a token on a configured system,
(A) the reproduction requesting device transmits a content reproduction request with a content identifier attached thereto;
(B) the temporary playback device transmits a request for sending a token in a format attached with an identifier and a digital signature of the content requested to be played back;
(C) the reproduction requesting device returns a token to the temporary reproduction device only when the digital signature authentication procedure is successful;
(D) the temporary playback device playing back the content requested to be played back using the received token;
A content reproduction method comprising:

  Here, the reproduction requesting device and the temporary reproduction device may be connectable by short-range wireless data communication. An example of such short-range wireless data communication is “Bluetooth (registered trademark)”.

Further, the reproduction requesting apparatus has one or more encrypted contents and a token for each encrypted content,
(A) 'the playback requesting device forwards the encrypted content to the temporary playback device in advance;
(A) "the temporary playback device storing encrypted content;
You may comprise.

  The temporary playback device may have a public key cryptosystem public key and secret key. Further, the public key of the temporary playback device can be included in the digital signature transmitted in the step (b). In such a case, in the step (c), the playback requesting device can return the token safely by encrypting the token with the public key of the temporary playback device.

  By mounting the playback request device and / or the temporary playback device on a tamper-resistant circuit package, it is possible to completely eliminate fraudulent acts such as token / content analysis / leakage / tampering by unauthorized / bad users. Thus, the security level can be further improved.

  In a usage environment where the playback requesting device and the temporary playback device can be connected by short-range wireless data communication, a plurality of playback requesting devices may exist in an area that can be communicated by the short-range wireless data communication. . In such a case, in the step (b), it is efficient if the temporary playback device broadcasts a token sending request.

A third aspect of the present invention is a playback requesting device that requests playback of encrypted content that can be decrypted with a token.
Token holding means for holding a token;
Content storage means for storing encrypted content;
Interface means for exchanging data with external devices;
Control means for controlling the operation of the apparatus;
A reproduction requesting device characterized by comprising:

  In the reproduction requesting apparatus according to the third aspect of the present invention, when the control means succeeds in the authentication procedure related to the digital signature in response to receiving the token sending request with the digital signature via the interface means. By returning the token only to the terminal, spoofing by an external device can be suitably eliminated.

  Further, when the public signature of the token sending request source is included in the digital signature, the control means encrypts the token using the public key to secure the token to the request source. Can reply to.

The fourth aspect of the present invention is a temporary playback device for temporarily playing back encrypted content that can be decrypted with a token,
A signature holding means for holding a digital signature;
A secret key holding means for holding its own secret key;
Content storage means for storing encrypted content;
Interface means for exchanging data with external devices;
Content playback means for playing back plain-text content;
Control means for controlling the operation of the apparatus;
A temporary playback device characterized by comprising:

  In the temporary playback device according to the fourth aspect of the present invention, the control means requests to send a token corresponding to the requested content in response to receiving the content playback request via the interface means. In order to do this, a token sending request with a digital signature can be sent. The token sending request destination can authenticate the temporary playback device using this digital signature, and can appropriately eliminate impersonation.

  Further, the control means can cause the content to be played back using the token in response to receiving the token reply to the token sending request.

  The temporary playback device may further include a token holding unit that holds the token only temporarily.

  The temporary token holding here means that the token is not stored for a long period of time, and the token is discarded in addition to discarding the token when the playback request device is taken out of the range where short-range wireless data communication is possible. This includes not copying or transferring to external devices without permission. In short, a token that is a proof of an authorized user is stored only within the scope of the copyright license (or within the allowable range of business conventions). It means to do.

  The content reproduction system according to the present invention comprises reproduction request means and temporary reproduction means. For example, the reproduction request unit is implemented as a portable device carried by each user, and the temporary reproduction unit is implemented as an audio device that can share a reproduction function between users. Therefore, a one-to-one, many-to-one, or many-to-many relationship is formed between the reproduction request unit and the temporary reproduction unit. More preferably, the temporary reproduction means has a content reproduction function that is more functional than the reproduction request means.

