JP5318241B2 - Content playback apparatus, method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve convenience of a user by permitting legitimate copying of contents on a recording medium and permitting the user to reproduce only the legitimate contents regardless of the kinds of recording mediums. <P>SOLUTION: A content reproduction device continues reproduction of contents when a hash value included in a content certificate matches a hash value calculated from the contents, and stops reproduction of the contents when a combination of a certificate kind and a kind of storage medium is not legitimate, the hash value included in the content certificate does not match the hash value calculated from the contents or a digital watermark is embedded in the contents. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a content reproduction apparatus, method, and program.

  Conventionally, in order to prevent unauthorized copying of content recorded on a ROM type recording medium such as a DVD, the copyright protection of the content has been achieved by a CSS (Content Scramble System) method that scrambles the content. . Similarly, for content on a recording medium, copyright protection has been achieved by a CPRM (Content Protection for Recordable Media) method or the like.

  However, such conventional copyright protection technology can effectively prevent unauthorized copying of content recorded on a DVD, but it is effective for infringement of content copyright that has been performed in recent years. I can not cope.

  That is, in recent years, the so-called pirated DVD content has been distributed in which a DVD player that reproduces DVD content is illegally modified, the scramble process is removed from the DVD content, and the plaintext content is copied to another recording medium such as a DVD. It has been broken. In addition, there is an act of infringing on the copyright of the content such as illegal file exchange of the content to Peer to Peer using the Internet. The content cannot be effectively protected against the act.

  For this reason, the Advanced Access Content System (AACS) technology, which is considered for next-generation DVD video such as HD DVD, has illegally recorded the content even after the content recorded on the media becomes plaintext. In order to detect whether or not it is a content, a content certificate technology (Content Certificate Technology (CC technology)) is employed, in which a digital watermark is embedded in the content and a certificate with a signature is added to the content and recorded on the medium. (See Non-Patent Document 1).

  In this CC technology, a content certificate is created by partially hashing content and cryptographically signing the hash value with a secret key possessed by a license organization. In addition, a digital watermark (Water Mark: WM) is embedded in the content in advance when the content is produced, and the content is encrypted and recorded on the medium together with the content certificate. On the other hand, a public key corresponding to the private key used for signing the content certificate is embedded in the content player (DVD player), and the content certificate is verified when viewing the content certificate. In addition to checking that the hash value in the content certificate has not been altered, the player calculates the hash value of the content during playback, and checks whether the hash value in the content certificate matches the value. Also, if the content certificate does not exist on the media, or if verification of the signature in the content certificate fails, digital watermark detection is performed during playback, and playback is stopped if a digital watermark is detected. By doing so, the legitimacy of the content can be confirmed.

  As a result, even if the content originally encrypted by the illegally modified DVD player as described above is converted into plain text and a pirated media recorded on the media is produced, when played on a regular DVD player, Since there is no content certificate, it is possible to detect that the medium is a pirated medium and detect the digital watermark by detecting the digital watermark. Also, the content originally encrypted by an illegally modified DVD player is converted into plain text, and further encrypted by an illegally modified recorder, as if it were a medium on which regular encrypted content was recorded. Even if it is a fake pirated media, the content cannot be signed unless it is a private key owned by the licensing organization, so the content certificate cannot be forged, and when played on a regular DVD player, By failing to verify the content certificate and detecting the digital watermark, it is possible to detect the pirated media and stop the reproduction. In addition, the content certificate verification processing is performed only for video content, that is, read-only ROM media (Pre-recorded media), and for writable recording media, digital watermark verification processing is performed regardless of the presence of the content certificate. Thus, even if the content certificate is simply copied from the regular ROM medium to the recordable medium, the reproduction can be stopped to detect the digital watermark detection process.

Advanced Access Content System (AACS) Pre-recorded Video Book Revision 0.90 (Chapter 2, Chapter 3)

  By the way, if the content on the media can be copied in the future in compliance with certain rules, the user can use the content without physically carrying the media by copying it to the HDD or the like. It can be used, and even if the copy source medium is physically damaged, a backup can be created.

  However, since the content certificate technology described above is only intended for the protection of the content recorded on the ROM media, the content certificate is recorded on the recordable media by a legitimate method, or the content of the recordable media is not reproduced. It is not possible to check whether it is legitimate.

  The present invention has been made in view of the above, and while allowing the legitimate copying of content to a recording medium, allows reproduction of only legitimate content regardless of the type of the recording medium. It is an object of the present invention to provide a content reproduction apparatus, method, and program capable of improving convenience.

In order to solve the above-described problems and achieve the object, the present invention provides a content reproduction apparatus for reproducing content recorded on a recording medium and encrypted with a first encryption key, wherein the first encryption A reproduction unit that decrypts the content using a key and reproduces the decrypted content; a certificate type in which a content type indicating a type of recording of the content on the recording medium is registered; and a part of the content Verifying whether or not a content certificate including a signature generated by a second encryption key with respect to the hash value based on the information of the information and the certificate type and the hash value exists in the recording medium, When the content certificate exists in the recording medium, the certificate type of the content certificate recorded on the recording medium and the type of the recording medium are a valid combination. The hash value included in the content certificate is calculated from the content when the certificate verification unit for determining whether or not the certificate is valid and the certificate type and the recording medium type are a valid combination. A hash value verifying unit that verifies whether or not the hash value matches with the hash value, and whether or not a digital watermark is embedded in the content during playback of the content when the content certificate does not exist in the recording medium A digital watermark verification unit that determines whether or not the reproduction unit reproduces the content when the hash value included in the content certificate matches a hash value calculated from the content. Continuing, if the certificate type and the recording medium type are not a valid combination, or the content certificate includes If Mesh value does not match the calculated hash value from the content, or, when said electronic watermark is embedded in the content, characterized by stop playback of the content.
The present invention also relates to a method and a program executed by the content reproduction apparatus.

  According to the present invention, it is possible to allow legitimate copying of content to a recording medium, and to allow the reproduction of only legitimate content regardless of the type of recording medium, thereby improving user convenience. There is an effect.

1 is a block diagram showing a configuration of a content recording / playback apparatus 100 according to a first exemplary embodiment. FIG. 3 is a data structure diagram of a content certificate in the first embodiment. 3 is a flowchart illustrating a procedure of content copy processing according to the first embodiment. 3 is a flowchart illustrating a procedure of content reproduction processing according to the first embodiment. 3 is a flowchart illustrating a procedure of content reproduction processing according to the first embodiment. 5 is a flowchart illustrating a procedure of consistency verification processing between a content certificate and media according to the first embodiment. FIG. 5 is a block diagram showing a functional configuration of a DVD recorder 700 according to a second embodiment. 10 is a flowchart illustrating a copy processing procedure according to the second embodiment; 10 is a flowchart illustrating a procedure of a move process according to the second embodiment. It is a data structure figure of the content certificate concerning Embodiment 3. FIG. 4 is an explanatory diagram showing a recording source DVD medium and content type, a recording destination DVD medium, an action, and a certificate type of a requested content certificate. 15 is a flowchart illustrating a copy processing procedure according to the third embodiment. 15 is a flowchart illustrating a copy processing procedure according to the third embodiment. 10 is a flowchart illustrating a procedure of a move process according to the third embodiment. 10 is a flowchart illustrating a procedure of a move process according to the third embodiment. 14 is a flowchart illustrating a procedure of a content certificate / media consistency verification process according to the third embodiment.

  Exemplary embodiments of a content reproduction apparatus, method, and program according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a block diagram of the configuration of the content recording / playback apparatus 100 according to the first embodiment. Here, examples of the content recording / reproducing apparatus 100 include a DVD / HD DVD recorder that performs recording and reproduction on an HD DVD medium (hereinafter referred to as “DVD medium”). A content recording / playback apparatus 100 (hereinafter referred to as “DVD recorder 100”) according to the first embodiment is connected to a copy permission server 200 via a network 300 such as the Internet.

