JP2006317997A - Content delivery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a content delivery system, capable of delivering a desired content from a server to a designated reproduction terminal using a cellular phone through a simple operation. <P>SOLUTION: The server 1 is accessed using the cellular phone 3 to purchase a license necessary for reproduction of the desired content. For reproducing the content, a session identifier is acquired from the server 1 using the cellular phone 3. The session identifier is transmitted from the cellular phone 3 to the reproduction terminal 2 through infrared communication. The reproduction terminal 2 transmits the session identifier to the server 1 and requests delivery of the content. The desired content is delivered to the reproduction terminal 2 in a streaming system, and reproduced in the reproduction terminal 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a content distribution system, and more particularly to a content distribution system that distributes desired content from a server to a specified client using a portable information terminal.

  Currently, a service is provided in which music content is distributed to a mobile phone and can be viewed on the mobile phone.

  However, since the communication speed of the mobile phone is still slow, the content size is reduced and the music reproduction quality is sacrificed. In addition, it is difficult to adopt a streaming method in which contents are reproduced in order while being delivered little by little. For this reason, generally, a download method is adopted in which the entire content is temporarily stored in a mobile phone and then played back. Furthermore, as long as playback is performed by a mobile phone, there is a certain limit to improving playback quality.

  Japanese Patent Laying-Open No. 2003-92639 (Patent Document 1) discloses a method of distributing content from a server to a specified in-vehicle terminal using a mobile phone. According to this method, an in-vehicle terminal ID (identifier) assigned in advance to a designated in-vehicle terminal is transmitted from the mobile phone to the server, and a purchase reservation number (hereinafter referred to as “one-time”) associated with the in-vehicle terminal ID in response to this is transmitted. Password ") from the server to the mobile phone. When the one-time password obtained by the user is manually input to the designated in-vehicle terminal, the in-vehicle terminal ID and the one-time password are transmitted from the in-vehicle terminal to the server. Authentication is performed with the in-vehicle terminal ID and the one-time password, and when the authentication is successful, the content list to be downloaded is transmitted from the server to the designated in-vehicle terminal. Then, the content in the content list is downloaded from the server to the designated in-vehicle terminal.

In this method, the vehicle-mounted terminal ID is used as essential authentication information, and a one-time password is used as arbitrary authentication information to further enhance security (see paragraphs 0008 and 0043 of the publication). Therefore, the in-vehicle terminal ID must be manually input to the mobile phone, which is troublesome. The downloaded content can be copied, and no measures for copyright protection are taken.
JP 2003-92639 A JP 2003-124922 A JP 2002-132713 A JP 2001-297263 A JP 2003-259335 A JP 2004-265139 A

  An object of the present invention is to provide a content distribution system capable of distributing desired content from a server to a specified client using a portable information terminal with a simple operation.

Means for Solving the Problems and Effects of the Invention

  A content distribution system according to the present invention includes a server, a client that can access the server, and a portable information terminal that can access the server. The server includes a content data database for storing content data in association with the content identifier, means for issuing a session identifier corresponding to a desired content in response to a request from the portable information terminal, and the issued session identifier. Means for registering in the session management database in association with the content identifier of the desired content, referring to the session management database in response to a request from the client, identifying the content identifier corresponding to the session identifier transmitted from the client, and Content transmitting means for reading content data corresponding to the content identifier from the content data database and transmitting it to the client. The client receives the session identifier issued by the server, transmits the received session identifier to the server, and requests the server to transmit the content data of the desired content, and transmits from the server And reproducing means for reproducing the content data. The portable information terminal includes means for requesting the server to issue a session identifier corresponding to desired content in response to a user operation. Here, the portable information terminal includes a mobile phone, a PHS (Personal Handy phone System), a PDA (Personal Digital Assistance), and other mobile terminals. The session identifier may be transmitted from the server to the portable information terminal, further transmitted from the portable information terminal to the client, or may be transmitted from the server to the client.