  Between the reproduction request unit and the temporary reproduction unit, for example, mutual connection is realized by using short-range wireless data communication such as “Bluetooth (registered trademark)”, and packets can be exchanged.

  Each reproduction request unit normally has an encrypted content and a token corresponding thereto, and only the encrypted content is transferred to the temporary reproduction unit in advance.

  When the reproduction request unit issues a content reproduction request to the temporary reproduction unit, the temporary reproduction unit requests the reproduction request unit to send a token necessary for decrypting the content. The token request preferably includes an identifier of the content requested to be reproduced and a digital signature of the temporary reproduction means. Further, when there are a plurality of reproduction request means, the temporary reproduction means may simultaneously send a token transmission request.

  When receiving the token sending request, the reproduction request unit authenticates the temporary reproduction unit based on the digital signature. Then, the token is returned only when the authentication is completed successfully, and when the authentication fails, the token is not returned to prevent unauthorized use of the token. Further, since the token is highly confidential information, it is preferable that the token is encrypted and sent with the public key of the temporary reproduction means.

  The temporary reproduction means that receives the token can decrypt the encrypted content and reproduce it. That is, the reproduction request means that originally owns the encrypted content can safely execute the content reproduction in the temporary reproduction means having a high-functional reproduction capability, instead of performing the content reproduction by itself.

  According to the present invention, content creators can use content having a predetermined usage right such as copyrights safely (that is, while protecting copyrights) such as music and video. Content reproduction technology can be provided.

  Further, according to the present invention, it is possible to provide an excellent content reproduction technique capable of performing copyright protection by permitting the use of encrypted content using a token.

  Furthermore, according to the present invention, it is possible to provide an excellent content reproduction technique that enables content to be shared among a plurality of users who own tokens of encrypted content.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

  In this specification, as a specific embodiment of the present invention, a plurality of users who normally own the token with the encrypted content are installed in an automobile equipped with an in-vehicle audio device. Let us take a specific example of a local inter-device environment in which each device is interconnected by a transmission line such as a wireless LAN. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows a hardware configuration of a portable device 10 used for carrying out the present invention. An example of a portable device is a so-called “multi-function mobile terminal”, which not only downloads music content with a mobile phone function and Internet access function, but also a music content playback function, and more It has an inter-device wireless communication function for transferring data and content to other devices.

  As shown in the figure, in addition to a central control unit 11 that comprehensively controls the operation inside the device, the portable device 10 includes an RF transmission / reception unit 12 for transmitting and receiving radio waves, and content for storing music content. The storage unit 13, the local memory 14 for the central control unit 11, the playback unit 15 for playing back music content and outputting it as audio data, and an in-vehicle audio device 50 (described later) are close to each other. It is comprised with the interface part 16 for mutually connecting by means, such as distance radio | wireless data communication.

  In order for the portable device 10 to obtain encrypted music content and a token as a proper license for the encrypted content, for example, it is connected to an access point of a predetermined content provider via a mobile phone line or the like, and RF transmission / reception is performed. Received by the unit 12. The encrypted music content is stored in the content storage unit 13 and the token is stored in the local memory 14.

  The local memory 14 includes a functional part for storing program codes for operation control of the device 10 in a nonvolatile manner and a functional part for temporarily or volatilely writing work data of the central control unit 11 such as tokens. Composed. Since part of the program code and work data used in the present embodiment is highly confidential, it is preferable that the central control unit 11 and the local memory 14 are configured by a tamper-resistant LSI (Large Scale Integration) chip. .

  In order to reproduce the music content on the portable device 10, the central control unit 11 reads out the desired encrypted music content from the content storage unit 13 and takes out the corresponding token from the local memory 14, Is used to decrypt the music content, and the playback unit 15 outputs the sound. In the content reproduction, the content reception and the reproduction operation may be performed in real time without storing the content in the content storage unit 13.