  As shown in FIG. 1, the DVD recorder 100 according to the present embodiment records data on a recordable DVD 172 to which data can be written, or reads data from a recordable DVD 172 or a read-only DVD-ROM 171. And a host unit 120 that performs content title key encryption processing, decryption processing, and the like. The drive unit 110 and the host unit 120 are connected by a general-purpose bus or a dedicated special bus.

  The copy permission server 200 receives the copy permission request from the DVD recorder 100 and authenticates the DVD recorder. When the authentication is successful, the copy permission server 200 permits the DVD recorder 100 to copy the content and A computer that generates and transmits a content certificate for proof of content.

  As shown in FIG. 1, the DVD-ROM 171 records in advance a media type, a copy management file, a content certificate, a title key file (TKF), a media key block (MKB), and an encrypted content embedded with a digital watermark. Has been. Here, the DVD-ROM 171 is a medium on which data is recorded in the manufacturing process and a general user cannot arbitrarily add or overwrite data.

  The media type indicates whether the DVD medium is a recording type or a read-only type, and “DVD-ROM”, which is a read-only type, is recorded on the DVD-ROM 171.

  The copy management file is a file that describes an address (URL) on the network of the copy permission server 200 and information on the copy destination medium for which copying is permitted.

  The title key file (TKF) is a file in which a plurality of encrypted title keys obtained by encrypting respective title keys corresponding to a plurality of title contents with a media key described later are registered. The title key is a key for encrypting the title content.

  A media key block (MKB) is a set of media keys that can be calculated by a regular DVD player. For a regular DVD player, a media key can be derived by processing the MKB using a device secret key issued by a license institution. The encrypted content is data encrypted with the title key. Even after the encrypted content recorded on the medium becomes plaintext, in order to verify whether or not the content is illegally recorded, a digital watermark is embedded in the content.

  The content certificate is data that is bound (associated) with the content and has signed the content in order to guarantee the validity of the binding.

  FIG. 2 is a data structure diagram of the content certificate in the first embodiment. As shown in FIG. 2, the content certificate of the present embodiment includes a certificate type, a content sequence number for uniquely specifying content, a content revocation list, a content hash value, and a signature following the header. It is.

  The content revocation list is a list in which content sequence numbers of content illegally created by pirates are described. The version of the content revocation list is managed, and the DVD player stores the latest version of the content revocation list in the device.

  The content hash value is a hash value that is an output obtained by applying a one-way function to a part of the content. If the content is different, the hash value is also different, so the content certificate and the content can be associated one-to-one.

  The signature is data obtained by applying an electronic signature to the above-described content sequence number, content revocation list, content hash value, and later-described certificate type using a private key in public key cryptography owned by a predetermined license authority. is there. By performing the verification process using the public key corresponding to the private key, it is possible to verify whether the data included in the content certificate has been altered.

  In the present embodiment, a certificate type field is further provided in the content certificate. This certificate type indicates the type of certificate, and in this embodiment, indicates the type of DVD medium on which the content certificate is recorded. In FIG. 2, as an example, when the certificate type is “0”, it indicates that the content certificate is for DVD-ROM, and when it is “1”, it indicates that it is a content certificate for recordable DVD. ing.

  Also, as shown in FIG. 1, the recording type DVD 172 records only the media type and the media ID before the content copy process. The media ID is a value uniquely assigned at the time of media manufacture, and is recorded in an area where the user cannot freely rewrite, for example, (Lead-In area or Read-Only area). The media type is also recorded in an area where the user cannot freely rewrite, and the recordable DVD 172 records “recordable DVD” which is a read / write medium as the media type.

  Next, details of the DVD recorder 100 according to the present embodiment will be described. The drive unit 110 mainly includes a reading unit 112 and a recording unit 113. The reading unit 112 performs processing for reading data recorded on the DVD-ROM 171 such as a content certificate, MKB, TKF, and encrypted content. Further, the reading unit 112 performs a process of reading the media ID from the recordable DVD 172.

  The recording unit 113 performs processing for recording data such as encrypted content read from the DVD-ROM 171 and data such as a content certificate received from the copy permission server 200 on the recordable DVD 172.

  The host unit 120 mainly includes a copy management unit 140, a reproduction processing unit 150, a signature verification unit 161, a recording medium determination unit 162, a certificate verification unit 163, a communication processing unit 164, and a key storage unit 167. In preparation.

  The copy management unit 140 is a processing unit that controls copying of content to the recordable DVD 172, and includes a management file processing unit 141, a certificate receiving unit 142, and a copy request unit 143.

  The management file processing unit 141 analyzes the copy management file recorded on the copy source DVD medium (DVD-ROM 171), and the address on the network of the copy permission server 200 that executes communication processing to obtain permission for copying. It is a processing unit that acquires (URL) and the like.

  The copy request unit 143 transmits a copy permission request message for requesting permission to copy content from the DVD-ROM 171 to the recordable DVD 172 for the address of the copy permission server 200 instructed by the management file processing unit 141. Part.

  The certificate receiving unit 142 receives the authentication result from the copy permission server 200, and receives data such as a content certificate from the copy permission server 200 when receiving a message indicating that copying is permitted due to successful authentication. It is a processing unit.

  The reproduction processing unit 150 includes a content reproduction unit 151, a hash value verification unit 152, a bind determination unit 153, a digital watermark verification unit 154, and an encryption processing unit 155.

  The encryption processing unit 155 decrypts the encrypted title key by using the device secret key stored in the MKB and the key storage unit 167, and decrypts the encrypted content by using the decrypted title key. Is to do.

  The content reproduction unit 151 is a processing unit that inputs the plaintext content processed by the encryption processing unit and decodes it into uncompressed data or performs digital / analog conversion to reproduce it.

  The hash value verification unit 152 is a processing unit that calculates a hash value of the content and verifies whether the value matches the hash registered in the content certificate. If the verification fails, the hash value verification unit 152 notifies the content playback unit that playback is to be stopped.

  The digital watermark verification unit 154 performs processing for detecting a digital watermark embedded in the content and stopping the reproduction. Specifically, when a digital watermark is detected, the content playback unit 151 is notified that playback is to be stopped.

  The bind determination unit 153 is a processing unit that verifies whether or not the content certificate or various types of key information is bound to (associated with) the DVD medium.

  Here, the bind information will be described. In order to prevent the content and content certificate from being copied from the recordable DVD to another recordable medium, it is necessary to bind (associate) the content and the content certificate to the media ID unique to the recordable DVD 172 to record the content. . For this reason, the DVD recorder 100 transmits the media ID to the copy permission server 200, and the copy permission server 200 calculates the bind information based on the media ID and sends it back to the DVD recorder 100. Then, in the content reproduction processing by the DVD recorder 100, the bind determination unit 153 determines whether the content certificate or the various key information is stored in the DVD medium by determining whether or not the bind information transmitted from the copy permission server 200 matches. Validating whether it is bound or not.

  There are the following three methods for binding content to a recordable DVD. The first method is a method of binding the content certificate and the media ID, and the second method is a method of binding the key information and the media ID. The third method is a combination of the first method and the second method.

  As an example of the first method, the content certificate is bound by the expression (1) using the media ID by the function f.

Bind information = f (content certificate, media ID) (1)
Here, the function f may be calculated by a method using an encryption algorithm such as AES, a method using a hash function such as SHA-1, or a combination of these. Further, parameters other than the media ID may be included as parameters of the function f.

  Alternatively, a media ID area may be defined in the content certificate, and a signature may be generated using a secret key issued from a predetermined license authority together with the media ID.

  As an example of the second method, the key information is bound by Expression (2) using the media ID by the function f2. Media_Key is a value calculated from the MKB using the device secret key according to the equation (3), and the title key is encrypted using this Media_key.

Bind information = f2 (Media_Key, media ID) (2)
Media_Key = g1 (device secret key, MKB) (3)
Here, the function f2 may be calculated by a method using an encryption algorithm such as AES, a method using a hash function such as SHA-1, or a combination of these. Further, parameters other than the media ID may be included as parameters of the function f2.