  In this content distribution system, the mobile information terminal requests the server to issue a session identifier in response to a user operation, and the session identifier is issued accordingly. This session identifier is transmitted to the client, and further transmitted from the client to the server. When desired content is requested from the client to the server, content data corresponding to the session identifier is transmitted from the server to the client accordingly. The client reproduces music and / or video based on the content data. Therefore, desired content can be distributed from a server to a specified client using a portable information terminal with a simple operation.

  Preferably, the server further includes means for deleting the session identifier from the session management database after transmitting the content data.

  In this case, the used session identifier cannot be reused.

  More preferably, the server further includes means for encrypting the issued session identifier with a public key assigned to the client. The client further includes means for decrypting the received session identifier with a private key paired with the public key.

  In this case, even if the session identifier is stolen, music and video cannot be reproduced using the session identifier. Therefore, since an unauthorized user who has not received a license has used the session identifier first, a situation in which an authorized user who has received a license cannot use the session identifier does not occur.

  Preferably, the server further includes means for encrypting the common key with a public key assigned to the client, and means for encrypting content data to be transmitted to the client with the common key. The client further decrypts the encrypted common key transmitted from the server with a secret key paired with the public key, and decrypts the encrypted content data transmitted from the server with the decrypted common key. Means for decoding.

  In this case, even if the content data is stolen, music and video cannot be played back by other than the designated client.

  Preferably, the server further refers to the license management database for storing the content identifier in association with the user identifier, the license management database, and specifies one or more content identifiers corresponding to one user identifier, Means for transmitting a list of contents corresponding to the content identifier to the portable information terminal. The portable information terminal further includes means for displaying a list of contents transmitted from the server and means for selecting desired contents from the displayed list of contents in accordance with a user operation.

  In this case, the user can easily reproduce music and video simply by checking the reproducible content in a list and selecting the desired content.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[First Embodiment]
[overall structure]
Referring to FIG. 1, the content distribution system according to the first embodiment of the present invention includes a server 1, a plurality of playback terminals 2, and a plurality of mobile phones 3. Although a PDA (Personal Digital Assistance) may be used instead of the mobile phone 3, an example using the mobile phone 3 will be described here.

  The server 1 stores a large number of music contents and their metadata. Each playback terminal 2 accesses the server 1 via the Internet 4, functions as a client to the server 1, and can play back music content distributed from the server 1 by a streaming method. Each mobile phone 3 accesses the server 1 via the mobile phone carrier 5 and the Internet 4 to purchase music contents, browse a list of purchased music contents (hereinafter referred to as “content list”), It is possible to instruct the playback terminal to play back desired music content by infrared communication.

[Server configuration]
Referring to FIG. 2, the server 1 includes a CPU (Central Processing Unit) 11, a memory 12, a network communication unit 13, a content data database (DB) 14, a content key DB 15, a content metadata DB 16, A license management DB 17 and a session management DB 18 are provided.

  The memory 12 includes a hard disk in addition to a semiconductor memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and stores a program (to be described in detail later) for causing the server 1 to execute predetermined steps. . The network communication unit 13 connects the server 1 to the Internet 4 and transmits / receives data between the playback terminal 2 and the mobile phone 3.

  The content data DB 14 stores a lot of music content data (hereinafter referred to as “content data”) in association with the content identifier CID. The content identifier CID is assigned in advance for each music content in order to identify the music content.

As shown in Table 1, the content key DB 15 stores a common key K2 in association with the content identifier CID. The common key K2 is a secret key used for encrypting and decrypting content data using a common key encryption method.

As shown in Table 2, the content metadata DB 16 stores metadata of music content in association with the content identifier CID, specifically, song name (title), artist name, playback time, album name, jacket image, and the like. is doing.

As shown in Table 3, in the license management DB 17, one or more content identifiers CID are registered in association with the user identifier UID to specify the music content purchased by the user. The license management DB 17 also registers a license type, the number of times of viewing, and the like in association with the content identifier CID. The license type includes “unlimited” that can be viewed repeatedly as many times as possible, and “restricted number of times” in which the number of times of viewing is limited. In the case of “number limit”, the limit number is also registered. The number of viewing times is the number of times that the user has viewed the music content.