  The portable device 10 requires a playback unit 15 including an audio amplifier and a speaker in order to play back music content in a stand-alone state. However, when the content playback function on the in-vehicle audio device 50 side is exclusively used, the playback unit 15 is not necessary.

  In addition, the music content once stored on the portable device 10 can be transferred to an external device such as the in-vehicle audio device 50 via the interface unit 16 and reproduced externally. However, details of the procedure will be described later.

  Further, FIG. 2 schematically illustrates another embodiment 10-2 of the portable device provided for the implementation of the present invention.

  As shown in the figure, the portable device 10-2 includes a central control unit 11 that comprehensively controls the operation inside the device, a media reading unit 17 for reading data from a medium carrying music content, Short-range wireless data communication between the local memory 14 for the central control unit 11, the playback unit 15 for playing back music content and outputting it as audio data, and an in-vehicle audio device 50 (described later) And an interface unit 16 for mutual connection.

  In order for the portable device 10-2 to obtain the encrypted music content, a desired medium may be loaded into the media reading unit 17. In addition, the token as a valid license for the content can be obtained through the same or different distribution channel as the media, and can be input into the device 10-2 via a console not shown in FIG. it can. The token is stored in the local memory 14.

  The local memory 14 has a functional part for storing program code for operation control of the device 10-2 in a nonvolatile manner, and a functional part for temporarily or volatilely writing work data of the central control unit 11 such as a token. It consists of. Since part of the program code and work data used in this embodiment is highly confidential, it is preferable that the central control unit 11 and the local memory 14 are configured by tamper-resistant LSI chips.

  In order to reproduce the music content on the portable device 10-2, the central control unit 11 reads out the desired encrypted music content from the loaded media by the media reading unit 17, and the corresponding token is stored locally. The music content is extracted from the memory 14, decrypted using the token, and output by the playback unit 15 as audio.

  The portable device 10-2 needs a playback unit 15 including an audio amplifier and a speaker in order to play back music content in a stand-alone state. However, when the content playback function on the in-vehicle audio device 50 side is exclusively used, the playback unit 15 is not necessary.

  Also, music content once stored on the portable device 10-2 can be transferred to an external device such as the in-vehicle audio device 50 via the interface unit 16 and reproduced externally. However, details of the procedure will be described later.

  FIG. 3 schematically shows a hardware configuration of the in-vehicle audio device 50 used for carrying out the present invention. The in-vehicle audio device 50 can be connected to the portable device 10 described with reference to FIGS. 1 and 2 using, for example, a short-range wireless data communication technology. That is, when each occupant brings the portable device 10 into the vehicle, the in-vehicle audio device 50 communicates with the plurality of portable devices 10 and cooperates with them to provide a highly functional music content playback service. It can be realized (described later).

  As shown in FIG. 3, the in-vehicle audio device 50 reproduces music content in addition to the central control unit 51 that controls the overall operation of the device, in addition to the local memory 54 for the central control unit 51. A playback unit 55 including an audio amplifier and a speaker for external output as audio data, and an interface unit 56 for mutual connection with the portable device 10 (described above) by means such as short-range wireless data communication The content storage unit 53 stores encrypted music content sent from the portable device 10 of each passenger.

  Further, in order to enjoy the reproduction of music content even when the portable device 10 is not installed in the vehicle, the in-vehicle audio device 50 itself includes a media reading unit 57 for reading data from the media carrying the music content. May be.

  When each occupant brings the portable device 10 into the vehicle, each device 10 is dynamically installed in the execution environment provided by the in-vehicle audio device 50 using, for example, a short-range wireless data communication function. Each portable device 10 transfers the encrypted music content to the in-vehicle audio device 50, so that the reproduction operation of all the music contents can be centrally managed in the in-vehicle audio device 50.