  In addition, the media ID may be directly included in the calculation of the key for encrypting the title key by modifying (3) as shown in equation (4).

Media_Key = g2 (device secret key, MKB, media ID) (4)
The process by the copy management unit 140 described above is executed in the process of copying content to the recordable DVD 172. On the other hand, the processing by the reproduction processing unit 150 is executed when content recorded on the DVD-ROM 171 or content copied to the recordable DVD 172 is reproduced. The following processes by the signature verification unit 161, the recording medium determination unit 162, the certificate verification unit 163, and the communication processing unit 164 are executed in common for the copy process and the reproduction process.

  The signature verification unit 161 is a processing unit that verifies the validity of the signature included in the content certificate, and controls the operation of the digital watermark verification unit 154 according to the verification result of the content certificate.

  The recording medium determination unit 162 is a processing unit that determines whether the recording medium is a DVD-ROM or a recording type DVD from the media type recorded on the DVD-ROM 171 and the recording type DVD 172 (hereinafter referred to as “DVD medium”).

  The certificate verification unit 63 is a processing unit that verifies whether the media type recorded on the DVD medium matches the certificate type registered in the content certificate.

  The communication processing unit 164 is a processing unit that executes physical layer processing, data link layer processing, network layer, and transport layer processing for communicating with the copy permission server 200.

  The key storage unit 167 is a storage medium such as a memory for storing a device private key or public key issued from a predetermined license authority, or a key for performing authentication processing with the copy permission server. Here, the device secret key is a key used for the MKB decryption process. The public key is a key used for verifying the signature of the content certificate. This device secret key is preferably stored so as not to leak outside the DVD recorder 100.

  Also, the private key used to generate the signature of the content certificate is held by a predetermined license authority or copy permission server 200 that generates the signature, and the public key is a key corresponding to this private key. That is, the DVD recorder 100 has a public key for signature verification, but does not have the private key that generated the signature. Therefore, when copying the content to the recordable DVD 172, the content certificate is illegally copied. It cannot be generated.

  Next, content copy processing according to the present embodiment configured as described above will be described. In the present embodiment, processing for copying the content of the DVD-ROM 171 to the recordable DVD 172 is performed. FIG. 3 is a flowchart showing a procedure of content copy processing according to the first embodiment.

  First, the recording medium determination unit 162 checks whether the media type of the copy source DVD medium is a DVD-ROM (step S11). If the media type is not a DVD-ROM, that is, if it is a recordable DVD, copy of the content is not permitted, so error processing is performed (step S20), and the copy processing is stopped.

  On the other hand, if the media type is DVD-ROM, the certificate verification unit 163 checks whether the certificate type of the content certificate is for DVD-ROM (step S12). If the certificate type is not for a DVD-ROM, that is, for a recordable DVD (step S12: No), no further copy permission is allowed, and error processing is performed (step S20). Cancel the copy process.

  Next, the signature verification unit 161 verifies the signature of the content certificate using the public key stored in the key storage unit 167 (step S13). If the verification fails as a result of the verification (step S14: No), it is determined that the DVD medium is an illegal DVD medium, an error process is performed (step S20), and the copy process is stopped. On the other hand, if the signature verification is successful (step S14: Yes), the copy request unit 143 transmits a copy permission request message to the copy permission server 200 (step S15).

  The copy permission server 200 authenticates the DVD recorder 100. Such authentication processing may be configured such that the copy permission server 200 and the DVD recorder 100 perform two-way authentication in addition to one-way authentication in which the copy permission server 200 authenticates the DVD recorder 100. It is also possible to perform billing processing at the stage of such authentication processing.

  If an authentication result failure is received (step S16: No), the error processing is performed because the DVD recorder 100 is invalid (step S20), and the copy process is stopped.

  On the other hand, when the success of the authentication result is received from the copy permission server 200 (step S16: Yes), the copy request unit 143 sends a content certificate request message to the copy permission server 200 as a recording destination recording type. It is transmitted together with the media ID of the DVD (step S17).

  As a result, the content certificate, MKB, and TKF for the recordable recording type DVD 172 are transmitted from the copy permission server 200, and these are received by the certificate receiving unit 142 (step S18).

  Here, the content certificate includes a signature for a partial hash value of the content. That is, in order to receive the content certificate recorded on the recordable DVD 172, the DVD recorder 100 needs to notify the copy permission server 200 of what hash value the signature is to be given to. is there. As a method for notifying information related to the hash value, a first method for transmitting a content sequence number, a second method for transmitting partial information of content to be hashed, the DVD recorder 100 calculates hash information of the content, A third method for transmitting the hash information itself, a fourth method for transmitting a content certificate recorded on the DVD-ROM 171, a fifth method for transmitting information combining the first to fourth methods, and the like There is.

  In the case of the first method, the copy permission server 200 previously records a content sequence number and a content certificate as a pair, and transmits a content certificate corresponding to the content sequence number transmitted from the DVD recorder 100. By calculating the signature of this content certificate in advance, it is possible to respond immediately upon request. In addition, if the content certificate signature is generated by a predetermined license authority and the copy permission server 200 stores the signed content certificate, the copy permission server 200 does not need to manage the secret key. Key distribution range can be narrowed.

  In the case of the second method, the copy permission server 200 receives content partial information from the DVD recorder 100, calculates a hash value from the content partial information, generates a content certificate including the hash value, A signature is immediately generated using a secret key issued from the license institution of No. 1 and a content certificate is transmitted to the DVD recorder 100.

  In the case of the third method, a signature is added to the hash value received from the DVD recorder 100 to generate a content certificate, and a signature is immediately generated using a secret key issued from a predetermined license authority. The content certificate is transmitted to 100.

  In the case of the fourth method, the certificate type of the received content certificate is rewritten from DVD-ROM to recordable DVD, a signature is generated using a private key, and the content certificate is transmitted to the DVD recorder 100 To do.

When the content data of the DVD-ROM is copied as it is when recording on the recordable DVD, the hash value does not change. Therefore, the hash information is copied using any one of the first to fourth methods. May be notified.
When data is transmitted from the DVD recorder 100 to the copy permission server 200 using any one of the first to fourth methods, the data is encrypted or transmitted with a signature to ensure that the data has not been altered. You may do it.

When recording on the recordable DVD 172, if the content of the DVD-ROM 171 is subjected to format conversion or re-encoding to another compression format, the hash value is different between the original content and the converted content. Become. In such a case, notification may be made using the second and third methods.
Further, when the fourth method is used, the copy permission server 200 checks whether the certificate type of the content certificate is for DVD-ROM and performs processing for verifying the signature of the content certificate. For example, the DVD recorder 100 does not necessarily need to perform the above processing (steps S12 to S14). In this case, the signature verification unit 161 and the certificate verification unit 163 are not necessarily required in the host unit.

Then, the process returns to step S19, and the recording unit 113 copies the content of the DVD-ROM 171 by recording it on the recordable DVD 172 (step S19). At this time, the content certificate, MKB, and TKF for the recordable DVD 172 received from the copy permission server 200 are also recorded on the recordable DVD 172. As a result, the content of the DVD-ROM is legitimately copied to the recordable DVD 172.
In the present embodiment, an example in which MKB and TKB are transmitted from the copy permission server 200 is shown. However, the MKB stored in the copy permission server 200 and the MKB version of the DVD-ROM 171 are compared to determine the DVD. When the MKB version of the ROM 171 is newer, the MKB and TKF recorded on the DVD-ROM 171 may be copied to the recordable DVD 172.

  Next, content reproduction processing according to Embodiment 1 will be described. 4 and 5 are flowcharts showing the procedure of the content reproduction process according to the first embodiment. Here, the process of reproducing the content copied to the recordable DVD 172 will be described.

  First, the certificate verification unit 163 checks whether a content certificate exists on the DVD medium (recordable DVD) (step S31). When the content certificate exists (step S31: Yes), the consistency verification process between the content certificate and the media is performed (step S32). Details of the content certificate and media consistency verification process will be described later.

  If the verification of the consistency between the content certificate and the media fails (step S33: No), the content reproduction may be stopped because there is a possibility that the content certificate is illegally generated (step S44). Then, error processing is performed (step S45).

  On the other hand, when the consistency verification between the content certificate and the media is successful (step S33: Yes), the revocation list of the content certificate is confirmed (step S34), and the content sequence number included in the content certificate is the content. It is checked whether the certificate exists in the content revocation list (step S35). If the content sequence number exists in the content revocation list (step S35: Yes), it is determined that the content is a pirated DVD medium, the reproduction of the content is stopped (step S44), and an error process is performed (step S44). S45).

  On the other hand, if the content sequence number does not exist in the content revocation list (step S35: No), the encryption processing unit 155 decrypts the encrypted title key included in the TKF using the device secret key and MKB, and the title key Is obtained (step S36).

  Next, the bind determination unit 153 performs the above-described calculation of the bind information to verify the bind information (step S38), and whether the calculated bind information matches the bind information transmitted from the copy permission server 200. To determine whether the content certificate or various key information is bound to the DVD medium (step S39). If the binding information does not match (step S39: No), the reproduction process is stopped (step S44), and an error process is performed (step S45).

  On the other hand, if the binding information matches (step S39: Yes), the encryption processing unit 155 decrypts the encrypted content of the recordable DVD 172 with the title key, and the content reproduction unit 151 decrypts the decrypted content. Playback is started (step S40).

  When the reproduction of the content is started, the hash value verification unit 152 calculates the content hash value and verifies it (step S41). Then, it is checked whether or not the hash value included in the content certificate matches the calculated value (step S42). If the hash does not match (step S42: No), the reproduction of the content is stopped (step S44). ), Error processing is performed (step S45).

  On the other hand, if the hashes match in step S42 (step S42: Yes), the content is continued (step S43).

  Returning to step S31, a case where no content certificate exists on the recordable DVD 172 will be described. When the content certificate does not exist on the recordable DVD 172 (step S31: No), the content reproduction unit 151 starts reproduction of the content (step S46).

  Then, the digital watermark verification unit 154 detects whether or not a digital watermark is embedded in the content (step S47). Thereby, when the digital watermark embedded in the content is detected (step S47: Yes), it is determined that the content is illegally recorded, the reproduction of the content is stopped (step S49), and error processing is performed. Is performed (step S50).

  On the other hand, while the digital watermark embedded in the content is not detected in step 47 (step S47: No), the reproduction of the content is continued (step S48).

  Next, the content certificate and media consistency verification processing in step S32 will be described. FIG. 6 is a flowchart showing the procedure of the content certificate / media consistency verification process according to the first embodiment.

  First, the media type is acquired from the DVD medium (step S61), and then the value of the certificate type field of the content certificate recorded on the DVD medium is acquired (step S62). Then, it is checked whether or not the media type and the certificate type field value match (step S63).

  If they do not match, it is determined that the content certificate has been illegally generated, and a verification failure is returned as a return value (step S67).

  On the other hand, if they match, the signature verification unit 161 verifies the signature of the content certificate (step S64). If the verification result is a verification failure, it is determined that the content certificate has been illegally generated, and the verification failure is returned as a return value (step S67). On the other hand, if the verification result is a verification success, the verification success is returned as a return value (step S66). Such a return value is determined in step S33 described above.

  As described above, in the DVD recorder 100 according to the first embodiment, when copying content to another DVD medium, a copy permission request is made to the copy permission server 200 and a content certificate for a recordable DVD is received. Since the content is copied to the recordable DVD 172 together with the received content certificate, it is possible to realize a valid copy of the content and to reproduce the content even if the content certificate is copied by an unauthorized DVD recorder. At times, playback can be stopped and content can be prevented from being duplicated due to unauthorized copying of the content certificate.

  In the DVD recorder 100 according to the first embodiment, when copying content to the recordable DVD 172, a copy permission request is made to the copy permission server 200 to authenticate the DVD recorder, and the authentication is successful. In addition, since the copying process to the recordable DVD 172 is executed, it is possible to detect in advance that content is copied by an unauthorized DVD recorder, and unauthorized copying of content can be prevented in advance.

  Furthermore, in the DVD recorder 100 according to the first embodiment, a content certificate including a signature using a private key in public key encryption owned by a license authority is recorded on a DVD medium, and the DVD recorder creates a signature for the content certificate. Since it does not have a private key, even if the content certificate is illegally generated and the content is illegally copied, it can be detected that the content is illegal when the content is played back. It is possible to prevent the content from being reproduced.

(Embodiment 2)
In the DVD recorder according to the first embodiment, the content of the DVD-ROM is copied to a recordable DVD. In the second embodiment, the content of the DVD-ROM is temporarily copied to the data storage unit of the DVD recorder. Thereafter, the contents of the data storage unit are moved to a recordable DVD.

  FIG. 7 is a block diagram of a functional configuration of the DVD recorder 700 according to the second embodiment. The DVD recorder 700 according to this embodiment is connected to the copy permission server 200 and the move permission server 400 via a network such as the Internet.

  The copy permission server 200 is the same server as in the first embodiment, and the move permission server 400 receives the move permission request from the DVD recorder 700, authenticates the DVD recorder, and when the authentication is successful, the DVD recorder This is a computer that grants content move permission to 700 and generates and transmits a content certificate for proof of content for a recording destination medium.

  In the present embodiment, the content certificate recorded on the DVD medium has the same data structure as in the first embodiment.

  As shown in FIG. 7, the DVD recorder 700 according to the present embodiment records data on a recordable DVD 172 to which data can be written, or reads data from the recordable DVD 172 or a read-only DVD-ROM 171. And a host unit 720 that performs content title key encryption processing, decryption processing, and the like. The drive unit 110 and the host unit 720 are connected by a general-purpose bus or a dedicated special bus.

  The host unit 720 includes a copy management unit 740 that controls content copying and movement, a playback processing unit 150 that performs content playback processing, a signature verification unit 161, a recording medium determination unit 162, and a certificate verification unit 163. And a communication processing unit 164, a key storage unit 167, and a data storage unit 701.

  Here, the functions of the reproduction processing unit 150, the signature verification unit 161, the recording medium determination unit 162, the certificate verification unit 163, the communication processing unit 164, and the key storage unit 167 are the same as those in the first embodiment.

  The data storage unit 701 is a storage medium such as a hard disk drive (HDD) or a memory that stores data such as encrypted content, title key files (TKF), and content certificates recorded on a DVD medium.

  The copy management unit 740 includes a management file processing unit 141, a certificate reception unit 142, a copy / move request unit 743, and an encryption processing unit 744. Here, the function of the management file processing unit 141 is the same as that of the first embodiment.

  When performing a content copy process, the copy / move request unit 743 requests a copy asking for permission as to whether or not the content can be copied to the address of the copy permission server 200 instructed by the management file processing unit 141. Send an authorization request message. On the other hand, the copy / move request unit 743 grants permission to move the content to the address of the move permission server 400 instructed by the management file processing unit 141 when performing the content move process. Send the requested move permission request message.

  The certificate receiving unit 142 receives the authentication result from the copy permission server 200, and receives data such as a content certificate from the copy permission server 200 when receiving a message indicating that copying is permitted due to successful authentication. . When the certificate receiving unit 142 receives the authentication result from the move permission server 400 and receives a message indicating that the move is permitted due to successful authentication, the certificate receiving unit 142 receives data such as a content certificate from the move permission server 400. Receive.

  When it is determined that copying from the DVD-ROM to the data storage unit 701 is permitted, the encryption processing unit 744 performs content re-encryption processing. If it is determined that the move from the data storage unit 701 to the recordable DVD 172 is permitted, the encryption processing unit 744 performs re-encryption processing of the content stored in the data storage unit 701.

  Next, a copy process according to the second embodiment configured as described above will be described. First, the user instructs the operation unit (not shown) to copy or move content to the DVD recorder 700. When copying the content recorded on the DVD-ROM 171 to the data storage unit 701, the user gives a copy instruction from the operation unit (not shown). The DVD recorder 700 receives the user's copy instruction and executes the following copy process.

  FIG. 8 is a flowchart of a copy process procedure according to the second embodiment. First, the recording medium determining unit 162 checks whether the media type of the copy source DVD medium is a DVD-ROM (step S71). If the media type is not a DVD-ROM, that is, if it is a recordable DVD, no further content copying is permitted, so an error process is performed (step S78), and the copy process is stopped.

  On the other hand, if the media type is DVD-ROM, the certificate verification unit 163 checks whether the certificate type of the content certificate is for DVD-ROM (step S72). If the certificate type is not for a DVD-ROM, that is, for a recordable DVD (step S72: No), no further copy permission is permitted, and error processing is performed (step S78). Cancel the copy process.

  Next, the signature verification unit 161 verifies the signature of the content certificate using the public key stored in the key storage unit 167 (step S73). If the verification fails as a result of the verification (step S74: No), it is determined that the DVD medium is an illegal DVD medium, an error process is performed (step S78), and the copy process is stopped.

  On the other hand, if the signature verification is successful (step S74: Yes), the copy / move request unit 743 transmits a copy permission request message to the copy permission server 200 (step S75).

  The copy permission server 200 authenticates the DVD recorder 700. If an authentication result failure is received (step S76: No), an error process is performed because the DVD recorder 700 is invalid (step S78), and the copy process is stopped.

  On the other hand, when the authentication result success message is received from the copy permission server 200 (step S76: Yes), the recording unit 113 records the contents of the DVD-ROM 171 in the data storage unit 701 in the DVD recorder 700 (step S76). S77). As a result, the content in the DVD-ROM 171 is copied to the data storage unit 701.

  There are the following two methods for realizing such copy processing. As a first method, the encrypted title key in the TKF is decrypted using the device secret key stored in the key storage unit 167 and the MKB recorded in the DVD-ROM 171 and decrypted in the plaintext title. In this method, the key is bound to the DVD recorder 700. In order to bind the title key to the DVD recorder 700, the title key is encrypted using a key or ID unique to the DVD recorder 700 and recorded in the data storage unit 701. This corresponds to processing for re-encrypting the title key of TKF. The encrypted content is directly copied from the DVD-ROM 171 to the data storage unit 701 without being re-encrypted.

  As the second copy processing method, as in the content reproduction processing, the encrypted title key is decrypted, the encrypted content is decrypted using the decrypted plaintext title key, and the plaintext content is converted into the DVD recorder 700. It is a method to bind to. In order to bind the content to the DVD recorder 700, the content is encrypted using a key or ID unique to the DVD recorder 700 and recorded in the data storage unit 701. In the case of content format conversion or re-encoding to another compression format, it is necessary to adopt this method because the content needs to be once converted into plain text. In this method, since it is not necessary to use TKF for content decryption, it is not necessary to copy TKF to the data storage unit 701.

Here, since the content stored in the data storage unit 701 is encrypted with a key unique to the DVD recorder 700, a device secret key distributed from a predetermined license authority, A content certificate and content sequence number are not required. Therefore, when content is copied to the data storage unit 701, the content certificate need not be recorded in the data storage unit 701.
Therefore, it is not necessary to request a content certificate from the copy permission server 200. However, the DVD recorder 700 transmits a content certificate to the copy permission server 200, checks whether the certificate type of the content certificate is for DVD-ROM (step S72), and stores it in the key storage unit 167. By causing the copy permission server 200 to execute a process for verifying the signature of the content certificate using the stored public key (step S73), the DVD recorder 700 does not perform this process. This processing may be simplified.

  Next, a process for moving content copied to the data storage unit 701 to the recordable DVD 172 will be described. In this case, the user gives a move instruction to the DVD recorder 700 from an operation unit (not shown). The DVD recorder 700 receives the user's move instruction and executes the following move process.

  FIG. 9 is a flowchart of a move process procedure according to the second embodiment. When a move instruction is received from the user, first, the copy / move request unit 743 transmits a move permission request message to the move permission server 400 (step S81).

  The move permission server 400 authenticates the DVD recorder 700. As in the first embodiment, the authentication process may be performed in one direction in which the DVD recorder 700 is authenticated by the move permission server 400 or may be authenticated in both directions between the move permission server 400 and the DVD recorder 700. May be. It is also possible to perform billing processing at the stage of such authentication processing.

  Returning to step S82, if an authentication result failure is received (step S82: No), an error process is performed because the DVD recorder 700 is invalid (step S86), and the move process is stopped.

  On the other hand, when the success notification result is received from the move permission server 400 (step S82: Yes), the copy / move request unit 743 sends a content certificate request message to the move permission server 400 as a recording destination. It is transmitted together with the media ID of the recordable DVD 172 (step S83).

  Here, in order to record the content of the data storage unit 701 on the recordable DVD 172, a content certificate signed with a private key of a predetermined license organization is required. Since it is necessary to include a partial hash value of the content in the content certificate, information regarding the hash value to which the signature is given from the move permission server 400 and information on the hash value are sent to the move permission server 400. Need to be notified. There are the following five methods for notifying information on the hash value.

  The first method is a method for transmitting a content sequence number, and the second method is a method for transmitting content partial information. The third method is a method in which the DVD recorder 700 calculates a hash value of content and transmits the hash value itself. The fourth method is a method of transmitting the content certificate recorded on the DVD-ROM 171. The fifth method is a method of transmitting information obtained by combining the first to fourth information.

Here, in the case of performing content copy processing from the DVD-ROM 171 to the data storage unit 701, if content format conversion or re-encoding is not performed, the content on the DVD-ROM 171 can be partially copied to the data storage unit 701 as it is. The hash value does not change. That is, the hash value included in the content certificate necessary for the recordable DVD 172 may be exactly the same value as the content certificate on the DVD-ROM 171. Accordingly, when copying to the data storage unit 701 without performing format conversion or re-encoding of the content, the first method is adopted at the time of copy processing, and the first, In preparation for selecting the second method, a content sequence number or a content certificate is stored in the data storage unit 701 together with the content when the content is copied from the DVD-ROM 171 to the data storage unit 701. It is preferable. Further, when moving content from the data storage unit 701 to the recordable DVD 172, it is preferable to request a content certificate from the move permission server 400 by the first to fourth methods.
On the other hand, when the content is converted from the DVD-ROM 171 to the data storage unit 701 and the content format is converted or re-encoded, the content certificate is sent to the move permission server 400 by the second or third method. Request.

  Returning to step S84, when the move permission request message is transmitted, the content certificate, MKB, and TKF for the recording type recording DVD 172 are transmitted from the move permission server 400, and these are received by the certificate receiving unit 142. (Step S84).

  Then, the recording unit 113 moves the content of the data storage unit 701 by recording it on the recordable DVD 172 (step S85). At this time, if the content is copied from the DVD-ROM 171 to the data storage unit 701 by the first copy processing method, the TKF of the data storage unit 701 is deleted. If content has been copied from the DVD-ROM 171 to the data storage unit 701 by the second copy processing method, the content in the data storage unit 701 is deleted. Thereafter, the content certificate, MKB, and TKF for the recordable DVD 172 received from the move permission server 400 are also recorded on the recordable DVD 172. As a result, the contents of the data storage unit 701 are legally moved to the recordable DVD 172.

  Note that the process for reproducing the content recorded on the recordable DVD 172 in this manner is performed in the same manner as the reproduction process in the first embodiment described with reference to FIGS.

  As described above, in the DVD recorder 700 according to the second embodiment, when the content of the DVD-ROM 171 is temporarily copied to the data storage unit 701 of the DVD recorder 700 and then the content of the data storage unit is moved to the recordable DVD, A move permission request is made to the move permission server 400, a content certificate for a recordable DVD is received, the content is moved to the recordable DVD 172, and the received content certificate is recorded on the recordable DVD 172. Therefore, it is possible to realize a legitimate move process of content to the recordable DVD 172, and even when a content certificate is copied by an unauthorized DVD recorder, it can be detected at the time of content playback and the playback can be stopped. Content movement due to unauthorized movement of content certificate It is possible to prevent the manufacturing.

  Also, in the DVD recorder 700 according to the second embodiment, when content is moved to the recordable DVD 172, a move permission request is made to the move permission server 400 to authenticate the DVD recorder, and the authentication is successful. In addition, since the moving process to the recordable DVD 172 is executed, it is possible to detect in advance that the content is moved by an unauthorized DVD recorder, and the unauthorized movement of the content can be prevented in advance.

(Embodiment 3)
In the DVD recorder according to the first and second embodiments, the copy source content is recorded on a read-only DVD-ROM. However, with an increase in the speed of networks such as optical fibers and ADSL, it has become possible to distribute content via the network and record it on recordable media. In consideration of the convenience of the user, it is preferable that the downloaded content has a function equivalent to that of a package medium such as a DVD-ROM. That is, it is preferable that the recording medium also has a function that enables copying directly downloaded contents.

  In the first and second embodiments, the content copied from the DVD-ROM 171 is distinguished by whether the certificate type of the content certificate is different, so that it can be copied or cannot be copied. In this case, even content downloaded on a recordable DVD using a network can be copied to another recordable DVD.

  In the present embodiment, the content certificate recorded on the DVD medium is different from those in the first and second embodiments. FIG. 10 is a data structure diagram of a content certificate according to the third embodiment.

  As in the first embodiment, the data structure of the content certificate of the present embodiment follows the header, the certificate type, the content sequence number for uniquely identifying the content, the content revocation list, the content hash value, Includes a signature. Here, the content sequence number, content revocation list, content hash value, and signature are registered in the same manner as the content certificate of the first embodiment.

  In the present embodiment, the content type is registered in the certificate type. That is, as shown in FIG. 10, in the certificate type field, three types are defined: content on a DVD-ROM, copy content on a recordable DVD, or download content on a recordable DVD. Yes. Here, the copy content on the recordable DVD means content recorded on the recordable DVD by copy processing, and the download content on the recordable DVD is downloaded via the network and recorded on the recordable DVD. Is meant to be content.

  In the example of FIG. 10, the content on the DVD-ROM is shown when the certificate type is “0”, the copy content on the recordable DVD is shown when “1”, and the recordable DVD is shown when “2”. The download content above is shown. However, such a value is an example and is not limited to these.

  The functional configuration of the DVD recorder according to the present embodiment is the same as that of the DVD recorder 700 of the second embodiment shown in FIG. In FIG. 7, a recordable DVD 172 is a recordable recordable DVD on which the downloaded content is recorded, and this content is further copied to another recordable DVD on the record destination (copy destination, move destination) Assume that you want to move. Here, the recording type DVD of the recording source is shown with a symbol “recording type DVD 172”, and the recording type recording type DVD is indicated as “recording destination recording type DVD” or “copying destination recording type DVD” or “ It is shown as “recordable DVD of move destination”.

  In the copy / move request unit 743 of the DVD recorder 700 according to the present embodiment, the certificate type of the content certificate requested to the copy permission server 200 or the move permission server 400 is the recording source DVD medium and the content type. Depending on the DVD medium of the recording destination and the action (copy / move), the type is determined.

  FIG. 11 is an explanatory diagram showing a recording source DVD medium and content type, a recording destination DVD medium, an action (instructed by a copy / move user), and a certificate type of a requested content certificate.

  As shown in FIG. 11, when the content on the DVD-ROM 171 is copied to the recording DVD of the recording destination, when the copy content of the data storage unit 701 is moved to the recording DVD 172, the download content of the data storage unit 701 is recorded In the case of copying to a type DVD 172, when the download content on the recording type DVD 172 is copied to another recording type DVD, the certificate type requests a content certificate of the copy content.

  Further, when the download content on the data storage unit 701 is moved to the recording DVD of the recording destination, or the download content on the recording DVD 172 is moved to another recording DVD of the recording destination, the certificate type is downloaded. You will be requesting a content certificate for the content.

  Further, in other cases, that is, when the content on the DVD-ROM 171 is copied to the data storage unit 701, or when the download content on the recordable DVD 172 is copied or moved to the data storage unit 701, the content certificate No request is made.

  Next, the copy process according to the present embodiment configured as described above will be described. First, the user instructs the operation unit (not shown) to copy or move content to the DVD recorder 700. For example, when copying the content (downloaded content) on the downloaded recordable DVD 172, the user issues a copy instruction from the operation unit (not shown). The DVD recorder 700 receives the user's copy instruction and executes the following copy process.

  Check whether the media type and the content certificate type are valid combinations. If the media type is DVD-ROM, the copy process is interrupted if the content type is not a DVD-ROM content certificate. In the case of a recordable DVD, if it is not a content certificate for download content, copy processing is interrupted and error processing is performed. On the other hand, if the combination is valid, the signature verification process of the content certificate is performed. If the verification is successful, the content certificate requested to the copy permission server 200 is changed by the copy destination. That is, in the case where the data storage unit 701 is the copy destination, no content certificate is required. When the copy destination is a recordable DVD, a content certificate for copy content is requested. More specific description will be given below.

  12 and 13 are flowcharts showing the procedure of the copy process according to the third embodiment. When a copy instruction is received from the user, first, the recording medium determination unit 162 checks the media type of the copy source DVD medium (step S91). When the media type is a recordable DVD, the certificate verification unit 163 further determines whether the content certificate is for download, that is, whether the downloaded content on the recordable DVD is registered in the certificate type. (Step S94). If the download content on the recordable DVD is not registered in the certificate type (step S94: No), error processing is performed (step S96), and the copy processing is stopped.

  On the other hand, if the content certificate is for download in step S94, that is, if the downloaded content on the recordable DVD is registered in the certificate type (step S94: Yes), the signature verification unit 161 causes the key to be downloaded. The signature of the content certificate is verified using the public key stored in the storage unit 167 (step S93).

  If the copy source media type is DVD-ROM in step S91, the certificate verification unit 163 further registers whether the content certificate is for DVD-ROM, that is, the DVD-ROM is registered in the certificate type. It is checked whether or not (step S92).

  If the DVD-ROM is not registered in the certificate type (step S92: No), error processing is performed (step S96), and the copy processing is stopped.

  On the other hand, if the content certificate is for DVD-ROM in step S92, that is, if the DVD-ROM is registered in the certificate type (step S92: Yes), the signature verification unit 161 performs the key storage unit. The signature of the content certificate is verified using the public key stored in 167 (step S93).

  If verification of the content certificate signature in step S93 fails (step S95: No), error processing is performed (step S96), and the copy processing is stopped.

  On the other hand, if the verification of the content certificate signature is successful (step S95: Yes), the copy destination is checked (step S97).

  If the copy destination is the data storage unit 701, the copy / move request unit 743 transmits a copy permission request message to the copy permission server 200 (step S98).

  The copy permission server 200 authenticates the DVD recorder 700. If an authentication result failure is received (step S99: No), an error process is performed because the DVD recorder 700 is invalid (step S106), and the copy process is stopped.

  On the other hand, when the authentication result success is received from the copy permission server 200 (step S99: Yes), the recording unit 113 records the content in the data storage unit 701 in the DVD recorder 700 (step S100). As a result, the content of the DVD-ROM or the download content of the recordable DVD is legitimately copied to the data storage unit 701.

  As shown in FIG. 11, in this case, that is, when the copy destination is the data storage unit 701, the request for the content certificate is not performed.

  If the copy destination is a recordable DVD in step S97, the copy / move request unit 743 transmits a copy permission request message to the copy permission server 200 (step S101). At this time, a message indicating whether the copy source medium is a recordable DVD or a DVD-ROM may be inserted into the copy permission server 200.

  When the copy permission server 200 authenticates the DVD recorder 700 and receives an authentication result failure (step S102: No), an error process is performed because the DVD recorder 700 is invalid (step S106), and the copy process is performed. Discontinue.