As shown in Table 4, a public key K1P, an expiration date, and a content identifier CID are registered in the session management DB 18 in association with the session identifier SID. The session identifier SID is issued by the server 1 in response to a request from the mobile phone 3, and details thereof will be described later. The public key is a key used for encrypting the session identifier SID and the common key using a public key cryptosystem, and is assigned to each playback terminal 2 in advance. A secret key K1S paired with the public key K1P is also assigned in advance for each playback terminal 2. The expiration date is the final date when the session identifier SID is treated as valid.

[Configuration of playback terminal]
With reference to FIG. 3, the playback terminal 2 includes a CPU 21, a memory 22, a network communication unit 23, an infrared light receiving unit 24, and a playback unit 25.

  The memory 22 includes a hard disk in addition to a semiconductor memory, and stores a program (detailed later) for causing the playback terminal (computer) 2 to execute predetermined steps, the secret key K1S, and the like. The network communication unit 23 connects the playback terminal 2 to the Internet 4 to access the server 1 according to the TCP / IP protocol or the like, and exchanges data with the server 1. The infrared light receiving unit 24 receives infrared light transmitted from the mobile phone 3 and receives data contained therein. The reproduction unit 25 reproduces music based on the content data. The user can view the reproduced music.

  As the playback terminal 2, for example, a network-compatible audio device, a music box installed in a game hall or a restaurant, a communication karaoke device, or a dedicated device having only functions necessary for the present invention can be used.

[Configuration of mobile phone]
Referring to FIG. 4, the mobile phone 3 is a general-purpose product that is widely spread, and includes a CPU 31, a memory 32, a display 33, an input unit 34, a telephone communication unit 35, a network communication unit 36, and infrared light emission. Part 37.

  The memory 32 includes a hard disk in addition to the semiconductor memory, and stores a program (detailed later) for causing the mobile phone (computer) 3 to execute predetermined steps. The input unit 34 receives a key input by a user operation. The telephone communication unit 35 connects the mobile phone 3 to the mobile phone carrier 5 to enable a normal call. The network communication unit 36 connects the mobile phone 3 to the Internet 4 via the mobile phone carrier 5 to access the server 1, and exchanges data with the server 1. The infrared light emitting unit 37 may issue an infrared ray from a normal remote controller, or may emit an infrared ray on which data is placed according to an IrDA (Infrared Data Association) standard.

[Operation]
The operation of the content distribution system is as follows.

[Content purchase procedure]
First, the procedure for purchasing music content will be described.

  5 and 6, the mobile phone 3 accesses the server 1, requests a search category page (S301), and the server 1 receives this (S101). In response to this request, the server 1 returns a search category page to the mobile phone 3 (S102), and the mobile phone 3 receives this (S202). Then, as shown in FIG. 7A, the mobile phone 3 displays a search category selection screen that displays a list of search categories (S203).

  If the user selects “select by artist name” from the displayed search categories, the mobile phone 3 accepts this input (S304) and requests the server 1 for a list of artists (S305). The server 1 receives this (S103). The server 1 refers to the content metadata DB 16 in response to this request, and returns a list of artists to the mobile phone 3 (S104), and the mobile phone 3 receives this (S306). Then, as shown in FIG. 7B, the mobile phone 3 displays an artist selection screen displaying a list of artist names (S307).

  If the user selects “artist name # 1” from the displayed artist names, the mobile phone 3 accepts this input (S308) and requests the server 1 for a list of album names of the artist. Then (S309), the server 1 receives this (S105). In response to this request, the server 1 refers to the content metadata DB 16 and returns a list of album names of the artist to the mobile phone 3 together with the jacket image (S106), and the mobile phone 3 receives this (S310). . Then, as shown in FIG. 7C, the mobile phone 3 displays an album selection screen displaying a list of album names of the artist together with the jacket image (S311).