  In order to play the encrypted music content on the in-vehicle audio device 50, it is necessary to obtain a corresponding token from the original content owner, that is, the portable device 10 side. However, if the portable device 10 transfers an unlimited number of tokens, the copyright protection regarding the music content is jeopardized. Therefore, in the present embodiment, each portable device 10 permits token transfer only to the in-vehicle audio device 50 that has succeeded in a predetermined authentication procedure described later.

  The indispensable condition of the in-vehicle audio device 50 that succeeds in the authentication procedure is to hold the received token only temporarily, and automatically discard the token when a necessary period of time such as playing music content elapses. To comply with token usage restrictions (ie, to ensure copyright protection for content).

  A digital signature and a private key necessary for the authentication procedure are stored in the local memory 54. The local memory 54 includes a functional part for storing program codes for operation control of the device 50 in a nonvolatile manner, and a functional part for temporarily or volatilely writing work data of the central control unit 51 such as tokens. Composed. Since a part of the program code and work data used in this embodiment is highly confidential, it is preferable that the central control unit 51 and the local memory 54 are constituted by tamper-resistant LSI chips.

  The “secret key” here is a secret key of a public key cryptosystem. The public key encryption method is an encryption method using two types of keys (asymmetric keys) that can be decrypted only with one key when encrypted with one key. By using one key as a private key that only the user knows and using the other key as a public key that is disclosed to a third party, a secret document encrypted with the public key or a digital signature encrypted with the private key can be used (Well-known).

  Next, the processing procedure of the music content reproduction service realized by the cooperative operation of the portable device 10 and the in-vehicle audio device 50 will be described. It should be understood that the reproduction of the music content mentioned here means a temporary or one-time content reproduction by the in-vehicle audio device 50.

  FIG. 4 illustrates a processing procedure of a music content reproduction service realized between the portable device 10 and the in-vehicle audio device 50. However, in the example shown in the figure, the portable device 10 and the in-vehicle audio device 50 are in a one-to-one relationship for the sake of simplicity. Further, in the illustrated example, the portable device 10 functions as a “reproduction requester” that requests the reproduction of music content, and the in-vehicle audio device 50 side temporarily reproduces the content in response to the request. It shall function as a “temporary player”.

  By bringing the portable device 10 into the vehicle on which the in-vehicle audio device 50 according to the present embodiment is mounted, the portable device 10 is connected to the in-vehicle audio device 50 by short-range wireless data communication. An example of short-range wireless data communication is “Bluetooth (registered trademark)”.

  Before issuing the playback request, the portable device 10 transfers the encrypted music content stored therein to the temporary playback device 50 side in advance (T1).

  FIG. 5 shows an example of the data structure of encrypted music content. As shown in the figure, the encrypted music content is composed of a data main body 61 and a header portion 62. The data body is a field for storing music content, and is written in an encrypted state. The other header section 62 includes control information such as a song title, artist name, and content ID (for example, ISRC (International Standard Recording Code)). In order to make control information such as a song name available before the authentication procedure of the temporary playback device 50, it is preferable that the header 62 is in a plaintext state that is not encrypted.

  Upon receiving such encrypted music content, the temporary playback device 50 stores it in the content storage unit 53 as it is (S1).

  Next, on the playback requesting machine 10 side, a playback request is issued to the temporary playback machine 50 side by a console (not shown) provided in the portable device 10 (T2).

  This reproduction request is transmitted by short-range wireless data communication as a “reproduction instruction packet” instructing reproduction of a specific music piece. FIG. 6 illustrates the data structure of the reproduction instruction packet. As shown in the figure, the reproduction instruction packet includes a reproduction command and a content ID corresponding to the music title, and can designate reproduction of a specific music.

  In order to play the encrypted music content, a corresponding token is required. Therefore, when determining that the packet received from the playback requesting device 10 is a playback instruction packet, the temporary playback device 50 generates a token request packet including its own digital signature (S2), The data is transmitted to the reproduction requesting machine 10 side using short-range wireless data communication (T3).