On the other hand, when a successful authentication result is received from the copy permission server 200 (step S102: Yes), the copy move request unit 743 sends a copy permission request message and a copy destination recording type DVD to the copy permission server 200. The media ID is transmitted (step S103). In this case, since the copy destination is a recordable DVD and the copy source is a DVD-ROM or a recordable DVD and is a download content, the certificate type requests a content certificate of the copy content according to FIG.
In order to receive this content certificate, it is necessary to notify the copy permission server 200 of what hash value the signature is given to, but the content recorded on the copy source medium When the certificate transmission method (fourth method in the first embodiment) is adopted, the copy permission server 200 side checks the consistency between the certificate type of the content certificate and the media type of the copy source medium. If the processing for verifying the signature of the content certificate is performed, the above processing (steps S92 to S93) is not necessarily performed by the DVD recorder 700. In this case, the signature verification unit 161 and the certificate verification unit 163 are not necessarily required in the host unit.

  As a result, the content certificate for copy content (certificate type is copy content), MKB, and TKF are transmitted from the copy permission server 200, and are received by the certificate receiving unit 142 (step S104).

  Then, the recording unit 113 copies the content by recording it on the recording type recording DVD (step S105). At this time, the content certificate for copy content (certificate type is copy content), MKB, and TKF received from the copy permission server 200 are also recorded on the recordable DVD. As a result, the content of the DVD-ROM or the download content of the recording type recording DVD 172 is legitimately copied to the recording type recording DVD.

  Next, the move process according to the third embodiment will be described. For example, when moving the content recorded on the recordable DVD 172 or the data storage unit 701, the user gives a move instruction from an operation unit (not shown). The DVD recorder 700 receives the user's move instruction and executes the move process.

  That is, the validity of the combination of the move source and the content certificate is checked, and if the move source is content recorded in the data storage unit 701, the content certificate does not need to be verified, and any content recorded on the recordable DVD 172 may be used. For example, it is determined whether the content certificate is for download or copy content. If the combination is valid, signature verification processing of the content certificate is performed. If the verification is successful, the content certificate requested to the move permission server 400 is changed by the move destination. More specific description will be given below.

  14 and 15 are flowcharts showing the procedure of the move process according to the third embodiment. When a move instruction is received from the user, the recording medium determination unit 162 first checks the media type of the copy source DVD medium (step S111). If the media type is DVD-ROM, the move process cannot be performed, so an error process is performed (step S119), and the move process is stopped.

  On the other hand, if the move source is the data storage unit 701 in step S111, the copy / move request unit 743 transmits a move permission request message to the move permission server 400 (step S112).

  When the move permission server 400 authenticates the DVD recorder 700 and receives an authentication result failure (step S113: No), an error process is performed because the DVD recorder 700 is invalid (step S119), and the move process is performed. Discontinue.

  On the other hand, when the authentication result success message is received from the move permission server 400 (step S113: Yes), the content certificate recorded on the recordable DVD that is the move destination is for download (certificate type). Is a download content on a recordable DVD) or a copy content (the certificate type is a copy content on a recordable DVD) (step S114).

  If the content certificate is for download (the certificate type is the download content on the recordable DVD), the copy / move request unit 743 sends a request message for the content certificate for download to the move permission server 400. The media ID of the recordable DVD of the move destination is transmitted (step S115).

  On the other hand, if the content certificate is for copy content (the certificate type is copy content on a recordable DVD), the copy / move request unit 743 requests the move permission server 400 to request a content certificate for copy content. The message and the media ID of the recordable DVD of the move destination are transmitted (step S116).

  As a result, the content certificate, MKB, and TKF are transmitted from the move permission server 400, and are received by the certificate receiving unit 142 (step S117). Then, the recording unit 113 records the contents of the data storage unit 701 on the recording type recording DVD (step S118). At this time, if the contents of the data storage unit 701 are managed by the TKF as described in the second embodiment (first copying method), the TKF of the data storage unit 701 is deleted. On the other hand, when the content of the data storage unit 701 does not use TKF and the content itself is bound to the DVD recorder 700 (second copying method), the content of the data storage unit 701 is deleted. Thereafter, the content certificate, MKB, and TKF received from the move permission server 400 are also recorded on the recordable DVD. As a result, the contents of the data storage unit 701 are legitimately moved to the recordable DVD.

  Returning to step S111, if the move source is a recordable DVD, the content certificate recorded on the recordable DVD 172 that is the move source is for download (the certificate type is the download content on the recordable DVD) or a copy. It is checked whether the content is used (the certificate type is copy content on the recordable DVD) (step S120).

  If the content certificate is neither for download nor for copy content (step S120: No), error processing is performed (step S127), and the move processing is stopped.

  On the other hand, if the content certificate is for download or copy content (step S120: Yes), the content certificate is used by the signature verification unit 161 using the public key stored in the key storage unit 167. Is verified (step S121). If verification of the content certificate signature fails (step S122: No), error processing is performed (step S127), and the move processing is stopped.

  On the other hand, if the signature verification of the content certificate is successful in step S122 (step S122: Yes), the move destination is checked (step S123).

  If the move destination is a recordable recording type DVD, the processing from step S112 to S119 described above is performed. On the other hand, when the move destination is the data storage unit 701, the copy / move request unit 743 transmits a move permission request message to the move permission server 400 (step S124).

  When the move permission server 400 authenticates the DVD recorder 700 and receives an authentication result failure (step S125: No), an error process is performed because the DVD recorder 700 is invalid (step S127), and the copy process is performed. Discontinue.

  On the other hand, when the authentication result success is received from the move permission server 400 (step S125: Yes), the recording unit 113 records the content in the data storage unit 701 in the DVD recorder 700 (step S126). At this time, the TKF recorded on the recordable recording type DVD 172 is deleted. As a result, the downloadable content or copy content of the recordable DVD 172 is legitimately moved to the data storage unit 701.

  It should be noted that the reproduction processing of the downloaded content or copy content copied or moved to the recording DVD of the recording destination is performed in the same manner as the reproduction processing in the first embodiment described with reference to FIGS. However, in the present embodiment, the content certificate and media consistency verification processing in step S32 is different from that in the first embodiment.

  That is, in this embodiment, when verifying the certificate type of the content certificate recorded on the recordable DVD, it is checked whether it is copy content or download content. This will be specifically described below.

  FIG. 16 is a flowchart illustrating the procedure of the content certificate / media consistency verification process according to the third embodiment. First, the media type is acquired from the DVD medium, and the media type is checked (step S131). If the media type is DVD-ROM, the value of the certificate type field of the content certificate is acquired and verified (step S132), and it is checked whether it is a DVD-ROM (step S133). If it is not a DVD-ROM (step S133: No), it is determined that the combination is not valid with the media type, and a verification failure is returned as a return value (step S139). On the other hand, if the certificate type is DMD-ROM (step S133: Yes), the signature of the content certificate is verified (step S134). If the verification result is a verification success (step S135: Yes), The verification success is returned as a return value (step S136). On the other hand, when the verification result is a verification failure (step S135: No), the verification failure is returned as a return value (step S139).

  Returning to step S131, if the media type is a recordable DVD, the value of the certificate type field of the content certificate is acquired and verified (step S137), and it is checked whether it is copy content or download content. (Step S138). If it is neither copy content nor download content (step S138: No), it is determined that the combination is not valid with the media type, and a verification failure is returned as a return value (step S139). On the other hand, when the certificate type is either copy content or download content (step S138: Yes), signature verification of the content certificate from step S134 to S136 is performed.

  As described above, in the DVD recorder 700 according to the third embodiment, the three types of certificate types of the content certificate are defined as DVD-ROM, copy content, and download content, and the media type and content certificate of the copy source or move source are defined. It is determined whether or not the combination with the certificate type is valid. If the combination is valid, a content certificate having a different certificate type depending on the content of the recording source, the recording destination, and whether the copy or move is used. It is received from the move permission server 400 and recorded together with the content on the recording destination DVD medium. As a result, according to the DVD recorder 700 according to the third embodiment, even downloaded content can be handled in the same way as package media such as DVD-ROM, so that unauthorized copying and unauthorized movement of content can be ensured. The copyright of the content can be protected. In addition, the physical distribution cost of DVD media can be reduced for content manufacturers.

  In the DVD recorder according to the first to third embodiments, as shown in FIGS. 1 and 7, the copy management units 140 and 740 perform copy or move processing, and the playback processing unit 150 performs content playback processing. Although it is configured, it is not limited to this. That is, a reproduction-only device can be used to reproduce the content. In this case, a reproduction-only device (for example, a DVD player) includes a drive 110 and host units 120 and 720. The reproduction processing unit 150, the signature verification unit 161, and the key storage unit 167 described above are included in the host units 120 and 720. It is good also as a structure provided only with.

  In the DVD recorder according to the first to third embodiments, the DVD medium is described as a recording medium. However, the present invention is not limited to the DVD medium, and the present invention can be applied to any recording medium.

  In the second and third embodiments, the copy permission server 200 and the move permission server 400 are separately provided. However, a single server can be used as long as the server has both functions. is there.

  Note that the copy processing program, the move processing program, and the reproduction processing program executed by the DVD recorder according to the first to third embodiments are provided by being incorporated in advance in a ROM or the like.

  The copy processing program, the move processing program, and the playback processing program executed by the DVD recorder according to the first to third embodiments are files in an installable format or an executable format, such as a CD-ROM, a flexible disk (FD), and a CD. The recording medium may be provided by being recorded on a computer-readable recording medium such as -R or DVD (Digital Versatile Disk).

  Further, the copy processing program, the move processing program, and the reproduction processing program executed by the DVD recorder according to the first to third embodiments are stored on a computer connected to a network such as the Internet and downloaded via the network. You may comprise so that it may provide. The copy processing program, the move processing program, and the playback processing program executed by the DVD recorder according to the first to third embodiments may be provided or distributed via a network such as the Internet.

  The copy processing program, the move processing program, and the reproduction processing program executed by the DVD recorder according to the first to third embodiments include the above-described units (reading unit 112, recording unit 113, copy management unit 140, reproduction processing unit 150, signature). The module configuration includes a verification unit 161, a recording medium determination unit 162, a certificate verification unit 163, a communication processing unit 164, and the like. As actual hardware, a CPU (processor) copies from the ROM to a copy processing program, moves By reading and executing the processing program and the reproduction processing program, the above-described units are loaded onto the main storage device, and the reading unit 112, the recording unit 113, the copy management unit 140, the reproduction processing unit 150, the signature verification unit 161, and the recording medium determination Section 162, certificate verification section 163, communication processing section 164, etc. It is generated on the device.

  It should be noted that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

100, 700 DVD recorder 112 Reading unit 113 Recording unit 120, 720 Host unit 140 Copy management unit 140, 740 Copy management unit 142 Certificate receiving unit 151 Content playback unit 153 Binding determination unit 155 Cryptographic processing unit 161 Signature verification unit 163 Certificate Verification unit 167 Key storage unit 171 DVD-ROM
172 recordable DVD
200 copy permission server 400 move permission server 701 data storage unit 743 copy / move request unit

Claims (6)

A content playback device for playing back content recorded on a recording medium and encrypted with a first encryption key,
A playback unit that decrypts the content using the first encryption key and plays back the decrypted content;
A certificate type in which a content type indicating a type of recording of the content on the recording medium is registered, a hash value based on partial information of the content, and a second value for the certificate type and the hash value. It is verified whether or not a content certificate including a signature generated by an encryption key exists on the recording medium, and the content certificate recorded on the recording medium when the content certificate exists on the recording medium A certificate verification unit that determines whether the certificate type of the certificate and the type of the recording medium are a valid combination;
A hash value that verifies whether or not the hash value included in the content certificate matches the hash value calculated from the content when the certificate type and the recording medium type are a valid combination A verification unit;
A digital watermark verification unit that determines whether or not a digital watermark is embedded in the content during reproduction of the content when the content certificate does not exist in the recording medium,
When the hash value included in the content certificate matches the hash value calculated from the content, the playback unit continues to play the content, and the certificate type and the recording medium type Is not a valid combination, or if the hash value included in the content certificate does not match the hash value calculated from the content, or if a digital watermark is embedded in the content, Stop playing the content,
A content reproduction apparatus characterized by the above. A signature verification unit that verifies the signature with a public key corresponding to the second encryption key when the certificate type and the recording medium type are a valid combination;
If the verification of the signature is successful, starting playback of the content;
The content reproduction apparatus according to claim 1. The content certificate further includes a content sequence number for specifying the content and a content revocation list in which content sequence numbers of illegally created content are registered,
The certificate verification unit further determines that the content sequence number of the content certificate is the content revocation list of the content certificate when the certificate type and the recording medium type are a valid combination. And whether it exists in
If the content sequence number of the content certificate does not exist in the content revocation list of the content certificate, the playback unit starts playback of the content, and the content sequence number of the content certificate Is present in the content revocation list of the content certificate, canceling playback of the content;
The content reproduction apparatus according to claim 1 or 2, wherein When the certificate type and the recording medium type are a valid combination, the bind information calculated based on the media ID unique to the recording medium and the content certificate or the first encryption key, and the network A bind determination unit that determines whether or not the bind information received from the copy permission server connected to
The playback unit starts playback of the content when the calculated bind information matches the received bind information, and when the calculated bind information does not match the received bind information , Stop playing the content,
The content reproduction apparatus according to claim 1, wherein A content reproduction method executed by a content reproduction apparatus for reproducing content recorded on a recording medium and encrypted with a first encryption key,
A reproducing step of decrypting the content using the first encryption key and reproducing the decrypted content;
A certificate type in which a content type indicating a type of recording of the content on the recording medium is registered, a hash value based on partial information of the content, and a second value for the certificate type and the hash value. It is verified whether or not a content certificate including a signature generated by an encryption key exists on the recording medium, and the content certificate recorded on the recording medium when the content certificate exists on the recording medium A certificate verification step for determining whether the certificate type of the certificate and the type of the recording medium are a valid combination;
A hash value that verifies whether or not the hash value included in the content certificate matches the hash value calculated from the content when the certificate type and the recording medium type are a valid combination A verification step;
A digital watermark verification step of determining whether or not a digital watermark is embedded in the content during reproduction of the content when the content certificate does not exist in the recording medium,
In the reproduction step, when the hash value included in the content certificate matches the hash value calculated from the content, the reproduction is continued, and the certificate type and the recording medium type are Is not a valid combination, or if the hash value included in the content certificate does not match the hash value calculated from the content, or if a digital watermark is embedded in the content, Stop playing the content,
A content reproduction method characterized by the above. A program for causing a computer to play back content recorded on a recording medium and encrypted with a first encryption key,
A reproducing step of decrypting the content using the first encryption key and reproducing the decrypted content;
A certificate type in which a content type indicating a type of recording of the content on the recording medium is registered, a hash value based on partial information of the content, and a second value for the certificate type and the hash value. It is verified whether or not a content certificate including a signature generated by an encryption key exists on the recording medium, and the content certificate recorded on the recording medium when the content certificate exists on the recording medium A certificate verification step for determining whether the certificate type of the certificate and the type of the recording medium are a valid combination;
A hash value that verifies whether or not the hash value included in the content certificate matches the hash value calculated from the content when the certificate type and the recording medium type are a valid combination A verification step;
A digital watermark verification step for determining whether a digital watermark is embedded in the content during playback of the content when the content certificate does not exist in the recording medium;
In the reproduction step, when the hash value included in the content certificate matches the hash value calculated from the content, the reproduction is continued, and the certificate type and the recording medium type are Is not a valid combination, or if the hash value included in the content certificate does not match the hash value calculated from the content, or if a digital watermark is embedded in the content, Stop playing the content,
A program characterized by

Images