  If the user selects “album name # 1-1” from the displayed album names, the mobile phone 3 accepts this input (S312), and a list of song names recorded in the album is displayed. (Content list) is requested from the server 1 (S313), and the server 1 receives it (S107). In response to this request, the server 1 refers to the content metadata DB 16 and returns a list of song names recorded in the album to the mobile phone 3 (S108), and the mobile phone 3 receives this (S314). Then, as shown in FIG. 7D, the mobile phone 3 displays a content selection screen displaying a list of song names (titles) recorded in the album (S315). On the content selection screen, a “view” button 6 and a “purchase” button 7 are also displayed in association with the song name.

  If the user selects the “Purchase” button corresponding to “Title # 1” from the displayed song titles, the mobile phone 3 accepts this (S316), as shown in FIG. Then, a purchase confirmation screen for confirming the user's intention to purchase the title is displayed (S317). A “Yes” button 8 and a “No” button 9 are also displayed on the purchase confirmation screen.

  If the user selects the “Yes” button, the mobile phone 3 receives an input of the purchase intention (S318), transmits a purchase notification of the title to the server 1 (S319), and the server 1 receives this. (S109). In response to this notification, the server 1 refers to the content metadata DB 16, identifies the content identifier CID of the title, and registers the content identifier CID in the license management DB 17 in association with the user identifier UID of the user (S110). .

  Although not shown, the mobile phone 3 accepts input of a desired license type and a desired number of times in the case of a license with a limited number of times and transmits them to the server 1 in accordance with a user operation. The server 1 receives these and registers them in the license management DB 17. When a new content identifier CID is registered, the server 1 sets its viewing count to zero.

  After the license registration, the server 1 transmits a purchase completion notification to the mobile phone 3, and the mobile phone 3 receives it (S320). Then, the cellular phone 3 displays the purchase procedure completion notification screen shown in FIG. 7F (S321).

[Content playback procedure]
Next, a procedure for playing purchased music content will be described.

  With reference to FIGS. 8 to 10, the mobile phone 3 accesses the server 1, requests a search category page (S331), and the server 1 receives this (S121). In response to this request, the server 1 returns a search category page to the mobile phone 3 (S122), and the mobile phone 3 receives this (S332). Then, the cellular phone 3 displays the search category selection screen shown in FIG. 11A (S333). This operation is the same as steps S301 to S303, S101, and S102.

  When the user selects “purchased content list” from the displayed search categories, the mobile phone 3 accepts this input (S334), requests the server 1 for a list of purchased content (S335), The server 1 receives this (S123). In response to this request, the server 1 refers to the license management DB 17, returns a list of purchased contents to the mobile phone 3 (S124), and the mobile phone 3 receives this (S336). Then, as shown in FIG. 11B, the mobile phone 3 displays a content selection screen that displays a list of purchased content (S337). On the content selection screen, a “play” button 10 is also displayed in association with the song title (title).

  Next, if the user selects the “play” button 10 corresponding to “title # 1” from the displayed music titles, the cellular phone 3 accepts this input (S338).

  Further, the user designates the reproduction terminal 2 to reproduce the title (content), and inputs the public key K1P assigned in advance to the designated reproduction terminal 2 by operating the input unit 34 of the mobile phone 3. . In response to this operation, the mobile phone 3 receives an input of the public key K1P (S339), and stores the input public key K1P in the memory 32 (S340). If the public key K1P is stored, it is not necessary to re-enter the same public key K1P each time the designated playback terminal 2 is repeatedly used.

  The mobile phone 3 transmits the content identifier CID of the title # 1 and the public key K1P to the server 1 in order to request the server 1 to issue a session identifier SID necessary for reproducing the content (title # 1) (S341). ), The server 1 receives this (S125).

  The server 1 randomly issues a session identifier SID in response to this request (S126), and registers the received public key K1P and content identifier CID in the session management DB 18 in association with the issued session identifier SID (S127). . The server 1 further sets an expiration date of the session identifier SID and registers it in the session management DB 18 (S128). The expiration date is set to about 10 seconds to 1 minute, for example. If the expiration date is set so short, it is difficult to steal and use the session identifier SID within a short period of time, so that the security becomes high.

  Subsequently, the server 1 uses the public key K1P to encrypt the session identifier SID and generate an encrypted session identifier K1P (SID) (S129). The server 1 returns the generated encrypted session identifier K1P (SID) to the mobile phone 3 (S130), and the mobile phone 3 receives this (S342). The mobile phone 3 stores the received encrypted session identifier K1P (SID) in the memory 32 (S343).

  Next, when the user presses a predetermined playback button while pointing the infrared light emitting unit 37 of the mobile phone 3 toward the infrared light receiving unit 24 of the designated playback terminal 2, the mobile phone 3 displays the encrypted session identifier K1P (SID) as the playback terminal. 2 (S344), and the playback terminal 2 receives this (S201).

  The playback terminal 2 uses the secret key K1S stored in the memory 32 to decrypt the encrypted session identifier K1P (SID) and reproduce the original session identifier SID (S202). The playback terminal 2 transmits a session identifier SID to the server 1 in order to request streaming delivery of content data to the server 1 (S203), and the server 1 receives this (S131). At this time, a unique value (client identifier) such as an IP address, a MAC (Media Access Control) address or a device number for identifying the playback terminal 2 is also transmitted from the playback terminal 2 to the server 1 (S203). . This IP address is a client identifier for identifying the playback terminal 2, and the server 1 specifies the playback terminal 2 on the Internet 4 based on this IP address, and returns the requested content data.

  In response to the streaming delivery request from the playback terminal 2, the server 1 refers to the session management DB 18, reads the content identifier CID corresponding to the received session identifier SID, confirms the expiration date of the session identifier SID, It is determined whether or not the session identifier SID is valid (S132).

  The server 1 further refers to the license management DB 17 to determine whether the license corresponding to the read content identifier CID is the unlimited type or the number limit type among the one or more content identifiers corresponding to the user identifier UID of the user. It discriminate | determines (S133). In the case of the number limit type, the server 1 checks the limit number and determines whether or not the number of viewing times has reached the limit number (S134).

  The server 1 transmits a message indicating the confirmation result of the expiration date and the limit number to the reproduction terminal 2 (S135), and the reproduction terminal 2 receives the message (S204). After the notification of the message, the server 1 increments the number of views (S136).

  If the session identifier SID is invalid or the number of viewing times has reached the limit number (NG in S205), the playback terminal 2 fails to play back, and the process ends (S206). On the other hand, when the session identifier SID is valid and the license is an unlimited type (OK in S205), or when the session identifier SID is valid and the license is a limited number of times and the number of viewing times has not reached the limited number (S205). The process proceeds to the next step S207.

  After incrementing the number of viewing times (S136), the server 1 reads the public key K1P corresponding to the session identifier SID from the session management DB 18, reads the common key K2 corresponding to the content identifier CID from the content key DB 15, and further reads the content from the content data DB 14 The content data D corresponding to the identifier CID is read out. The server 1 uses the read public key K1P and encrypts the read common key K2 to generate an encrypted common key K1P (K2) (S137). The server 1 also uses the read common key K2 to encrypt the read content data D to generate encrypted content data K2 (D) (S138). The content data D may be encrypted in advance instead of being encrypted every time it is requested. Since the content data D is distributed by the streaming method, the content data D is divided into a plurality of packets, and each packet is encrypted.

  Subsequently, the server 1 transmits the encrypted common key K1P (K2) and the encrypted content data K2 (D) to the playback terminal 2 (S139), and the playback terminal 2 receives them (S207).

  After transmitting the content data D, the server 1 deletes the session identifier SID and corresponding information from the session management DB 18 (S140).

  On the other hand, the playback terminal 2 uses its own secret key K1S, decrypts the received encrypted common key K2 to reproduce the original common key K2 (S208), and further uses the common key K2 for encryption. The content data K2 (D) is decrypted to reproduce the original content data D (S209). Then, the reproduction terminal 2 reproduces music based on the content data D (S210).

  As described above, according to the first embodiment of the present invention, the user can purchase a license for viewing desired content using the mobile phone 3 and reproduce the content on the designated reproduction terminal 2. it can. Therefore, the content for which a user has purchased a license can be viewed not only on the user's own playback terminal 2, but also on a friend's playback terminal 2, the playback terminal 2 installed in a game hall or restaurant, and the like.

  In addition, when the content is downloaded to the mobile phone and played back, the memory capacity is small, so the number of playable content is extremely limited. In the present embodiment, the content is played back by the streaming terminal 2 Therefore, the number of contents that can be reproduced is not particularly limited. In addition, since the playback terminal 2 such as a network compatible audio device is used instead of the cellular phone, the content can be played back with high sound quality.

  In addition, since the content data is encrypted and distributed, the content cannot be reproduced except by a designated reproduction terminal even if the content data is stolen.

  In addition, since the used session identifier is deleted after the content distribution, the used session identifier cannot be reused.

  In addition, since the session identifier is also transmitted after being encrypted, it cannot be used even if an unauthorized user who has not purchased a license steals the session identifier. Therefore, a situation in which the session identifier is deleted before the licensed authorized user uses the session identifier does not occur.

[Second Embodiment]
In the first embodiment, the user needs to manually input the public key K1P of the playback terminal 2 to the mobile phone 3, but the following may be performed to save this trouble.

  For example, as shown in FIG. 12, the playback terminal 2 and the mobile phone 3 may be connected by a communication cable 20 to perform bidirectional wired communication. In this case as well, the session identifier SID is transmitted from the mobile phone 3 to the playback terminal 2 as described above, but the public key K1P is transmitted from the playback terminal 2 to the mobile phone 3 via the communication cable 20. Specifically, when the mobile phone 3 requests the playback terminal 2 to transmit the public key K1P via the communication cable 20, the playback terminal 2 sends the public key K1P to the mobile phone via the communication cable 20 in response to the request. 3, the playback terminal 2 accepts the input of this public key. Therefore, the user does not need to manually input the public key K1P.

[Third Embodiment]
Further, as shown in FIG. 13, the playback terminal 2 and the mobile phone 3 are connected by short-range wireless communication such as IrDA, Bluetooth (registered trademark), wireless LAN (Local Area Network), etc. May be performed. Also in this case, as described above, the session identifier SID is transmitted from the mobile phone 3 to the reproduction terminal 2, and the public key K1P is transmitted from the reproduction terminal 2 to the mobile phone 3 by short-range wireless communication.

  Although not shown, the public key K1P may be moved from the playback terminal 2 to the mobile phone 3 using a removable storage medium such as a memory card.

[Fourth Embodiment]
Further, in the above embodiment, the mobile phone 3 acquires the issued session identifier SID by transmitting the public key K1P to the server 1, but as shown in FIG. The client identifier CLID of the reproduction terminal 2 may be transmitted to the server 1 instead of the public key K1P, and the issued session identifier SID may be transmitted from the server 1 to the reproduction terminal 2 by polling.

Specifically, in the fourth embodiment, the server 1 further includes a public key DB shown in Table 5 below.

  In the public key DB, a public key K1P, an issue date, and a validity flag are registered in association with the client identifier CLID. Each record is added every time the playback terminal 2 is produced. The client identifier CLID is a unique value assigned every time the playback terminal 2 is produced. The client identifier CLID may be a serial number, but a random value is desirable for security. When the user manually inputs the client identifier CLID into the mobile phone 3, the client identifier CLID may be displayed on the display of the playback terminal 2, but a sticker or the like indicating the client identifier CLID is displayed on the playback terminal 2. You may make it stick. Further, the mobile phone 3 may acquire the client identifier CLID from the playback terminal 2 by a communication cable or near field communication.

  The issue date is a date when the client identifier CLID and the public key K1P are newly registered. The validity flag is invalidated when an illegality is detected in the playback terminal 2, thereby stopping distribution to the playback terminal 2.

Further, as shown in Table 6 below, the client identifier CLID is also registered in the session management DB in association with the session identifier SID.

  In the fourth embodiment, as shown in FIG. 15, the mobile phone 3 receives an input of a client identifier CLID in accordance with a user operation (S351), and stores the input client identifier CLID (S352). . In order to request the server 1 to issue the session identifier SID, the mobile phone 3 transmits the content identifier CID and the client identifier CLID to the server 1 (S353), and the server 1 receives them (S125).

  The server 1 issues a session identifier SID and adds a new record to the session management DB shown in Table 6 (S216). The server 1 refers to the public key DB shown in Table 5 and extracts the public key K1P corresponding to the received client identifier CLID (S141). Then, the server 1 registers the issued session identifier SID, the extracted public key K1P, the received content identifier CID, and the client identifier CLID in the session management DB (S142).

  On the other hand, the playback terminal 2 performs polling at a predetermined cycle, and acquires the session identifier SID addressed to itself from the server 1. Specifically, the playback terminal 2 inquires of the server 1 whether or not a session identifier SID addressed to itself is issued at a predetermined cycle (S211). On the other hand, the server 1 searches the session management DB shown in Table 6 to determine whether or not there is a client identifier CLID of the playback terminal 2, that is, whether or not there is a session identifier SID issued to the playback terminal 2. Is determined (S143).

  If there is no session identifier SID (NO in S143), the playback terminal 2 receives that fact (S212), waits for a predetermined period (S213), and makes an inquiry again (S211).

  On the other hand, if there is a session identifier SID (YES in S143), the server 1 encrypts the session identifier SID using the public key K1P (S129) and transmits it to the playback terminal 2 instead of the mobile phone 3 (S130).

[Fifth Embodiment]
In the fourth embodiment, the playback terminal 2 acquires the session identifier SID from the server 1 by polling. However, as shown in FIG. 16, the server 1 sends the session identifier SID to the playback terminal 2 by itself. You may do it. In order to realize this, the server 1 needs to know the network address of the playback terminal 2, but network traffic due to polling can be reduced.

In the fifth embodiment, the server 1 further includes a client location DB as shown in Table 7. In the client location DB, an IP (Internet Protocol) address is registered in association with the client ID. Instead of the IP address, a host name that can be resolved by a DNS (Domain Name System) assigned to each playback terminal 2 may be registered.

  In this case, as shown in FIG. 17, the server 1 refers to the client location DB without waiting for an inquiry from the reproduction terminal 2, identifies the reproduction terminal 2 by the IP address corresponding to the client identifier CLID, and reproduces the reproduction. The session identifier K1P (SID) encrypted with the public key K1P is transmitted to the terminal 2 (S130).

  In the above embodiment, the server is composed of one computer, but in order to distribute the load, for example, one server having only a content database is provided, and further, a content key database and a content meta database are provided. Another server having a license management database and a session management database may be provided.

  In the above embodiment, the session identifier SID is encrypted. However, it may not be encrypted if security is sacrificed. In this case, the public key K1P may be transmitted in step S203 instead of step S341.

  Moreover, although the said embodiment demonstrated the music content as an example, a video content or these combination may be sufficient.

  In the above embodiment, the server 1 immediately deletes the session identifier SID and corresponding information from the session management DB 18 after transmitting the content data D, but the playback terminal 2 fails to receive the content data D. In consideration of the situation, after the transmission of the content data D, these may be deleted after a predetermined period (for example, 1 minute). Further, when the playback terminal 2 fails to receive the content data D, the mobile phone 3 may be notified to that effect, and the user may be prompted to reissue the session identifier SID.

  While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

1 is a network diagram showing an overall configuration of a content distribution system according to a first embodiment of the present invention. It is a functional block diagram which shows the structure of the server in the content delivery system shown in FIG. It is a functional block diagram which shows the structure of the reproduction | regeneration terminal in the content delivery system shown in FIG. It is a functional block diagram which shows the structure of the mobile telephone in the content delivery system shown in FIG. It is a flowchart which shows the purchase operation | movement of the music content by the server and mobile telephone in the content delivery system shown in FIG. It is a flowchart following FIG. FIG. 7 is a transition diagram of screens displayed on the mobile phone during the purchase operation shown in FIGS. 5 and 6. It is a flowchart which shows the reproduction | regeneration operation | movement of the music content by the server and mobile telephone in the content delivery system shown in FIG. It is a flowchart following FIG. FIG. 10 is a flowchart following FIG. 9. FIG. 11 is a transition diagram of screens displayed on the mobile phone during the reproduction operation shown in FIGS. 8 to 10. It is a figure which shows the reproduction | regeneration terminal and mobile telephone in the 2nd Embodiment of this invention. It is a figure which shows the outline | summary of operation | movement by the reproduction | regeneration terminal and mobile telephone in the 3rd Embodiment of this invention. It is a figure which shows the outline | summary of operation | movement by the content delivery system by the 4th Embodiment of this invention. It is a flowchart which shows the transmission / reception operation | movement of the session identifier in the content delivery system shown in FIG. It is a figure which shows the outline | summary of operation | movement by the content delivery system by the 5th Embodiment of this invention. It is a flowchart which shows the transmission / reception operation | movement of the session identifier in the content delivery system shown in FIG.

Explanation of symbols

1 Server 2 Playback terminal 3 Mobile phone 4 Internet 14 Content data DB
15 Content key DB
16 Content metadata DB
17 License management DB
18 Session management DB
CID Content identifier SID Session identifier UID User identifier D Content data K1P Public key K1S Private key K2 Common key

Claims (9)

A content distribution system comprising a server, a client accessible to the server, and a portable information terminal accessible to the server,
The server
A content data database for storing content data in association with the content identifier;
Means for issuing a session identifier corresponding to desired content in response to a request from the portable information terminal;
Means for registering the issued session identifier in a session management database in association with a content identifier of desired content;
The session management database is referred to in response to a request from the client, a content identifier corresponding to the session identifier transmitted from the client is specified, content data corresponding to the content identifier is read from the content data database, and Content transmitting means for transmitting to the client,
The client
Means for receiving a session identifier issued by the server;
Content request means for transmitting the received session identifier to the server and requesting the server to transmit content data of desired content;
Reproducing means for reproducing the content data transmitted from the server,
The portable information terminal
A content distribution system comprising means for requesting the server to issue a session identifier corresponding to a desired content in response to a user operation. The content distribution system according to claim 1,
The server further includes:
A content distribution system comprising: means for deleting the session identifier from the session management database after transmission of the content data. The content distribution system according to claim 1 or 2,
The server further includes:
Means for encrypting the issued session identifier with a public key assigned to the client;
The client further includes:
A content distribution system comprising: means for decrypting the received session identifier with a secret key paired with the public key. The content distribution system according to claim 1,
The server further includes:
Means for encrypting a common key with a public key assigned to the client;
Means for encrypting content data to be transmitted to the client with a common key;
The client further includes:
Means for decrypting the encrypted common key transmitted from the server with a secret key paired with the public key;
Means for decrypting the encrypted content data transmitted from the server with the decrypted common key. The content distribution system according to claim 1,
The server further includes:
A license management database for storing content identifiers in association with user identifiers;
Means for referring to the license management database, identifying one or more content identifiers corresponding to one user identifier, and transmitting a list of contents corresponding to the content identifier to the portable information terminal;
The portable information terminal further includes:
Means for displaying a list of contents transmitted from the server;
And a means for selecting desired content from the displayed content list in accordance with a user operation.   The server used for the content delivery system of any one of Claims 1-5.   The client used for the content delivery system of any one of Claims 1-5.   The portable information terminal used for the content delivery system of any one of Claims 1-5. A content distribution method using a server, a client accessible to the server, and a portable information terminal accessible to the server,
Requesting the server from the portable information terminal to issue a session identifier corresponding to desired content in response to a user operation;
Issuing a session identifier corresponding to the desired content in response to a request from the portable information terminal;
Registering the issued session identifier in a session management database in association with a content identifier of desired content;
Sending the issued session identifier to the client;
Transmitting the transmitted session identifier from the client to the server, and requesting the server from the client to transmit content data of desired content;
The session management database is referred to in response to a request from the client, a content identifier corresponding to the session identifier transmitted from the client is specified, content data corresponding to the content identifier is read from the content data database, and the server Sending to the client from;
Playing back the content data transmitted from the server with the client.

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