  FIG. 7 illustrates a data structure of the token request packet. As shown in the figure, the token request packet is composed of a token request command, a content ID corresponding to a song title, and a digital signature. The digital signature is composed of the public key of the temporary playback device 50 itself and a specific character string used for authentication processing.

  The token request command and the content ID are in plain text format. On the other hand, since the digital signature is composed of secret data encrypted with the authentication secret key, impersonation by an unauthorized user can be prevented. The digital signature is preferably written in advance in a tamper-resistant circuit chip at the time of manufacturing the temporary playback device, that is, the in-vehicle audio device 50.

  The authentication private key and public key are managed by, for example, the manufacturer of the portable device 10 and / or the in-vehicle audio device 50. Among these, the public key for authentication can be widely used by general third parties including the portable device 10. In order to realize the present invention suitably, it is assumed that the manufacturer and its product are committed to protecting the copyright of the content.

  When receiving the token request packet, the reproduction requester 10 side extracts a digital signature from the packet and authenticates the temporary reproduction device 50 (S11). More specifically, this authentication procedure involves decrypting the digital signature with the authentication public key (described above) to determine whether the specific character string for authentication could be restored in a meaningful form. Done in

  If the authentication procedure is successfully completed, the playback requesting device 10 extracts the token corresponding to the content ID included in the token request packet, and encrypts the copy with the public key of the temporary playback device 10 restored from the digital signature. (S12). Then, a copy of the encrypted token is sent back to the temporary player 50 side using short-range wireless data communication (T4).

  The temporary playback device 50 that has received the copy of the token decrypts it using its own private key and takes out the token (S3). Then, the token is held in a volatile state (S4).

  The volatile state here means that the token is not stored for a long period of time and the token is discarded when the portable device 10 is taken out of the vehicle, and the token is copied or transferred to an external device without permission. In short, it means that a token, which is a proof of a legitimate user, is stored only within the scope of copyright permission (or within an acceptable range for business reasons).

  The temporary playback device 50 extracts the music content requested to be played from the content storage unit 53 and decrypts it using the acquired token (S5). Then, DA (Digital-Analog) conversion is performed to reproduce the sound data (S6), and the sound data is externally output by the reproducing unit 55 including an audio amplifier and a speaker (S7).

  In addition, on each side of the reproduction requesting machine 10 and the temporary reproduction machine 50, it is necessary to perform a safe process that eliminates dangers such as intrusion / decoding / leakage / tampering from the outside in the hatched portions. . Therefore, it is more preferable that the program code corresponding to the hatched area is configured as a non-division process and is mounted on a tamper-resistant circuit device.

  In the above description, for example, the case where the portable device 10 and the in-vehicle audio device 50 are in a one-to-one relationship in a specific automobile is limited. In such a case, as shown in FIG. 8, the user can perform music content transfer, playback instruction, temporary playback authentication, and the like via the console screen of the portable device 10.

  However, in many cases, as a result of several people getting in a single vehicle, a plurality of portable devices 10 coexist and one in-vehicle audio device 50 is shared. In such a case, the portable device 10 and the in-vehicle audio device 50 form a many-to-one relationship instead of one-to-one, and as shown in FIG. Music content is acquired from the portable device 10 or playback requests from a plurality of portable devices 10 are received.

  In the present invention, even when the portable device 10 and the in-vehicle audio device 50 form a many-to-one relationship, the same operation as described above is preferably performed. Refer to the chart shown in FIG. However, it will be explained in detail below. However, it is assumed that transactions between the devices shown in FIG. 10 are performed using short-range wireless data communication in principle.

  First, when each occupant brings his / her portable devices # 1, # 2, # 3... Into the vehicle, the connection with the in-vehicle audio device, that is, the temporary playback device 50 is made by using short-range wireless data communication. Establish.

  In such a state, each of the portable devices # 1, # 2, # 3... Sequentially transfers the encrypted content stored therein to the temporary playback device 50 side.

  As described with reference to FIG. 5, the encrypted music content includes a data main body 61 composed of the encrypted content and a header portion 62 that remains in plain text. Therefore, the temporary playback device 50 side can generate a song name list for the collected music content before performing an authentication procedure for each music content or sending a token (described later).

  Each portable device # 1, # 2, # 3... In the vehicle can request the temporary playback device 50 to send a song name list. In response to this, the temporary playback device 50 returns a song name list in a packet format.

  FIG. 11 shows an example of the data structure of the song name list sending packet. As shown in the figure, the music title list may be a list obtained by cutting out the header portions of each music content according to a predetermined format.

  Each portable device # 1, # 2, # 3... That has received the song name list sending packet can display a song name list for which a playback service is provided in the temporary playback device 50 on the console panel. The user of each portable device can select a desired music piece on the console panel. As a result of the music selection, the portable device issues a playback request to the temporary playback device 50. As shown in FIG. 6, this reproduction request is sent in the form of a reproduction instruction packet with a content ID corresponding to the selected music piece.

  On the other hand, the temporary player 50 side requires a corresponding token in order to play the encrypted music content. Therefore, the temporary playback device 50 generates a token request packet including its own digital signature and broadcasts (broadcasts) it to each of the portable devices # 1, # 2, # 3.

  The data structure of the token request packet is as already described with reference to FIG. That is, the token request packet includes a token request command, a content ID corresponding to a song title, and a digital signature. The digital signature is composed of the public key of the temporary playback device 50 itself and a specific character string used for authentication processing. The token request command and the content ID are in plain text format. On the other hand, since the digital signature is encrypted with the authentication private key, impersonation by an unauthorized user can be prevented.

  FIG. 12 shows a processing procedure executed by each of the portable devices # 1, # 2, # 3... When receiving a token request packet in the form of a flowchart. Hereinafter, description will be given according to this flowchart.

  The portable device 10 first extracts the digital signature from the token request packet, decrypts it with the authentication public key (described above) (step S51), and performs the authentication operation (step S52). In the authentication operation, it is determined whether or not the specific character string for authentication can be restored from the digital signature in a meaningful format.

  If the authentication fails, there is a possibility that the temporary player 50 that requested the token is impersonating, that is, an unauthorized reproducing device, and therefore the entire processing routine is terminated without performing the token sending process.

  On the other hand, when the authentication is successfully completed, the portable device 10 determines whether or not it owns the token corresponding to the content ID specified in the token request packet (in other words, the mobile device 10 itself Whether the user is a legitimate user) or not (step S53).

  If the corresponding token cannot be found, since the user is not a valid user of the content, the entire processing routine is terminated without performing the token sending process.

  On the other hand, if the corresponding token can be found, a copy of the token is encrypted with the public key of the temporary playback device 50 included in the digital signature and returned to the temporary playback device 50 (step S55).

  When receiving a copy of the token, temporary player 50 can decrypt the token with its own private key and obtain a token. As a result, it is possible to reproduce the music content requested to be reproduced.

  Note that in short-range wireless data communication such as “Bluetooth (registered trademark)”, the reach of wireless data is almost the same as the reach of voice such as car stereo. Therefore, when the in-vehicle audio device 50 can recognize the presence of the portable device 10 holding the token by short-range wireless data communication, the token owner himself / herself listens to the music content. Even if content is played back on a playback device other than a portable device, it is considered that there is no problem from the viewpoint of copyright. In such a situation, it is understood that there is no problem in interpreting rights even if a reproduction request is issued from another portable device that is not the token owner.

  According to the music content playback method of the present embodiment, the token or a copy thereof is safely and automatically transferred to the temporary playback device that has received the playback instruction, so that the token is transferred between the portable device 10 and the in-vehicle audio device 50. The trouble of moving can be saved.

  In addition, even when the portable device user sequentially switches the playback device that requests content playback, each temporary playback device holds the token only in a volatile manner and diverts it to other uses without permission. Since it is guaranteed not to do so, token management is simplified.

  The present invention can also be applied to a case where the playback requesting machine and the temporary playback machine form a many-to-many relationship. In this case, it is assumed that the same music content is on a plurality of temporary playback devices. In such a case, to which player the token should be sent should be determined by the user, that is, the authorized owner of the token, and a token transfer procedure is required separately from the music content transfer.

  That is, according to the present invention, it is possible to save the trouble of sequentially repeating the necessary procedure every time the player is changed.

  As with media, as already mentioned, tokens can be misplaced, lost, or misunderstood. For example, if you ride in a number of cars and go to a drive, and an occupant changes cars on the way, to which car the music content was transferred, or in which car the token was left behind, End up.

  In contrast, according to the present invention, a copy of the token is sent to a trusted temporary player that has been authenticated, so the original player does not need to collect the token and leaves the token behind. There is no worry at all.

  The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiments without departing from the gist of the present invention. In other words, the present invention has been disclosed in the form of exemplification, and should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims described at the beginning should be taken into consideration.

It is the functional block diagram which showed typically the hardware constitutions of the portable apparatus 10 provided for implementation of this invention. It is the functional block diagram which showed typically the other form 10-2 of the portable apparatus provided for implementation of this invention. It is the functional block diagram which showed typically the hardware constitutions of the vehicle-mounted audio apparatus 50 provided for implementation of this invention. 4 is a chart showing a processing procedure of a music content reproduction service realized between the portable device 10 and the in-vehicle audio device 50 (provided that the portable device 10 and the in-vehicle audio device 50 have a one-to-one relationship). ). It is the figure which showed the example of the data structure of an encryption music content delivery packet. It is the figure which showed the example of the data structure of a reproduction | regeneration instruction | indication packet. It is the figure which showed the example of the data structure of a token request packet. It is the figure which portrayed the operation procedure using the portable apparatus 10 in a vehicle. It is the figure which portrayed the operation procedure using the portable apparatus 10 in a vehicle. It is the chart which showed the operation | movement procedure of each apparatus in case the portable apparatus 10 and the vehicle-mounted audio apparatus 50 form many-to-one relationship. It is the figure which showed the example of the data structure of a song name list sending packet. It is the flowchart which showed the process sequence which the portable apparatus 10 performs when a token request packet is received.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Portable apparatus 11 ... Central control part 12 ... RF transmission / reception part 13 ... Content storage part 14 ... Memory 15 ... Playback part 16 ... Interface part 17 ... Media reading part 50 ... In-vehicle audio equipment 51 ... Central control part 53 ... Content Storage unit 54 ... Memory 55 ... Playback unit 56 ... Interface unit 57 ... Media reading unit

Claims (5)

A temporary playback device that temporarily plays back encrypted content that can be decrypted with a token,
A signature holding means for holding a digital signature;
A secret key holding means for holding its own secret key;
Content storage means for storing encrypted content;
Interface means for exchanging data with external devices;
Content playback means for playing back plain-text content;
Control means for controlling the operation of the apparatus;
A temporary playback device comprising: The digital signature held by the signature holding means includes at least the public key of the temporary playback device itself and a specific character string for the authentication procedure.
The temporary reproduction apparatus according to claim 1, wherein: In response to receiving the content reproduction request via the interface unit, the control unit transmits a token sending request with a digital signature requesting sending of a token corresponding to the requested content.
The temporary reproduction apparatus according to claim 1, wherein: In response to receiving a token response to the token sending request, the control means causes the content to be reproduced using the token.
The temporary reproduction apparatus according to claim 3. And a token holding means for holding the token only temporarily.
The temporary reproduction apparatus according to claim 1, wherein: