WO2011111370A1 - 記録システム、再生システム、鍵配信サーバ、記録装置、記録媒体装置、再生装置、記録方法、及び、再生方法 - Google Patents
記録システム、再生システム、鍵配信サーバ、記録装置、記録媒体装置、再生装置、記録方法、及び、再生方法 Download PDFInfo
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- WO2011111370A1 WO2011111370A1 PCT/JP2011/001340 JP2011001340W WO2011111370A1 WO 2011111370 A1 WO2011111370 A1 WO 2011111370A1 JP 2011001340 W JP2011001340 W JP 2011001340W WO 2011111370 A1 WO2011111370 A1 WO 2011111370A1
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- 238000006243 chemical reaction Methods 0.000 description 21
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
- G06F21/10—Protecting distributed programs or content, e.g. vending or licensing of copyrighted material ; Digital rights management [DRM]
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- the present invention relates to a technique for preventing unauthorized use of digital content.
- Digital content which is a digital work such as a movie or music, is digitally distributed to a recording device via a network, recorded on a recording medium using the recording device, and the content recorded on the recording medium is reproduced by a playback device.
- Digital content distribution services such as playback are becoming popular.
- specific examples of the recording device are a KIOSK terminal, a personal computer, and the like
- specific examples of the recording medium are a recordable DVD (Digital Versatile Disk), a recordable BD (Blu-ray Disk), a memory card, and the like.
- Specific examples of the playback device are a music player, a video display portable terminal, and the like.
- Non-Patent Document 1 -The recording medium stores a unique medium ID that is unique to the recording medium and cannot be rewritten, Store the signature verification public key and the device key unique to the playback device in the playback device, A content distribution server stores a media key and an encrypted media key block (Media Key Block (MKB)), where the encrypted media key block uses a device key stored in each playback device.
- MKB Media Key Block
- Encrypted media key configured to include encrypted media key
- Content distribution server generates a unique title key for each content, and encrypts content using the title key to generate encrypted content And encrypting the title key using the media key to generate an encrypted title key
- the content distribution server performs billing processing in response to a content purchase request from the user, and then uses the signature generation private key corresponding to the signature generation public key for the media ID of the user's recording medium.
- the user recording device stores the received media ID signature, the encrypted media key block, the encrypted title key, and the encrypted content on the recording medium
- the user's playback device verifies the signature of the media ID using the signature verification public key and the media ID of the recording medium. If the verification is successful, the playback device uses the stored device key from the recording medium. Decrypting the encrypted media key included in the read encrypted media key block, decrypting the encrypted title key using the decrypted media key, decrypting the encrypted content using the decrypted title key, Play back the decrypted content.
- a media ID signature, an encrypted media key block, an encrypted title key, and an encrypted content recorded on a regular recording medium are copied to another unauthorized recording medium, Even if the encrypted content is to be decrypted, the media ID of the legitimate recording medium cannot be copied to an unauthorized recording medium, so the media ID of the legitimate recording medium cannot be obtained from the other recording medium, and the signature of the media ID is verified. Fail. As a result, the encrypted content cannot be decrypted correctly.
- this content decryption tool uses an embedded media key by inputting an encrypted media key block, an encrypted title key corresponding to various contents (titles), and an encrypted content, Decrypt the encrypted media key included in the encrypted media key block, decrypt the encrypted title key using the decrypted media key, decrypt the encrypted content using the decrypted title key, and decrypt This is a tool for outputting content, and the decrypted content can be freely and illegally copied after being output.
- the encrypted media key block is updated, and the encrypted content (strictly speaking, the encrypted media key block is distributed after the update by the unauthorized content decryption tool).
- Encrypted content can be prevented from being decrypted. That is, Store the updated media key and the updated encrypted media key block (Media Key Block (MKB)) in the content distribution server.
- MKB Media Key Block
- the updated encrypted media key block is generated by the following procedure.
- An encrypted media is generated by generating an updated media key and encrypting the updated media key using each of the device keys stored in other regular playback devices excluding the specified device key. Generate a key and generate an updated encrypted media key block that includes the generated encrypted media key. In this way, by generating an updated encrypted media key block, even if it is attempted to decrypt the updated encrypted media key block with the device key incorporated in the content decryption tool, the correct updated media key is obtained. Cannot be generated.
- the content distribution server encrypts the title key with the updated media key, generates an updated encrypted title key,
- the content distribution server performs billing processing in response to a content purchase request from the user, and then signs the media ID of the user's recording medium, the updated encrypted media key block, and the updated encrypted title The key and the encrypted content are distributed to the user.
- the device key incorporated in the content decryption tool cannot decrypt the encrypted media key included in the updated encrypted media key block, it cannot be decrypted. Cannot decrypt encrypted content. Therefore, according to this technology, by updating the encrypted media key block, decryption of the encrypted content (strictly, the encrypted content distributed after updating the encrypted media key block) by an unauthorized content decryption tool. Can be prevented.
- a malicious user illegally obtains a device key stored in an authorized playback device, decrypts the encrypted title key using the obtained device key, and uses the web server to decrypt the decrypted title key.
- an attack that illegally sells a content decryption tool that obtains a publicly available title key and decrypts encrypted content Assume an attack that illegally sells a content decryption tool that obtains a publicly available title key and decrypts encrypted content.
- the content decryption tool obtains the corresponding title key from the Web server by inputting the encrypted title key and the encrypted content corresponding to various contents (titles), and uses the obtained title key.
- the decrypted content can be freely and illegally copied after being output.
- the content decryption tool does not include a device that has been illegally obtained by a malicious user, and therefore cannot identify a device key that has been illegally obtained by a malicious user. For this reason, it is impossible to prevent the decryption of the encrypted content by the content decryption tool by updating the encrypted media key block described above.
- the conventional technology has a problem in that the rights of the copyright holder of digital contents cannot be protected against this attack.
- the distribution server generates a different title key for each distribution on demand, encrypts the content with a different title key for each distribution, and generates different encrypted contents for each distribution
- a media key to encrypt a different title key for each distribution, generate a different encrypted title key for each distribution, and distribute different encrypted contents and encrypted title keys for each distribution.
- An object of the present invention is to provide a recording / reproducing system, a recording / reproducing apparatus, a recording medium apparatus, and a recording / reproducing method capable of preventing the above-mentioned attack by a malicious user in order to solve the above problems. To do.
- a recording medium device controls recording of first encrypted content that is transmitted by a key distribution server and encrypted using a first title key.
- a recording medium device used together with a recording device for performing storage, receiving means for receiving an encrypted first title key from the key distribution server, and the encrypted first title key Decrypting means for decrypting and outputting to the recording apparatus, a title key generating means for generating a second title key serving as a different key for each content recording, and outputting to the recording apparatus, and the recording Acquiring from the device the second encrypted content generated by decrypting the first encrypted content with the first title key and encrypting with the second title key, and storing it in the storage means And a stage.
- the recording medium device has the above-described configuration, whereby the first encrypted content is once decrypted with the first title key, and a second title key that is different for each recording process is obtained. And encrypted as a second encrypted content. Therefore, even if a title key distribution attack is performed in which the first title key, which is a key for decrypting the first encrypted content, is disclosed to a malicious user and released, the second title stored in the recording medium device is stored. Since the encrypted content cannot be decrypted with the published first title key, it is possible to prevent the content from being illegally used.
- Embodiment 1 is an overall configuration diagram of a recording / reproducing system in Embodiment 1 of the present invention.
- Detailed configuration diagram of key issuing authority in Embodiment 1 of the present invention The detailed block diagram of the key distribution server in Embodiment 1 of this invention 1 is a detailed configuration diagram of a recording apparatus according to Embodiment 1 of the present invention.
- a recording medium device is a recording medium device that is used together with a recording device that performs recording control of a first encrypted content that is transmitted by a key distribution server and encrypted using the first title key.
- a medium device a storage means, a receiving means for receiving an encrypted first title key from the key distribution server, and decrypting the encrypted first title key, to the recording device From the decryption means for output, the second title key that is a different key for each recording of the content, the title key generation means for output to the recording device, and the first encryption from the recording device
- the encryption of the first title key is performed using a controller individual key unique to the recording medium device that is shared between the key distribution server and the recording medium device
- the storage medium device may include holding means for holding the controller individual key, and the decryption means may decrypt the encrypted first title key using the controller individual key.
- the key distribution server encrypts the first title key with the controller individual key unique to the recording medium device. Can be delivered. That is, the first title key can be distributed in a mode that can be decrypted only by the recording medium device.
- the recording medium device further includes an encryption unit that encrypts the second title key with the controller individual key and stores the encrypted second title key in the storage unit, and is used together with the content reproduction device. Obtains the controller individual key, the encrypted second title key, and the content encrypted by the second title key from the recording medium device, and the controller individual key.
- a reproducing means for reproducing the decrypted content.
- the content that is encrypted and distributed with the first title key is restricted so that it cannot be decrypted with the first title key in the playback device, and is held so that it can be decrypted with the second title key. be able to.
- the recording medium device further includes authentication means for mutual authentication with the recording device, and the decryption means decrypts the encrypted first title key only when the mutual authentication is successful. It is good as well.
- the key distribution server does not transmit the first title key encrypted with the unauthorized media key, and the encryption unit received by the receiving unit
- the converted first title key may be a first title key encrypted with a non-invalid controller individual key.
- the title key generation means may generate a random number as the second title key.
- the second title key can be randomly generated.
- the content may be a part of the entire content held by the key distribution server.
- the recording medium device may be accommodated in a housing of the recording device.
- the recording medium device can be configured in a manner built in the recording device.
- a recording method is a recording method used for a recording medium device, and the recording medium device is encrypted by using a first title key transmitted by a key distribution server.
- the recording method is used together with a recording device that performs recording control of the first encrypted content.
- the recording method includes a reception step of receiving an encrypted first title key from the key distribution server; and the encrypted first title key.
- the second encrypted content generated by decrypting the first encrypted content with the first title key and encrypting with the second title key is acquired from the recording device and recorded. Including an acquisition step of storing in the storage means medium apparatus.
- a recording medium is a computer-readable recording medium that stores a recording program used in a recording medium device, and the recording medium device is transmitted by a key distribution server. Used in conjunction with a recording device that controls recording of the first encrypted content encrypted using the title key, and the recording program receives the first title key encrypted from the key distribution server. Decrypting the encrypted first title key and outputting it to the recording device; generating a second title key that is a different key for each content recording; Generating a title key to be output to a recording device; and decrypting the first encrypted content from the recording device with the first title key and encrypting with the second title key. It turned into acquires the second encrypted content generated by including an acquisition step of storing in a storage means included in the recording medium device.
- An integrated circuit is an integrated circuit used in a recording medium device, and the recording medium device is encrypted by using a first title key transmitted by a key distribution server.
- the integrated circuit is used together with a recording device that performs recording control of the first encrypted content.
- the integrated circuit includes a storage unit, a receiving unit that receives an encrypted first title key from the key distribution server, and the encryption unit.
- the decrypted first title key is decrypted and output to the recording device, and the second title key that is different for each content recording is generated and output to the recording device
- a second encrypted content generated by decrypting the first encrypted content with the first title key and encrypting with the second title key is obtained from a title key generating means and the recording device. Before It comprises obtaining means to be stored in the storage means.
- the first encrypted content is once decrypted with the first title key, and further encrypted with the different second title key for each recording process, and recorded as the second encrypted content. To do. Therefore, even if a title key distribution attack is performed in which the first title key, which is a key for decrypting the first encrypted content, is disclosed to a malicious user and released, the second title stored in the recording medium device is stored. Since the encrypted content cannot be decrypted with the published first title key, it is possible to prevent the content from being illegally used.
- a recording apparatus is a recording apparatus that records a first encrypted content that is transmitted by a key distribution server and is encrypted using a first title key.
- Receiving means for receiving an encrypted first title key from the key distribution server, first decrypting means for decrypting the encrypted first title key, and each time content is recorded
- Title key generation means for generating a second title key that is a different key
- second decryption means for decrypting the first encrypted content with the first title key
- decryption by the second decryption means Encryption means for encrypting the content with the second title key to generate second encrypted content and storing the encrypted content in the storage means.
- the first encrypted content is once decrypted with the first title key, and further encrypted with the different second title key for each recording process, and recorded as the second encrypted content. To do. Therefore, even if a title key distribution attack is performed in which the first title key, which is a key for decrypting the first encrypted content, is disclosed to the malicious user and released, the second title stored in the recording device is stored. Since the encrypted content cannot be decrypted with the published first title key, it is possible to prevent the content from being illegally used.
- a key distribution server is a key distribution server used together with a recording medium device and a recording device that receives content and writes the content to the recording medium device, and holds a first title key Holding means; content holding means for holding the content; content encryption means for encrypting the content with the first title key and transmitting it to the recording device; and encrypting the first title key for the recording Title key encryption means for transmitting to the device, and a title key generation means for generating a second title key that is a different key for each distribution of content and outputting it to the recording device,
- the recording device acquires the content encrypted with the first title key, the first title key, and the second title key
- the recording device encrypts the content. Decoded by the first title key content, the content decoded encrypted with the second title key is written into the recording medium device.
- the first encrypted content is once decrypted with the first title key, and further encrypted with the second title key that is different for each recording process, and the second encrypted content is used as the second encrypted content. It is recorded on the recording medium device. Therefore, even if a title key distribution attack is performed in which the first title key, which is a key for decrypting the first encrypted content, is disclosed to a malicious user and released, the second title stored in the recording medium device is stored. Since the encrypted content cannot be decrypted with the published first title key, it is possible to prevent the content from being illegally used.
- the key distribution server further includes a holding unit that holds a controller individual key that is shared with the recording medium device and that is unique to the recording medium device, and the title key encryption unit includes: Only when the controller individual key is not an illegal key, the first title key may be encrypted using the controller individual key as the encryption of the first title key.
- the key distribution server shares the media key unique to the recording medium device, the first title key can be encrypted and distributed with the controller individual key unique to the recording medium device. That is, the first title key can be distributed in a mode that can be decrypted only by the recording medium device.
- the recording medium device further acquires the second title key from the recording device and holds the second title key encrypted with the controller individual key
- the key distribution server is further used together with the content reproduction device.
- the content reproduction device acquires the controller individual key, the encrypted second title key, and the content encrypted with the second title key from the recording medium device; , A title key decrypting unit for decrypting the encrypted second title key using the controller individual key, and a content encrypted by the second title key using the second title key. It is good also as providing the content decoding means to decode and the reproduction
- the content that is encrypted and distributed with the first title key is restricted so that it cannot be decrypted with the first title key in the playback device, and is held so that it can be decrypted with the second title key. Can do.
- the key distribution server further includes authentication means for mutual authentication with the recording device, and the output of the second title key by the title key generation means to the recording device is successful in the mutual authentication. It is good also as being permitted only to.
- the title key generation means may generate a random number as the second title key.
- the second title key can be randomly generated.
- a key distribution method is a key distribution method used for a key distribution server, wherein the key distribution server receives a recording medium device and writes content into the recording medium device.
- the key distribution method includes a key holding step for holding a first title key, a content holding step for holding the content, and the content is encrypted with the first title key and transmitted to the recording device.
- a recording medium is a computer-readable recording medium that stores a key distribution program used for a key distribution server, and the key distribution server receives content from a recording medium device.
- the key distribution program is used together with a recording device for writing to the recording medium device, and the key distribution program includes a key holding step for holding a first title key, a content holding step for holding the content, and the content as the first title key.
- the content encryption step for encrypting and transmitting to the recording device the title key encryption step for encrypting the first title key and transmitting to the recording device, and a different key for each content distribution
- a title key generating step of generating a second title key and outputting it to the recording device When the content encrypted with the first title key, the first title key, and the second title key are acquired, the encrypted content is stored in the first title key.
- the decrypted content is encrypted with the second title key and written to the recording medium device.
- the first encrypted content is once decrypted with the first title key, and further encrypted with the different second title key for each recording process, and recorded as the second encrypted content. Is done. Therefore, even if a title key distribution attack is performed in which the first title key, which is a key for decrypting the first encrypted content, is disclosed to a malicious user and released, the second title stored in the recording medium device is stored. Since the encrypted content cannot be decrypted with the published first title key, it is possible to prevent the content from being illegally used.
- FIG. 1 is a diagram showing an overall configuration of a recording / reproducing system according to Embodiment 1 of the present invention.
- the recording / reproducing system includes a key distribution server 100, a recording device 200, a recording medium device 300, a reproducing device 400, and a key issuing station 900.
- a case where the recording medium device 300 is a memory card will be described.
- FIGS. 2 to 6 show detailed configurations of the key issuing station 900, the key distribution server 100, the recording device 200, the memory card 300, and the playback device 400 that constitute the recording / playback system, respectively.
- the key issuing authority 900 includes a root public key generating unit 901, a controller ID storage unit 902, a partial media ID generating unit 903, and a recording medium device public key generating unit. 904, media unique key generation unit 905, recording medium device secret key generation unit 906, device identification information generation unit 907, recording device / playback device / key distribution server public key generation unit 908, recording device / playback device / key distribution server secret Key generation unit 909, root secret key generation unit 910, recording medium device public key certificate generation unit 911, controller key storage unit 912, encryption unit 913, recording device / playback device / key distribution server public key certificate generation unit 914 Consists of.
- the root public key generation unit 901 and the root secret key storage unit 910 generate a root public key of the key issuing station and a root secret key corresponding to the root public key.
- the root public key is notified from the key issuing authority to the recording apparatus manufacturer apparatus, the recording medium apparatus manufacturer apparatus, and the reproducing apparatus manufacturer apparatus, and the recording apparatus, recording medium apparatus, and reproducing apparatus are respectively provided by each manufacturer apparatus.
- the root public key is used for signature verification of various public key certificates.
- the root private key is used by the key issuing authority to generate signatures for various public key certificates.
- the pair of the root public key and the root secret key is, for example, a RSA encryption public key and secret key pair. Since the RSA encryption is publicly known, the description thereof is omitted.
- the RSA encryption is an example, and other public key cryptosystems (digital signature schemes using public key cryptography) can be used.
- the controller ID storage unit 902 stores the controller ID.
- the controller ID is identification information of a controller incorporated in the recording medium device, and is generated by the controller manufacturer device and notified to the key issuing authority.
- identification information of a predetermined number of controllers for example, identification information for identifying controllers in the same lot
- the lot is a predetermined minimum production number unit at the time of production.
- the controller ID may be identification information of each controller (information for identifying each individual controller).
- the controller ID may be a concatenation value of controller manufacturer identification information for identifying the controller manufacturer and lot identification information for identifying the controller production lot.
- the bit length of the controller ID is, for example, 64 bits.
- the partial media ID generation unit 903 generates a partial media ID.
- the bit length of the partial media ID is, for example, 64 bits.
- y means that x and y are connected in this order.
- the bit length of the media ID is, for example, 128 bits.
- the recording medium device public key generation unit 904 and the recording medium device private key generation unit 906 each receive a recording medium device public key and a recording medium device private key corresponding to the recording medium device public key, which are different for each recording medium device. Generate.
- the pair of the recording medium device public key and the recording medium device private key is, for example, an RSA encryption public key and private key pair. Since the RSA encryption is publicly known, the description thereof is omitted.
- the media unique key generation unit 905 generates a media unique key.
- the media unique key is, for example, a 128-bit random value, and is generated differently for each recording medium device.
- a key called a media unique key does not have a specific meaning for the name, and may be called with a different name such as a controller individual key.
- the device identification information generation unit 907 includes a recording device ID that is information for uniquely specifying each recording device, a playback device ID that is information for uniquely specifying each playback device, and each key distribution server. Is generated as a key distribution server ID, which is information for uniquely identifying each.
- the recording device ID is device type information indicating whether it is a recording device or a playback device (for example, if the device type information is 1 bit and the device type information is “1”, the recording device is set to “0”.
- the recording device serial number for identifying the individual recording device may be notified from the recording device manufacturer.
- the playback device ID is device type information indicating whether the playback device is a recording device or a playback device (for example, if the device type information is 1 bit and the device type information is “1”, the recording device is set to “0”).
- a playback device manufacturer ID for uniquely identifying the playback device manufacturer, and a recording device serial number for identifying each playback device. May be included.
- the playback device serial number for identifying the individual playback device may be notified from the playback device manufacturer.
- the device type information is included in the recording device public key certificate or the playback device public key certificate, and the recording medium device uses the recording device public key certificate or the playback device public key certificate received from the counterpart device. Used to distinguish whether the counterpart device is a recording device or a playback device.
- the recording device / playback device / key distribution server public key generation unit 908 and the recording device / playback device / key distribution server private key generation unit 909 are: 1) a recording device public key that is different for each recording device; A recording device private key corresponding to the key, or 2) a reproduction device public key different for each individual reproduction device and a reproduction device private key corresponding to the reproduction device public key, or 3) each individual key distribution server A different key distribution server public key and a key distribution server private key corresponding to the key distribution server public key are generated.
- the key issuing authority secretly notifies the generated recording device secret key, reproducing device secret key, and key distribution server secret key to the recording device manufacturer device, the reproducing device manufacturer device, and the key distribution server, respectively.
- a pair of a recording device public key and a recording device private key, a pair of a playback device public key and a playback device private key, and a pair of a key distribution server public key and a key distribution server private key are, for example, an RSA encryption public key and private key It is a pair. Since the RSA encryption is publicly known, the description thereof is omitted.
- the recording medium device public key certificate generation unit 911 includes a controller ID stored by the controller ID storage unit 902, a partial media ID generated by the partial media ID generation unit 903, and a recording generated by the recording medium device public key generation unit 904.
- source information including at least the medium device public key
- signature information is generated using the root secret key
- the controller ID, the partial media ID, the recording medium device public key, and the generated signature are generated.
- a recording medium device public key certificate including at least information is generated.
- the generated recording medium apparatus public key certificate is notified from the key issuing authority to the recording medium apparatus manufacturer apparatus, and is stored in the recording medium apparatus by the recording medium apparatus manufacturer apparatus.
- the controller key storage unit 912 stores a controller key.
- the controller key is a key stored in the controller incorporated in the recording medium device, and is generated by the controller manufacturer device and notified to the key issuing authority.
- the controller key is unique for each predetermined number of controllers (for example, controllers in the same lot).
- the lot is a predetermined minimum production number unit at the time of production.
- the controller key is unique to each predetermined number of controllers, but is not limited to this configuration.
- the controller key may be unique for each controller (each individual controller).
- the encryption unit 913 uses a controller key in which the controller key storage unit 912 stores the media unique key generated by the media unique key generation unit 905 and the recording medium device secret key generated by the recording medium device secret key generation unit 906. To generate a temporary encrypted media unique key and a temporary encrypted recording medium device private key.
- the generated temporary encrypted media unique key and temporary encrypted recording medium device private key are notified from the key issuing authority to the recording medium device manufacturer device, and the recording medium device manufacturer device and the recording medium device are unique to the temporary encrypted media device.
- the key and the temporary encrypted recording medium device private key are once decrypted with the controller key, and the decrypted media unique key and the recording medium device private key are encrypted with the controller unique key described later, and the encrypted media unique key and the encrypted record are encrypted.
- a medium device secret key is generated and stored in the recording medium device.
- the recording device / reproducing device / key distribution server public key certificate generating unit 914 includes 1) device identification information indicating the recording device generated by the device identification information generating unit 907, and a recording device / reproducing device / key distribution server public key generating unit.
- the recording device public key certificate source information including at least the recording device public key generated by the unit 908, signature information is generated using the root private key, and the device identification information, the recording device public key, and the generated signature are generated.
- a recording device public key certificate including at least information is generated, or 2) device identification information indicating a reproduction device generated by the device identification information generation unit 907, and a recording device / reproduction device / key distribution server public key generation unit 908
- the playback device public key certificate source information including at least the playback device public key generated by the user
- signature information is generated using the root secret key, and the device identification information, the playback device public key
- generating a reproduction device public key certificate including at least the generated signature information or 3) key distribution including at least the key distribution server public key generated by the recording device / reproduction device / key distribution server public key generation unit 908
- For the server public key certificate source information signature information is generated using a root private key, and a key distribution server public key certificate including at least the key distribution server public key and the generated signature information is generated.
- the generated recording device public key certificate is notified from the key issuing authority to the recording device manufacturer device and stored in the recording device by the recording device manufacturer device.
- the generated reproducing device public key certificate is The key distribution authority notifies the reproduction apparatus manufacturer apparatus and stores it in the reproduction apparatus by the reproduction apparatus manufacturer apparatus.
- the generated key distribution server public key certificate is notified from the key distribution authority to the key distribution server and the key distribution server.
- the key distribution server 100 includes a content storage unit 101, a content division unit 102, a content distinction information generation unit 103, a key distribution server private key storage unit 104, Key distribution server public key certificate storage unit 105, common title key generation unit 106, common content storage unit 107, provisional title key generation unit 108, individualized content storage unit 109, encryption unit 110, encryption unit 111, route release
- the key storage unit 112, the authentication unit 113, the decryption unit 114, the encryption unit 115, and the encryption unit 116 are included.
- the content storage unit 101 is a database that stores various contents such as movies and music.
- the content dividing unit 102 divides the content into common content and individualized content according to a predetermined rule, stores the divided common content in the common content storage unit 106, and stores the individualized content in the individualized content storage unit 108.
- the common content is simply referred to as common content
- the individualized content is simply referred to as individualized content.
- the predetermined rule for example, when there are parts having different importance levels in the content, the part with high importance level may be the individualized content, and the part with low importance level may be the common content.
- a specific example of the part with high importance is, for example, a part that the copyright holder wants to reliably prevent copying.
- the content when there is no part with particularly different importance in the content, the content may be divided into two with a predetermined size, and one may be divided into common content and the other into individualized content. Note that the content dividing methods described here are merely examples, and the present invention is not limited to these methods.
- the content distinction information generation unit 103 is information for identifying whether it is common content or individualized content (this information is 1 bit, for example, “0” is common content, and “1” is individual content.
- Content distinction information including at least the content (meaning a digitized content).
- the common content divided by the content dividing unit 102 is assigned content distinction information including information indicating the common content, and the individualized content divided by the content dividing unit 102 is an individualized content.
- Content distinction information including information indicating is given.
- content division rule information indicating what kind of rule the content is divided into in the content distinction information, and individual content from which position to which position as common content from which position to which position of the original content It may include content division position information indicating whether or not.
- FIG. 18 shows an example of the data configuration when content distinction information is assigned to common content and individualized content, respectively.
- content distinction information is added to the head (header) of common content and individualized content
- the content distinction information is used when the common content and individualized content are encrypted. Is not encrypted (unencrypted). This is because the common content and the individualized content can be distinguished even when they are encrypted.
- the content distinction information is added to the head (header) of the common content and the individualized content, but the present invention is not limited to this configuration. That is, the content distinction information may be managed as separate data as long as it is associated with the common content and the individualized content.
- the key distribution server private key storage unit 104 stores the key distribution server private key notified from the key issuing authority 900.
- the key distribution server public key certificate storage unit 105 stores the key distribution server public key certificate notified from the key issuing authority 900.
- the common title key generation unit 106 generates a common title key used for encrypting the common content.
- the common title key is, for example, a 128-bit random value, and is different for each content.
- the common content storage unit 107 stores common content to which content distinction information is assigned.
- the content distinction information may be stored in a header portion of a file that stores the common content.
- the content distinction information is stored in a file different from the file that stores the common content, and the information that associates the file that stores the common content with the file that stores the content distinction information is the file that stores the common content, or , / And content distinction information may be included in the stored file.
- the provisional title key generation unit 108 stores a provisional title key used for encrypting the individualized content.
- the provisional title key is, for example, a 128-bit random value.
- the individualized content storage unit 109 stores the individualized content to which content distinction information is assigned.
- the method for assigning content distinction information to the individualized content is the same as the method for assigning content distinction information to the common content described above, and a description thereof will be omitted.
- the encryption unit 110 encrypts the common content stored in the common content storage unit 105 using the common title key stored in the common title key storage unit 103, and generates encrypted common content. Then, the generated encrypted common content is transmitted to the memory card.
- the content distinction information is not encrypted so that it can be identified even when the common content is encrypted.
- the encryption unit 111 encrypts the individualized content stored in the individualized content storage unit 106 with the provisional title key stored in the provisional title key generation unit 108, and generates the encrypted provisional individualization content. Then, the generated encrypted provisional personalized content is transmitted to the recording device.
- the content distinction information is not encrypted so that it can be identified even when the individualized content is encrypted.
- the root public key storage unit 112 stores the root public key notified from the key issuing authority 900.
- the authentication unit 113 stores a root public key stored in the root public key storage unit 112, a key distribution server private key stored in the key distribution server private key storage unit 104, and a key distribution server public key certificate storage unit 105.
- a mutual authentication process is performed with the authentication unit 302 of the memory card 300 using the key distribution server public key certificate, and a different session key is generated for each mutual authentication process. The detailed configuration and procedure of the mutual authentication process will be described later.
- the decryption unit 114 decrypts the encrypted and converted media unique key received from the memory card using the session key generated by the authentication unit 113, and generates the converted media unique key.
- the encryption unit 115 encrypts the common title key generated by the common title key generation unit 106 using the converted media unique key generated by the decryption unit 114 to generate an encrypted common title key. Then, the generated encrypted common title key is transmitted to the memory card.
- the encryption unit 116 encrypts the temporary title key generated by the temporary title key generation unit 108 using the converted media unique key generated by the decryption unit 114, and generates an encrypted temporary title key. Then, the generated encrypted provisional title key is transmitted to the memory card.
- AES Advanced Encryption Standard
- the recording device 200 includes a recording medium device private key storage unit 201, a recording device public key certificate storage unit 202, a decryption unit 203, and a root public key storage unit. 204, an authentication unit 205, a decryption unit 206, a decryption unit 207, and an encryption unit 208.
- the recording medium device private key storage unit 201 stores the recording medium device private key notified from the key issuing authority 900.
- the recording medium device certificate storage unit 202 stores the recording medium device public key certificate notified from the key issuing authority 900.
- the decryption unit 203 decrypts the encrypted provisional personalized content received from the key distribution server 100 using the provisional title key generated by the decryption unit 206, and generates personalized content.
- the root public key storage unit 204 stores the root public key notified from the key issuing authority 900.
- the authentication unit 205 includes a root public key stored in the root public key storage unit 204, a recording device private key stored in the recording device private key storage unit 201, and a recording device public key stored in the recording device public key certificate storage unit 202.
- mutual authentication processing is performed with the authentication unit 304 of the memory card 300, and a different session key is generated for each mutual authentication processing.
- the detailed configuration and procedure of the mutual authentication process will be described later.
- the decryption unit 206 decrypts the encrypted provisional title key received from the memory card 300 using the session key generated by the authentication unit 205, and generates a provisional title key.
- the decryption unit 207 decrypts the encrypted individualized title key received from the memory card 300 using the session key generated by the authentication unit 205, and generates an individualized title key.
- the encryption unit 208 encrypts the personalized content generated by the decryption unit 203 using the personalized title key generated by the decryption unit 207, and generates encrypted personalized content.
- the generated encrypted individualized content is transmitted to the memory card.
- AES Advanced Encryption Standard
- the memory card 300 includes a controller 330 and a memory unit 340.
- the controller performs processing such as reading / writing of data to / from the memory unit 340 of the memory card 300, and also performs mutual authentication processing and data in response to requests from the key distribution server 100, the recording device 200, and the playback device 400.
- the transmission / reception process etc. is performed.
- the controller 330 is composed of a semiconductor device such as an LSI
- the memory unit 340 is composed of, for example, a flash memory.
- the controller 330 further includes a root public key storage unit 301, an authentication unit 302, an encryption unit 303, an authentication unit 304, an encryption unit 305, an encryption unit 306, a controller ID storage unit 307, a media ID generation unit 308, a one-way From the sex conversion unit 309, the decryption unit 310, the controller unique number storage unit 311, the controller key storage unit 312, the individualized title key generation unit 313, the controller unique key generation unit 314, the decryption unit 315, the decryption unit 316, and the encryption unit 317 Composed.
- the memory unit 340 includes an encrypted recording medium device private key storage unit 318, a recording medium device public key certificate storage unit 319, an encrypted media unique key storage unit 320, an encrypted common title key storage unit 321, and an encrypted common content storage. 322, an encrypted individualized title key storage unit 323, and an encrypted individualized content storage unit 324.
- the root public key storage unit 301 stores the root public key notified from the key issuing authority 900.
- the authentication unit 302 includes a root public key stored in the root public key storage unit 301, a recording medium device private key generated by the decryption unit 315, and a recording medium device public key stored in the recording medium device public key certificate storage unit 319. Using the certificate, mutual authentication processing is performed with the authentication unit 113 of the key distribution server 100, and a different session key is generated for each mutual authentication processing. The detailed configuration and procedure of the mutual authentication process will be described later.
- the encryption unit 303 encrypts the converted media unique key generated by the unidirectional conversion unit 309 with the session key generated by the authentication unit 302, generates an encrypted converted media unique key, Alternatively, it is transmitted to the playback device.
- the authentication unit 304 includes a root public key stored in the root public key storage unit 301, a recording medium device private key generated by the decryption unit 315, and a recording medium device public key stored in the recording medium device public key certificate storage unit 319. Using the certificate, mutual authentication processing is performed with the authentication unit 205 of the recording device 200 and with the authentication unit 402 of the playback device 400, and a different session key is generated for each mutual authentication processing. The detailed configuration and procedure of the mutual authentication process will be described later.
- the encryption unit 305 encrypts the provisional title key generated by the decryption unit 310 with the session key generated by the authentication unit 304, and generates an encrypted provisional title key. Then, the encrypted temporary title key is transmitted to the recording device.
- the encryption unit 306 encrypts the individualized title key generated by the individualized title key generation unit 313 with the session key generated by the authentication unit 304 and generates an encrypted individualized title key. Then, the encrypted individualized title key is transmitted to the recording device.
- the controller ID storage unit 307 stores the controller ID.
- the media ID generation unit 308 generates a media ID from the controller ID stored in the controller ID storage unit 307 and the partial media ID included in the recording medium device public key certificate stored in the recording medium device public key certificate storage unit 319. To do.
- the one-way conversion unit 309 performs one-way conversion on the media unique key generated by the decryption unit 316 and generates a converted media unique key.
- the decryption unit 310 decrypts the encrypted temporary title key using the converted media unique key generated by the unidirectional conversion unit, and generates a temporary title key.
- the controller unique number storage unit 311 stores the controller unique number.
- the controller key storage unit 312 stores a controller key.
- the individualized title key generation unit 313 generates an individualized title key.
- the individualized title key is, for example, a 128-bit random value, and is different for each recording process.
- the controller unique key generation unit 314 generates a controller unique key from the controller key stored in the controller key storage unit 312 and the controller unique number stored in the controller unique number storage unit 311.
- the decryption unit 315 decrypts the encrypted recording medium device private key stored in the encrypted recording medium device private key storage unit 318 using the controller unique key generated by the controller unique key generation unit 314, and encrypts the encrypted recording medium device private key. Generate a key.
- the decryption unit 316 decrypts the encrypted media unique key stored in the encrypted media unique key storage unit 320 using the controller unique key generated by the controller unique key generation unit 314.
- the encryption unit 317 encrypts the individualized title key generated by the individualized title key generation unit 313 using the converted media unique key generated by the one-way conversion unit, and generates an encrypted individualized title key. . Then, it is stored in the encrypted individualized title key storage unit 323.
- the encrypted recording medium device private key storage unit 318 stores the encrypted recording medium device private key.
- This encrypted recording medium device private key is temporarily decrypted with the controller key by the recording medium device manufacturer device and the recording medium device using the controller key for the temporary encrypted recording medium device private key notified from the key issuing authority when the recording medium device is manufactured.
- the decrypted recording medium device secret key is generated by encrypting with the controller unique key.
- the recording medium device public key certificate storage unit 319 stores the recording medium device public key certificate notified from the key issuing authority 900.
- the encrypted media unique key storage unit 320 stores the encrypted media unique key.
- the encrypted media unique key is obtained by the recording medium device manufacturer device and the recording medium device once decrypting the temporary encrypted media unique key notified from the key issuing authority at the time of recording medium device manufacture with the controller key.
- the media unique key is generated by encrypting with the controller unique key.
- the encrypted common title key storage unit 321 stores the encrypted common title key received from the key distribution server 100.
- the encrypted common content storage unit 322 stores the encrypted common content received from the key distribution server 100.
- the encrypted individualized title key storage unit 323 stores the encrypted individualized title key generated by the encryption unit 317.
- the encrypted individualized content storage unit 324 stores the encrypted individualized content received from the recording device 200.
- AES Advanced Encryption Standard
- the playback device 400 includes a root public key storage unit 401, an authentication unit 402, a decryption unit 403, a decryption unit 404, a decryption unit 405, a decryption unit 406, and a decryption unit. 407, a playback device private key storage unit 408, and a playback device certificate storage unit 409.
- the root public key storage unit 401 stores the root public key notified from the key issuing authority 900.
- the authentication unit 402 includes a root public key stored in the root public key storage unit 401, a playback device private key stored in the playback device private key storage unit 408, and a playback device public key stored in the playback device public key certificate storage unit 409.
- mutual authentication processing is performed with the authentication unit 304 of the memory card 300, and a different session key is generated for each mutual authentication processing. The detailed configuration and procedure of the mutual authentication process will be described later.
- the decryption unit 403 decrypts the encrypted and converted media unique key received from the memory card 300 using the session key generated by the authentication unit 402, and generates a converted media unique key.
- the decryption unit 404 decrypts the encrypted common title key received from the memory card using the converted media unique key generated by the decryption unit 403, and generates a common title key.
- the decryption unit 405 decrypts the encrypted common content received from the memory card using the common title key generated by the decryption unit 404 and generates the common content.
- the decryption unit 406 uses the converted media unique key generated by the decryption unit 403 to decrypt the encrypted individualized title key received from the memory card, and generates an individualized title key.
- the decryption unit 407 decrypts the encrypted personalized content received from the memory card using the personalized title key generated by the decryption unit 406, and generates personalized content.
- the playback device private key storage unit 408 stores the playback device private key notified from the key issuing station 900.
- the playback device certificate storage unit 409 stores the playback device public key certificate notified from the key issuing authority 900.
- the content combining unit 410 combines the common content generated by the decryption unit 405 and the common content generated by the decryption unit 406 using the content distinction information to generate the original content.
- the playback unit 411 plays back the original content generated by the content combining unit 410.
- AES Advanced Encryption Standard
- FIG. 7 shows an example of detailed configurations of the authentication unit 113 of the key distribution server and the authentication unit 302 of the memory card.
- the authentication unit of the key distribution server further includes a random number generation unit 121, a signature verification unit 122, a signature verification unit 123, a signature generation unit 124, and a session key generation unit 125.
- the authentication unit of the memory card further includes a signature generation unit 331, a signature verification unit 332, a signature verification unit 333, a session key generation unit 334, and a random number generation unit 335.
- the random number generator 121 generates a random value.
- the random value is, for example, a 128-bit random value.
- the signature verification unit 122 verifies the signature included in the recording medium device public key certificate using the root public key and the recording medium device public key certificate received from the memory card, and if the signature verification is successful, The recording medium device public key included in the medium device public key certificate is considered valid.
- the signature verification unit 123 uses the recording medium device public key received from the signature verification unit 122 and the random number generated by the random number generation unit 121 to receive the random number received from the memory card. If the signature verification is successful, the partner memory card is authenticated as a valid memory card.
- the signature generation unit 124 generates a signature for the random number received from the memory card and transmits it to the memory card.
- the session key generation unit 125 generates a session key from the random number generated by the random number generation unit 121 and the random number received from the memory card when authenticating that the other party's memory card is a valid memory card.
- the session key generation for example, the following functions can be used.
- Session key AES_E (k, random number 1 (+) random number 2)
- AES_E (k, m) means that the input m is encrypted with the key k by AES encryption.
- a (+) B means an exclusive OR operation between A and B.
- k is a secret parameter secretly stored in advance in the session key generation unit
- random number 1 is a random number generated by the random number generation unit
- random number 2 is a random number received from the memory card.
- the signature generation unit 331 generates a signature for the random number received from the key distribution server and transmits it to the key distribution server.
- the signature verification unit 332 verifies the signature included in the key distribution server public key certificate using the root public key and the key distribution server public key certificate received from the key distribution server, and if the signature verification is successful, The key distribution server public key included in the key distribution server public key certificate is considered valid.
- the signature verification unit 333 receives the key distribution server public key received from the signature verification unit 332 and the random number generated by the random number generation unit 334 from the key distribution server.
- the signature for the random number is verified, and if the signature verification is successful, the partner key distribution server is authenticated as a valid key distribution server.
- the session key generation unit 334 generates a session key from the random number generated by the random number generation unit 335 and the random number received from the key distribution server when authenticating that the partner key distribution server is a valid key distribution server.
- the session key generation for example, the following functions can be used.
- Session key AES (k, random number 1 (+) random number 2)
- k is a secret parameter secretly stored in advance in the session key generation unit
- random number 1 is a random number received from the key distribution server
- random number 2 is a random number generated by the random number generation unit 335.
- the random number generation unit 335 generates a random value.
- the random value is, for example, a 128-bit random value.
- the RSA encryption method can be used as the signature generation / signature verification algorithm used in the signature generation unit 123 and the signature verification units 122 and 123.
- the RSA encryption method is an example, and other public key encryption methods (digital signature methods using public key encryption technology) can be used.
- the configuration shown here is merely an example, and other configurations may be used.
- Detailed configurations of the authentication unit 205 of the recording device and the authentication unit 402 of the playback device are the same as the detailed configuration of the authentication unit 113 of the key distribution server, and thus description thereof is omitted.
- the controller unique key generation unit 314 of the memory card 300 generates a controller unique key from the controller unique number stored in the controller unique number storage unit 311 and the controller key stored in the controller key storage 312 (S101).
- the controller unique key is generated by the following function, for example.
- Controller unique key AES_E (controller ID, controller key) (+) controller key
- AES_E (k, m) means AES encryption, which means that the input m is encrypted with the key k.
- a (+) B means an exclusive OR operation between A and B.
- the decryption unit 315 decrypts the encrypted recording medium device private key stored in the encrypted recording medium device private key storage unit 318 with the controller unique key generated in step S101 to generate a recording medium device private key. (S102).
- the authentication unit 302 of the memory card 300 performs a mutual authentication process with the authentication unit 113 of the key distribution server 100 (S103).
- the decryption unit 316 when the memory card 300 succeeds in the mutual authentication process in step S103, the decryption unit 316 generates the encrypted media unique key stored in the encrypted media unique key storage unit 320 in the controller unique key generated in step S101. To generate a media unique key (S104).
- the media ID generation unit 308 concatenates the controller ID stored in the controller ID storage unit 307 and the partial media ID included in the recording medium device public key certificate stored in the recording medium device public key certificate storage unit 319.
- the media ID is generated (S105).
- FIG. 16 shows an example of the data structure of the media ID.
- the unidirectional conversion unit 309 performs unidirectional conversion using the media ID generated in step S105 and the media unique key generated in step S104 as input, and generates a converted media unique key (S106).
- the following functions can be used as an example of the unidirectional conversion.
- Post-conversion media unique key AES_E (media ID, media unique key) (+) media unique key
- AES_E (k, m) indicates that the input m is encrypted with the key k using AES encryption.
- X (+) y is an exclusive OR operation of x and y.
- the encryption unit 303 encrypts the converted media unique key generated in step S106 with the session key generated as a result of the mutual authentication processing in step S103, generates an encrypted converted media unique key, It transmits to a delivery server (S107).
- the key distribution server 100 Upon receiving the encrypted and converted media unique key from the memory card in step S107, the key distribution server 100 generates the received encrypted and converted media unique key as a result of the mutual authentication process in step S103. Decrypted with the session key, and generates a converted media unique key (S108).
- the common title key generation unit 106 generates a common title key (S109).
- the common title key is, for example, a 128-bit random value.
- the encryption unit 115 encrypts the common title key generated in step S109 using the converted media unique key generated in step S108, generates an encrypted common title key, and transmits it to the memory card ( S110).
- the memory card 300 stores the encrypted common title key received in step S110 in the encrypted common title key storage unit 321 (S111).
- the content dividing unit 102 of the key distribution server 100 acquires content to be distributed from the content stored in the content storage unit 101, and divides the acquired content into common content and individualized content ( S112).
- the content distinction information generation unit 103 generates content distinction information, assigns it to the common content and the individualized content, stores the common content in the common content storage unit 107, and stores the individualized content in the individualized content storage unit 109. (S113).
- step 112 and step S113 are not necessarily processed at this timing, and the key distribution server may perform the process of step 112 and step S113 on all contents in advance.
- the encryption unit 110 encrypts the common content generated in step S112 using the common title key generated in step S109, generates the encrypted common content, and transmits it to the memory card (S114). .
- the memory card 300 stores the encrypted common content received in step S114 in the encrypted common content storage unit 322 (S115).
- the provisional title key generation unit 108 of the key distribution server 100 generates a provisional title key (S116).
- the provisional title key is, for example, a 128-bit random value.
- the encryption unit 116 encrypts the temporary title key generated in step S116 using the converted media unique key generated in step S108, generates an encrypted temporary title key, and transmits it to the memory card. (S117).
- the decryption unit 310 decrypts the encrypted provisional title key with the converted media unique key generated in step S106, and obtains the provisional title key. Generate (S118).
- the encryption unit 111 of the key distribution server 100 encrypts the personalized content generated in step S112 with the temporary title key generated in step 116, generates encrypted temporary personalized content, and stores it in the recording device. Transmit (S119).
- the authentication unit 304 of the memory card 300 performs mutual authentication processing with the authentication unit 205 of the recording device 200, and the authentication unit 304 of the memory card 300 is a recording device or a playback device. (S120).
- step S120 The authentication process in step S120 is triggered by the fact that the memory card 300 has decrypted the encrypted provisional title key in step S118, or the recording apparatus 200 sends an encrypted provisional individual from the key distribution server 100 in step S119. Triggered by the reception of the digitized content.
- step S120 If the mutual authentication process in step S120 is successful and the authentication partner is a recording device, the temporary title key generated in step 118 by the encryption unit 305 of the memory card using the session key generated by the mutual authentication process in step S120. And the encrypted provisional title key is transmitted to the recording device (S121).
- the decryption unit 206 of the recording device 200 decrypts the encrypted provisional title key received in step S121 with the session key generated by the mutual authentication process in step S120, and generates a provisional title key (S122).
- the individualized title key generation unit 313 of the memory card generates an individualized title key (S123).
- the individualized title key is, for example, a 128-bit random value.
- the encryption unit 317 encrypts the individualized title key generated in step S123 with the converted media unique key generated in step S106, generates an encrypted individualized title key, and encrypts the individualized key. It is stored in the title key storage unit (S124).
- the encryption unit 306 encrypts the individualized title key generated in step S123 with the session key generated by the mutual authentication process in step S120, generates an encrypted individual title key, and stores it in the recording device 200. Transmit (S125).
- the decryption unit 207 decrypts the encrypted individualized title key received in step S125 with the session key generated by the mutual authentication process in step S120, and generates an individualized title key (S126).
- the decryption unit 203 decrypts the encrypted provisional personalized content received in step S119 with the provisional title key generated in step S122, and generates personalized content (S127).
- the encryption unit 208 encrypts the individualized content generated in step S127 with the individualized title key generated in step S126, generates encrypted individualized content, and transmits it to the memory card. (S128).
- the memory card stores the encrypted individualized content received in step 128 in the encrypted individualized content storage unit 324 (S129).
- FIG. 11 shows a detailed operation flow of authentication processing between the key distribution server and the memory card.
- the memory card 300 transmits the recording medium device public key certificate to the key distribution server 100 (S201).
- the key distribution server uses the recording medium device public key certificate received in step S201 by the signature verification unit 122 of the key distribution server and the received record using the root public key stored in the root public key storage unit.
- the signature included in the medium device public key certificate is verified (S202). If verification fails, the authentication process is terminated. If the verification is successful, the recording medium device public key included in the recording medium device public key certificate is regarded as valid.
- the key distribution server transmits the key distribution server public key certificate to the memory card (S203).
- the signature verification unit 332 of the memory card receives the key distribution server public key certificate received using the key distribution server public key certificate received in step S203 and the root public key stored in the root public key storage unit.
- the signature included in is verified (S204). If verification fails, the authentication process is terminated. If the verification is successful, the key distribution server public key included in the key distribution server public key certificate is regarded as valid.
- the random number generation unit 121 when the verification is successful in step S202, the random number generation unit 121 generates a random number and transmits it to the memory card (S205).
- the random number is, for example, a 128-bit random value.
- the signature generation unit 331 of the memory card generates a signature for the random number received from the key distribution server by using the recording medium device private key, and transmits the signature to the key distribution server (S206).
- the key distribution server verifies the signature received in S204 using the random number generated in step 205 and the recording medium device public key deemed valid in step 202 (S207). If verification fails, the authentication process is terminated. If the verification is successful, the partner's memory card is authenticated as a valid memory card.
- the random number generation unit 335 When the memory card 300 is successfully verified in step S204, the random number generation unit 335 generates a random number and transmits it to the key distribution server (S208).
- the random number is, for example, a 128-bit random value.
- the signature generation unit 124 of the key distribution server generates a signature for the random number received from the recording medium device by using the key distribution server private key and transmits it to the memory card (S209).
- the memory card verifies the signature received in S209 using the random number generated in Step 208 and the key distribution server public key deemed valid in Step 204 (S210). If verification fails, the authentication process is terminated. If the verification is successful, the partner key distribution server is authenticated as a valid key distribution server.
- the session key generation unit 125 of the key distribution server 100 generates a session key from the random number generated in step S205 and the random number received in step S208 (S211).
- the session key generation unit 334 of the memory card 300 generates a session key from the random number generated in step S208 and the random number received in step S205 (S212).
- FIG. 12 shows a detailed operation flow of authentication processing between the recording device and the memory card.
- the memory card 300 transmits the recording medium device public key certificate to the recording device 200 (S301).
- the recording apparatus 200 receives the recording medium apparatus received by the signature verification unit of the recording apparatus using the recording medium apparatus public key certificate received in step S301 and the root public key stored in the root public key storage part.
- the signature included in the public key certificate is verified (S302). If verification fails, the authentication process is terminated. If the verification is successful, the recording medium device public key included in the recording medium device public key certificate is regarded as valid.
- the recording device transmits the recording device public key certificate to the memory card (S303).
- the signature verification unit 332 of the memory card is included in the received recording device public key certificate using the recording device public key certificate received in step S303 and the root public key stored in the root public key storage unit.
- the signature to be verified is verified (S304). If verification fails, the authentication process is terminated. If the verification is successful, the recording device public key included in the recording device public key certificate is regarded as valid. Further, from the apparatus type information included in the recording apparatus ID included in the recording apparatus public key certificate, it is confirmed whether the other party is a recording apparatus or a reproducing apparatus, and the apparatus type information indicates that the other party is a reproducing apparatus. The process ends. Subsequent steps S305 to S312 are the same as steps S205 to S212 in the detailed operation flow of the mutual authentication process between the memory card and the key distribution server, and thus description thereof is omitted.
- FIG. 17A shows an example of the data structure of the recording medium device public key certificate.
- the recording medium device public key certificate includes a controller ID, a partial media ID, a recording medium device public key, and a signature.
- the signature is generated by, for example, the following expression for the concatenation of the controller ID, the partial media ID, and the recording medium device public key using the root secret key.
- Signature RSA_SIGN (root secret key, controller ID
- s RSA_SIGN (k, m) means that the signature s for the input m is generated with the secret key k using the RSA signature generation function. Since the RSA signature generation function is publicly known, description thereof is omitted.
- FIG. 17 (b) shows an example of the data structure of the key distribution server public key certificate.
- the key distribution server public key certificate is composed of a key distribution server ID, which is information for uniquely identifying the key distribution server, a key distribution server public key, and a signature.
- the signature is generated by, for example, the following expression for the concatenation of the key distribution server ID and the key distribution server public key using the root secret key.
- FIG. 17C shows an example of the data structure of the recording device public key certificate.
- the recording device public key certificate includes a recording device ID that is information for uniquely identifying the recording device, a recording device public key, and a signature.
- the recording device ID further includes device type information indicating whether the recording device is a reproducing device, a recording device manufacturer ID for uniquely identifying the recording device manufacturer, and an individual of each recording device. Recording device serial number.
- the signature is generated, for example, by the following formula for the concatenation of the recording device ID and the recording device public key using the root secret key.
- the recording device ID is, for example, a 32-bit numerical value.
- FIGS. 13 to 14 show an example of the detailed operation flow when content recorded on the memory card 300 is played back by the playback device.
- step S401 to step S408, content distribution This is exactly the same as steps S101 to S108 in the memory card and key distribution server at the time of recording.
- the controller unique key generation unit 314 of the memory card 300 generates a controller unique key from the controller unique number stored in the controller unique number storage unit 311 and the controller key stored in the controller key storage 312 (S401). .
- the controller unique key is generated by the following function, for example.
- Controller unique key AES_E (controller unique number, controller key) (+) controller key
- AES_E (k, m) means AES encryption, which means that the input m is encrypted with the key k.
- a (+) B means an exclusive OR operation between A and B.
- the decryption unit 315 decrypts the encrypted recording medium device private key stored in the encrypted recording medium device private key storage unit 318 with the controller unique key generated in step S401, and generates a recording medium device private key. (S402).
- the authentication unit 302 of the memory card 300 performs mutual authentication processing with the authentication unit 402 of the playback device 400 (S403).
- the decryption unit 316 when the memory card 300 succeeds in the mutual authentication process in step S403, the decryption unit 316 generates the encrypted media unique key stored in the encrypted media unique key storage unit 320 in the controller unique key generated in step S401. To generate a media unique key (S404).
- the media ID generation unit 308 concatenates the controller ID stored in the controller ID storage unit 307 and the partial media ID included in the recording medium device public key certificate stored in the recording medium device public key certificate storage unit 319. Then, a media ID is generated (S405).
- the unidirectional conversion unit 309 performs unidirectional conversion using the media ID generated in step S405 and the media unique key generated in step S404 as input, and generates a converted media unique key (S406).
- the following functions can be used as an example of the unidirectional conversion.
- Post-conversion media unique key AES_E (media ID, media unique key) (+) media unique key
- AES_E (k, m) indicates that the input m is encrypted with the key k using AES encryption. . (+) Is an exclusive OR operation.
- the encryption unit 303 encrypts the converted media unique key generated in step S406 with the session key generated as a result of the mutual authentication process in step S403, generates an encrypted converted media unique key, and plays it.
- the data is transmitted to the device (S407).
- the decryption unit 403 When the playback apparatus 400 receives the encrypted and converted media unique key from the memory card in step S407, the decryption unit 403 generates the received encrypted and converted media unique key as a result of the mutual authentication process in step S403. It decrypts with the key and generates a converted media unique key (S408).
- the memory card 300 transmits the encrypted common title key stored in the encrypted common title key storage unit 321 to the playback device (S409).
- the decryption unit 404 of the playback device 400 decrypts the received encrypted common title key with the converted media unique key generated in step S408, and generates a common title key (S410).
- the memory card 300 transmits the encrypted common content stored in the encrypted common content storage unit 322 to the playback device (S411).
- the decryption unit 405 of the playback device 400 decrypts the received encrypted common content with the common title key generated in step S410, and generates the common content (S412).
- the memory card 300 transmits the encrypted individualized title key stored in the encrypted individualized title key storage unit 323 to the playback device (S413).
- the decryption unit 406 of the playback device 400 decrypts the received encrypted individualized title key with the converted media unique key generated in step S408, and generates an individualized title key (S414).
- the memory card 300 transmits the encrypted individualized content stored in the encrypted individualized content storage unit 324 to the playback device (S415).
- the decryption unit 407 of the playback device 400 decrypts the received encrypted personalized content with the personalized title key generated in step S414, and generates personalized content (S416).
- the content combining unit 410 of the playback device 200 combines the common content generated in step S412 and the individualized content generated in step S416 based on the content distinction information assigned to each to generate content. (S417).
- the playback unit 411 of the playback device plays back the content generated in S417 (S418).
- FIG. 15 shows a detailed operation flow of authentication processing between the playback device 400 and the memory card 300.
- the memory card 300 transmits the recording medium device public key certificate to the playback device 400 (S501).
- the playback apparatus 400 uses the recording medium device public key certificate received by the signature verification unit of the playback device in step S501 and the root public key stored in the root public key storage unit to receive the recording medium device.
- the signature included in the public key certificate is verified (S502). If verification fails, the authentication process is terminated. If the verification is successful, the recording medium device public key included in the recording medium device public key certificate is regarded as valid.
- the playback device transmits the playback device public key certificate to the memory card (S503).
- the signature verification unit 332 of the memory card uses the playback device public key certificate received in step S503 and the root public key stored in the root public key storage unit, and is included in the received playback device public key certificate.
- the signature to be verified is verified (S504). If verification fails, the authentication process is terminated. If the verification is successful, the playback device public key included in the playback device public key certificate is regarded as valid. Further, from the device type information included in the playback device ID included in the playback device public key certificate, it is confirmed whether the partner is a recording device or a playback device, and the device type information indicates that the partner is a recording device, The process ends. Subsequent steps S505 to S512 are the same as steps S205 to S212 in the detailed operation flow of the mutual authentication process between the memory card and the key distribution server, and thus description thereof will be omitted.
- FIG. 17D shows an example of the data configuration of the playback device public key certificate.
- the playback device public key certificate includes a playback device ID that is information for uniquely identifying the playback device, a playback device public key, and a signature.
- the playback device ID further includes device type information indicating whether it is a recording device or a playback device, a playback device manufacturer ID for uniquely identifying the playback device manufacturer, and an individual of each playback device.
- the playback device serial number is a playback device ID that is information for uniquely identifying the playback device, a playback device public key, and a signature.
- the playback device ID further includes device type information indicating whether it is a recording device or a playback device, a playback device manufacturer ID for uniquely identifying the playback device manufacturer, and an individual of each playback device.
- the signature is generated by, for example, the following expression for the concatenation of the playback device ID and the playback device public key using the root secret key.
- the playback device ID is, for example, a 32-bit numerical value.
- the individualized title key generation unit 313 of the memory card 300 generates, for example, a 128-bit random value as the individualized title key.
- the configuration is not limited to this.
- the memory card is a record verified by the individualized title key generation unit 313 of the memory card 300 in the verification step of the recording device public key certificate in step 304 of FIG. 12 in the individual key generation step of step S123 of FIG.
- the individualized title A key may be generated.
- AES_E (S, recording device ID
- AES_E (k, m) means that the input m is encrypted with the key k using AES encryption.
- random number value means that the recording device ID and the random value are connected in this order.
- the recording device ID is, for example, a 32-bit numerical value
- the random value is, for example, 96 bits.
- a content decryption tool that decrypts a key obtains a common title key and an individualized title key and publishes them on a Web server, and obtains the public common title key and individualized title key and decrypts the encrypted content
- the key issuing authority obtains the content decryption tool, identifies the individualized title key published on the Web server, and identifies the recording device ID from the identified individualized title key by the following formula be able to.
- Recording device ID [AES_D (S, individualized title key)] upper 32 bits
- AES_D (k, c) means that the ciphertext c is decrypted with the key k using the AES decryption function.
- [X] upper 32 bits means that the upper 32 bits of x are extracted.
- the key issuing authority can specify the recording device ID from the individualized title key disclosed on the Web server, the key issuing authority can invalidate the recording device public key certificate including the specified recording device ID. Is possible. A specific method of invalidation will be described later.
- the overall configuration of the recording / reproducing system according to Embodiment 2 of the present invention is the same as that of Embodiment 1, and the recording / reproducing system includes a key distribution server 100A, a recording device 200A, and a recording medium device 300A. And a playback device 400A and a key issuing station 900A.
- the recording medium device 300A is a memory card
- the key distribution server 100A includes a content storage unit 101A, a content division unit 102A, a content distinction information generation unit 103A, a key distribution server private key storage unit 104A, Key distribution server public key certificate storage unit 105A, common title key generation unit 106A, common content storage unit 107A, individualized title key generation unit 151A, individualized content storage unit 109A, encryption unit 110A, root public key storage unit 112A
- the key distribution server 100A the content storage unit 101A, content division unit 102A, content distinction information generation unit 103A, key distribution server private key storage unit 104A, key distribution server public key certificate storage unit 105A, common title key generation
- the key distribution of the first embodiment is performed for the unit 106A, the common content storage unit 107A, the individualized content storage unit 109A, the encryption unit 110A, the root public key storage unit 112A, the authentication unit 113A, the decryption unit 114A, and the encryption unit 115A.
- Content storage unit 101 Content storage unit 101, content division unit 102, content distinction information generation unit 103, key distribution server private key storage unit 104, key distribution server public key certificate storage unit 105, common title key generation unit 106, common content in server 100 Storage unit 107, individualized content storage 109, the encryption unit 110, the root public key storage unit 112, authentication unit 113, decoding unit 114, an encryption unit 115, since each is the same, the description thereof is omitted.
- the individualized title key generation unit 151A generates an individualized title key.
- the individualized title key is, for example, a 128-bit random number value and is different for each distribution process.
- the individualized title key is, for example, a 128-bit random value, but is not limited to this configuration. See modification (1).
- the encryption unit 152A encrypts the individualized title key generated by the individualized title key generation unit 151A using the converted media unique key generated by the decryption unit 114A, generates an encrypted individualized title key, and Send to card.
- the authentication unit 153A stores the root public key stored in the root public key storage unit 112A, the key distribution server private key stored in the key distribution server private key storage unit 104A, and the key distribution server public key certificate storage unit 105A. Using the key distribution server public key certificate, a mutual authentication process is performed with the authentication unit 251A of the recording apparatus 200A, and a different session key is generated for each mutual authentication process. The detailed configuration and procedure of the mutual authentication process will be described later.
- the encryption unit 154A encrypts the individualized title key generated by the individualized title key generation unit 151A using the session key generated by the authentication unit 153A, generates an encrypted individualized title key, and stores it in the recording device 200A. Send.
- the encryption unit 155A encrypts the personalized content stored in the personalized content storage unit 109A using the session key generated by the authentication unit 153A, generates encrypted personalized content, and transmits the encrypted personalized content to the recording apparatus 200A. .
- the recording device 200A includes a recording medium device private key storage unit 201A, a recording device public key certificate storage unit 202A, a root public key storage unit 204A, and an authentication unit. 251A, a decryption unit 252A, a decryption unit 253A, and an encryption unit 254A.
- the recording device private key storage unit 201A, the recording device public key certificate storage unit 202A, and the root public key storage unit 204A in the recording device 200A are stored in the recording device private key storage in the recording device 200 of the first embodiment. Since this is the same as the unit 201, the recording device public key certificate storage unit 202, and the root public key storage unit 204, description thereof will be omitted.
- the authentication unit 251A includes a root public key stored in the root public key storage unit 204A, a recording device private key stored in the recording device private key storage unit 201A, and a recording device public key stored in the recording device public key certificate storage unit 202A.
- a mutual authentication process is performed with the authentication unit 153A of the key distribution server 100 using the key certificate, and a different session key is generated for each mutual authentication process. The detailed configuration and procedure of the mutual authentication process will be described later.
- the decryption unit 252A decrypts the encrypted individualized title key received from the key distribution server with the session key generated by the authentication unit 251A, and generates an individualized title key.
- the decryption unit 253A decrypts the encrypted individualized content received from the key distribution server with the session key generated by the authentication unit 251A, and generates the individualized content.
- the encryption unit 254A encrypts the personalized content generated by the decryption unit 253A using the personalized title key generated by the decryption unit 252A, generates encrypted personalized content, and transmits it to the memory card.
- the memory card 300A includes a controller 330A and a memory unit 340A.
- the controller performs processing such as reading / writing of data to / from the memory unit 340A of the memory card 300A, and performs mutual authentication processing and data in response to requests from the key distribution server 100A, the recording device 200A, and the playback device 400A.
- the transmission / reception process etc. is performed.
- the controller 330A includes a semiconductor device such as an LSI
- the memory unit 340A includes, for example, a flash memory.
- the controller 330A further includes a root public key storage unit 301A, an authentication unit 302A, an encryption unit 303A, a controller ID storage unit 307A, a media ID generation unit 308A, a one-way conversion unit 309A, a controller unique number storage unit 311A, and a controller key.
- the storage unit 312A includes a controller unique key generation unit 314A, a decryption unit 315A, and a decryption unit 316A.
- the memory unit 340A includes an encrypted recording medium device private key storage unit 318A, a recording medium device public key certificate storage unit 319A, an encrypted media unique key storage unit 320A, an encrypted common title key storage unit 321A, and an encrypted common content storage. 322A, an encrypted individualized title key storage unit 323A, and an encrypted individualized content storage unit 324A.
- the key storage unit 312A, the controller unique key generation unit 314A, the decryption unit 315A, and the decryption unit 316A are the root public key storage unit 301, the authentication unit 302, the encryption unit 303, the controller ID storage unit 307 in the controller of the first embodiment, Since the media ID generation unit 308, the unidirectional conversion unit 309, the controller unique number storage unit 311, the controller key storage unit 312, the controller unique key generation unit 314, the decryption unit 315, and the decryption unit 316 are exactly the same, respectively, Omitted.
- the encrypted recording medium device private key storage unit 318A, the recording medium device public key certificate storage unit 319A, the encrypted media unique key storage unit 320A, the encrypted common title key storage unit 321A, the encrypted common The content storage unit 322A, the encrypted individualized title key storage unit 323A, and the encrypted individualized content storage unit 324A are respectively an encrypted recording medium device private key storage unit 318 and a recording medium device in the memory unit 340 of the first embodiment.
- the description of the part 324 is omitted because it is exactly the same as the part 324.
- FIG. 22 shows an example of the detailed configuration of the authentication unit 153A of the key distribution server and the authentication unit 251A of the recording device.
- the authentication unit of the key distribution server further includes a random number generation unit 121A, a signature verification unit 122A, a signature verification unit 123A, a signature generation unit 124A, and a session key generation unit 125A.
- the authentication unit of the recording apparatus further includes a signature generation unit 221A, a signature verification unit 222A, a signature verification unit 223A, a session key generation unit 224A, and a random number generation unit 225A.
- the random number generation unit 121A, signature verification unit 122A, signature verification unit 123A, signature generation unit 124A, and session key generation unit 125A in the authentication unit of the key distribution server are the same as the random number generation unit 121 and signature verification in the first embodiment. Since this is the same as the section 122, the signature verification section 123, the signature generation section 124, and the session key generation section 125, a description thereof will be omitted. Further, the authentication unit of the recording apparatus has the same configuration as the detailed configuration of the authentication unit 113A of the key distribution server, and thus description thereof is omitted.
- steps S101A to S115A shown below are exactly the same as steps S101 to S115 in the first embodiment.
- the controller unique key generation unit 314A of the memory card 300A generates a controller unique key from the controller unique number stored in the controller unique number storage unit 311A and the controller key stored in the controller key storage 312A (S101A).
- the controller unique key is generated by the following function, for example.
- Controller unique key AES_E (controller ID, controller key) (+) controller key
- AES_E (k, m) means AES encryption, which means that the input m is encrypted with the key k.
- a (+) B means an exclusive OR operation between A and B.
- the decryption unit 315A decrypts the encrypted recording medium device private key stored in the encrypted recording medium device private key storage unit 318A with the controller unique key generated in step S101A, and generates a recording medium device private key. (S102A).
- the authentication unit 302A of the memory card 300A performs a mutual authentication process with the authentication unit 113A of the key distribution server 100A (S103A).
- the decryption unit 316A when the memory card 300A succeeds in the mutual authentication process in step S103A, the decryption unit 316A generates the encrypted media unique key stored in the encrypted media unique key storage unit 320A in the controller unique key generated in step S101A. To generate a media unique key (S104A).
- the media ID generation unit 308A concatenates the controller ID stored in the controller ID storage unit 307A and the partial media ID included in the recording medium device public key certificate stored in the recording medium device public key certificate storage unit 319A.
- the media ID is generated (S105A).
- An example of the data structure of the media ID is the same as the media ID of the first embodiment shown in FIG.
- the unidirectional conversion unit 309A performs unidirectional conversion using the media ID generated in step S105A and the media unique key generated in step S104A as input, and generates a converted media unique key (S106A).
- the following functions can be used as an example of the unidirectional conversion.
- Post-conversion media unique key AES_E (media ID, media unique key) (+) media unique key
- AES_E (k, m) indicates that the input m is encrypted with the key k using AES encryption.
- X (+) y is an exclusive OR operation of x and y.
- the encryption unit 303A encrypts the converted media unique key generated in step S106A with the session key generated as a result of the mutual authentication processing in step S103A, generates an encrypted converted media unique key, It is transmitted to the distribution server (S107A).
- the key distribution server 100A Upon receiving the encrypted and converted media unique key from the memory card in step S107A, the key distribution server 100A generates the received encrypted and converted media unique key as a result of the mutual authentication process in step S103A. Decrypt with the session key and generate a converted media unique key (S108A).
- the common title key generation unit 106A generates a common title key (S109A).
- the common title key is, for example, a 128-bit random value and is unique for each content.
- the encryption unit 115A encrypts the common title key generated in step S109A using the converted media unique key generated in step S108A, generates an encrypted common title key, and transmits it to the memory card ( S110A).
- the memory card 300A stores the encrypted common title key received in step S110A in the encrypted common title key storage unit 321A (S111A).
- the content dividing unit 102A of the key distribution server 100A acquires content to be distributed from the content stored in the content storage unit 101A, and divides the acquired content into common content and individualized content ( S112A).
- the content distinction information generation unit 103A generates content distinction information, assigns it to the common content and the individualized content, and stores the common content in the common content storage unit 107A and the individualized content in the individualized content storage unit 109A. (S113A).
- step 112A and step S113A do not necessarily have to be processed at this timing, and the key distribution server may perform the processing of step 112A and step S113A on all contents in advance.
- the encryption unit 110A encrypts the common content generated in step S112A using the common title key generated in step S109A, generates the encrypted common content, and transmits it to the memory card (S114A). .
- the memory card 300A stores the encrypted common content received in step S114A in the encrypted common content storage unit 322A (S115A).
- the individual title key generation unit 151A of the key distribution server 100A generates an individualized title key (S116A).
- the individualized title key is, for example, a 128-bit random value.
- the encryption unit 152A encrypts the individualized title key generated in step S116A with the converted media unique key generated in step S108A, generates an encrypted individual title key, and transmits it to the memory card 300A ( S117A).
- the memory card stores the encrypted individual title key received in step S117A in the encrypted individual title key storage unit 323A (S118A).
- the authentication unit 153A of the key distribution server 100A performs a mutual authentication process with the authentication unit 251A of the recording device 200A (S119A).
- the encryption unit 154A of the key distribution server 100A encrypts the individualized title key generated in step S116A using the session key generated as a result of the authentication process in step S119A, and encrypts the individualized title.
- a key is generated and transmitted to the recording apparatus 200A (S120A).
- the decryption unit 252A of the recording device 200A decrypts the encrypted individualized title key received in step S120A using the session key generated as a result of the authentication process in step S119A, and the individualized title key is obtained.
- the encryption unit 155A of the key distribution server 100A encrypts the individualized content generated in step S112A using the session key generated as a result of the authentication process in step S119A, and encrypts the individualized content. Is transmitted to the recording apparatus 200A (S122A).
- the decryption unit 253A of the recording device 200A decrypts the encrypted individualized content received in step S122A using the session key generated as a result of the authentication process in step S119A, thereby generating individualized content ( S123A).
- the encryption unit 254A encrypts the personalized content generated in step S123A with the personalized title key generated in step 121A, generates encrypted personalized content, and transmits it to the memory card (S124A).
- the memory card 300A stores the encrypted individualized content received in step S124A in the encrypted individualized content storage unit 324A (S125A).
- FIG. 25 shows a detailed operation flow of authentication processing between the key distribution server and the recording device.
- the recording apparatus 200A transmits the recording apparatus public key certificate to the key distribution server 100A (S601A).
- the signature verification unit 122A of the key distribution server 100A uses the recording device public key certificate received in step S601A and the root public key stored in the root public key storage unit to receive the recording device public key certificate. (S602A). If verification fails, the authentication process is terminated. If the verification is successful, the recording device public key included in the recording device public key certificate is regarded as valid.
- the key distribution server 100A transmits the key distribution server public key certificate to the recording device 200A (S603A).
- the signature verification unit 222A of the recording apparatus 200A receives the received key distribution server public key certificate using the key distribution server public key certificate received in step S602A and the root public key stored in the root public key storage unit.
- the signature included in the document is verified (S604A). If verification fails, the authentication process is terminated. If the verification is successful, the key distribution server public key included in the key distribution server public key certificate is regarded as valid.
- the random number generation unit 121A when the verification is successful in step S602A, the random number generation unit 121A generates a random number and transmits it to the recording device (S605A).
- the random number is, for example, a 128-bit random value.
- the signature generation unit 221A of the recording device generates a signature for the random number received from the key distribution server using the recording device private key, and transmits the signature to the key distribution server (S606A).
- the key distribution server verifies the signature received in S604A using the random number generated in step 605A and the recording device public key deemed valid in step 602A (S607A). If verification fails, the authentication process is terminated. If the verification is successful, the other recording device is authenticated as a valid recording device.
- the random number generation unit 225A generates a random number and transmits it to the key distribution server (S608A).
- the random number is, for example, a 128-bit random value.
- the signature generation unit 124A of the key distribution server generates a signature for the random number received from the recording device using the key distribution server private key, and transmits the signature to the recording device (S609A).
- the recording apparatus verifies the signature received in S609A using the random number generated in Step 608A and the key distribution server public key deemed valid in Step 604A (S610A). If verification fails, the authentication process is terminated. If the verification is successful, the partner key distribution server is authenticated as a valid key distribution server.
- the session key generation unit 125A of the key distribution server 100A generates a session key from the random number generated in step S605A and the random number received in step S608A (S611A).
- the session key generation unit 224A of the recording device 200A generates a session key from the random number generated in step S608A and the random number received in step S605A (S612A).
- the data structure of the playback apparatus public key certificate in the second embodiment is the same as the data structure of the playback apparatus public key certificate in the first embodiment. Is omitted.
- the individualized title key generation unit 151A of the key distribution server 100A generates, for example, a 128-bit random number value as the individualized title key.
- the configuration is not limited to this.
- the key distribution server may generate the individualized title key by the following formula using the recording device ID included in the recording device public key certificate.
- AES_E (S, recording device ID
- AES_E (k, m) means that the input m is encrypted with the key k using AES encryption.
- S is a private key for generating an individualized title key.
- random number value means that the recording device ID and the random value are connected in this order.
- the recording device ID is, for example, a 32-bit numerical value
- the random value is, for example, 96 bits.
- a content decryption tool that decrypts a key obtains a common title key and an individualized title key and publishes them on a Web server, and obtains the public common title key and individualized title key and decrypts the encrypted content
- the key issuing authority obtains the content decryption tool, identifies the individualized title key published on the Web server, and identifies the recording device ID from the identified individualized title key by the following formula be able to.
- Recording device ID [AES_D (S, individualized title key)] upper 32 bits
- AES_D (k, c) means that the ciphertext c is decrypted with the key k using the AES decryption function.
- [X] upper 32 bits means that the upper 32 bits of x are extracted.
- the key issuing authority can specify the recording device ID from the individualized title key disclosed on the Web server, the key issuing authority can invalidate the recording device public key certificate including the specified recording device ID. Is possible.
- the content is divided into common content and individualized content, and the individualized content is encrypted using a different individualized title key for each recording process. And stored in the memory card.
- the content decryption tool that acquires the common title key and individualized title key and decrypts the encrypted content by obtaining the common title key and individualized title key and publishing them on the Web server is illegal. Even if sold, the individualized title key is different for each recording process or distribution process, making it difficult for an unspecified number of users to use the content decryption tool. This is because a plurality of encrypted contents (the same contents encrypted with a plurality of different individualized title keys) for the same contents are illegally used by an unspecified number of users using the content decryption tool. This is because it is necessary to obtain all the different individualized title keys for each recording process and publish them on the Web server. For this purpose, a malicious user needs to obtain all the individualized title keys that the user wants, which is very expensive.
- the unauthorized content recording tool pretends to be a regular recording device and records the encrypted provisional personalized content received from the key distribution server on the memory card without encrypting it with a personalized title key that is different for each memory card. It is a tool to do.
- the leaked recording device private key stored in the tool can be identified from the illegally sold unauthorized content recording tool, the identified recording device private key and the corresponding disclosure The key certificate can be revoked.
- a public key certificate revocation list (CRL) can be used as a method for revoking the recording device private key and the corresponding public key certificate.
- the memory card and the unauthorized content recording tool perform the authentication process shown in FIG.
- the recording device ID included in the recording device public key certificate received from the unauthorized content recording tool is the latest public key certificate certificate. If it is included in the application list (CRL), it is determined that the recording device public key certificate is invalid, and the subsequent processing is stopped.
- the key distribution server and the unauthorized content recording tool perform the authentication processing shown in FIG.
- the key distribution server verifies the recording device public key certificate in step 602A
- the recording device ID included in the recording device public key certificate received from the unauthorized content recording tool is the latest public key certificate. If it is included in the revocation list (CRL), it is determined that the recording device public key certificate is invalid, and the subsequent processing is stopped.
- CTL revocation list
- the public key certificate revocation list is information specifying a device to be revoked, specifically, a list of various device IDs and various device public keys, and a signature issued by the key issuing authority for this list. Consists of.
- the latest public key certificate revocation list (CRL) is: For example, it is distributed from a key distribution server to a regular recording device, recorded from a regular recording device to a regular memory card, and passed from the regular memory card to a regular playback device, so that the regular recording device and memory
- the card and the playback device can be configured to always hold the latest public key certificate revocation list (CRL).
- the common title key is different for each content.
- the key content distribution server side uses a common content key according to the number of distributions. May be changed. That is, the common content key may be changed every n times. Here, the ratio of n (example: 1000) is reduced with respect to the total number of distributions (example: 1 million). Further, the common content key may be changed every n hours.
- the content decryption tool that acquires the common title key and individualized title key and decrypts the encrypted content by obtaining the common title key and individualized title key and publishing them on the Web server is illegal. Even if sold, the common title key is different for each predetermined number of distribution processes, making it difficult for an unspecified number of users to use the content decryption tool.
- the individualized title key is different for each recording process or each distribution process, but is different for each predetermined number of recording processes or each distribution process. Also good. Moreover, you may combine the modification (1) and the modification (2).
- Embodiment 1 and Embodiment 2 RSA encryption is used for signature generation and signature verification in the generation of various public key certificates.
- the present invention is not limited to this. Any digital signature scheme can be used.
- the AES encryption is used for encryption and decryption of various keys and contents, but is not limited thereto. Any encryption method can be used.
- Each of the above devices (including a key issuing authority and a key distribution server) is specifically a computer system including a microprocessor, ROM, RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like. .
- a computer program is stored in the RAM or hard disk unit. Each device achieves its functions by the microprocessor operating according to the computer program.
- the computer program is configured by combining a plurality of instruction codes indicating instructions for the computer in order to achieve a predetermined function.
- Each device is not limited to a computer system including all of a microprocessor, a ROM, a RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like, and may be a computer system including a part of them. . (5) Part or all of the components constituting each of the above devices (including a key issuing authority and a key distribution server) are configured by one system LSI (Large Scale Integration). It is good.
- LSI Large Scale Integration
- the system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on a single chip, and specifically, a computer system including a microprocessor, ROM, RAM, and the like. .
- a computer program is stored in the RAM.
- the system LSI achieves its functions by the microprocessor operating according to the computer program.
- each part of the constituent elements constituting each of the above devices may be individually made into one chip, or may be made into one chip so as to include a part or all of them.
- the system LSI is used here, it may be called IC, LSI, super LSI, or ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible.
- An FPGA Field Programmable Gate Array
- a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.
- a part or all of the components constituting each of the above devices may be configured from an IC card that can be attached to and removed from each device or a single module.
- the IC card or the module is a computer system including a microprocessor, a ROM, a RAM, and the like.
- the IC card or the module may include the super multifunctional LSI described above.
- the IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.
- the present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of the computer program.
- the present invention also provides a computer-readable recording medium such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray Disc). ), Recorded in a semiconductor memory or the like.
- the digital signal may be recorded on these recording media.
- the computer program or the digital signal may be transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.
- the present invention may be a computer system including a microprocessor and a memory, the memory storing the computer program, and the microprocessor operating according to the computer program.
- the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like, and executed by another independent computer system. It is good.
- a recording system including a key distribution server, a recording device, and a recording medium device, wherein the key distribution server authenticates the recording medium device, and authentication by the authentication unit is successful.
- Media unique key receiving means for securely receiving a media unique key from a recording medium device, content dividing means for dividing content into common content and individualized content, and a first title key and a second title different for each content
- Title key generating means for generating a key, encryption means for encrypting the first title key and the second title key with the media unique key, and encrypting the common content with the first title key
- Transmitting means for transmitting the encrypted common content and the encrypted second title key to the recording medium device; and transmitting means for transmitting the encrypted individualized content to the recording device;
- the recording device includes: a receiving unit that receives the encrypted individualized content from a key distribution server; an authentication unit that authenticates
- Receiving means for receiving the title key, the encrypted common content, the encrypted second title key, and a decrypting means for decrypting the encrypted second title key using the media unique key A title key generating means for generating a third title key that differs for each recording process, an encryption means for encrypting the third title key with the media unique key, and the recording apparatus.
- the content is divided into common content and individualized content, and the individualized content is encrypted by the recording device using different individual title keys for each recording process or each distribution process. And stored in the memory card.
- the content decryption tool that acquires the common title key and individualized title key and decrypts the encrypted content by obtaining the common title key and individualized title key and publishing them on the Web server is illegal. Even if sold, the individualized title key is different for each recording process or distribution process, making it difficult for an unspecified number of users to use the content decryption tool. This is because a plurality of encrypted contents (the same contents encrypted with a plurality of different individualized title keys) for the same contents are illegally used by an unspecified number of users using the content decryption tool. This is because it is necessary to obtain all the different individualized title keys for each recording process and publish them on the Web server. For this purpose, a malicious user needs to obtain all the individualized title keys that the user wants, which is very expensive.
- the unauthorized content recording tool pretends to be a regular recording device and records the encrypted provisional personalized content received from the key distribution server on the memory card without encrypting it with a personalized title key that is different for each memory card. It is a tool to do. However, in this case, since the leaked recording device private key stored in the tool can be identified from the illegally sold unauthorized content recording tool, the identified recording device private key and the corresponding disclosure The key certificate can be revoked.
- a recording system composed of a key distribution server, a recording device, and a recording medium device, wherein the key distribution server records the authentication means for authenticating the recording medium device, and the authentication when the authentication means succeeds.
- Media unique key receiving means for securely receiving a media unique key from a medium device, content dividing means for dividing content into common content and individualized content, a first title key different for each content, and for each distribution process
- Title key generation means for generating a different third title key
- encryption means for encrypting the first title key and the third title key with the media unique key, and the common content as the first key
- Encryption means for encrypting with the title key
- authentication means for authenticating the recording device and when the authentication by the authentication means is successful, the recording device, Transmitting means for securely transmitting the three title keys and the individualized content; the encrypted first title key; the encrypted common content; and the encrypted third title key; Transmitting means for transmitting to the medium device, wherein the recording device authenticates the key distribution server, and if the authentication by the authentication means is successful, the recording device includes a third title key and an individual Receiving means for securely receiving the encrypted content; encryption means for encrypting the individualized content using the third title key; and transmitting means for
- a reproduction system including a recording medium device and a reproduction device, wherein the recording medium device includes a storage unit that stores a media unique key, an authentication unit that authenticates the reproduction device, and the authentication is successful.
- a transmission means for transmitting the encrypted individualized content and the playback device authenticates the recording medium device, and if the authentication is successful, the playback device receives a media unique key from the recording medium device.
- a receiving unit that securely receives the first title key encrypted from the recording medium device, the encrypted common content, the third title key encrypted, Receiving means for receiving the encoded individualized content; decrypting means for decrypting the encrypted first title key and the encrypted third title key using the media unique key; Decryption means for decrypting the encrypted common content using the decrypted first title key, and decryption means for decrypting the encrypted individualized content using the decrypted third title key And content combining means for combining the decrypted common content and the decrypted individualized content, and playback means for reproducing the combined content.
- a key distribution server used in a recording system including a key distribution server, a recording device, and a recording medium device, wherein the authentication unit authenticates the recording medium device, and the authentication by the authentication unit is successful.
- Media unique key receiving means for securely receiving a media unique key from a recording medium device, content dividing means for dividing content into common content and individualized content, and a first title key and a second title different for each content
- Title key generating means for generating a key
- a transmission means for transmitting the encrypted key content, the encrypted common content, and the encrypted second title key to the recording medium device, and a transmission for transmitting the encrypted individualized content to the recording device.
- a recording device used in a recording system including a key distribution server, a recording device, and a recording medium device, the receiving unit receiving the encrypted individualized content from the key distribution server, and a recording An authentication unit for authenticating the medium device, and a reception unit for securely receiving the second title key and the third title key from the recording medium device when the authentication by the authentication unit is successful, and the encrypted Decrypting means for decrypting the individualized content using the second title key, encryption means for encrypting the decrypted personalized content using the third title key, and the third title Transmitting means for transmitting the individualized content encrypted using the key to the recording medium device.
- a recording medium device used in a recording system including a key distribution server, a recording device, and a recording medium device, the storage unit storing the media unique key, and the unit authenticating the key distribution server;
- receiving means for receiving the encrypted second title key, and decrypting means for decrypting the encrypted second title key using the media unique key differ for each recording process
- a key distribution server used in a recording system including a key distribution server, a recording device, and a recording medium device, wherein the authentication unit authenticates the recording medium device, and the authentication by the authentication unit is successful.
- Media unique key receiving means for securely receiving the media unique key from the recording medium device, content dividing means for dividing the content into common content and individualized content, a first title key different for each content, and each distribution process
- Title key generating means for generating a different third title key
- encryption means for encrypting the first title key and the third title key with the media unique key, and the common content as the first key.
- An encryption means for encrypting with one title key, an authentication means for authenticating the recording device, and a record when authentication by the authentication means is successful Transmitting means for securely transmitting a third title key and individualized content to the device, the encrypted first title key, the encrypted common content, and the encrypted third title key Transmitting means for transmitting to the recording medium device.
- a recording device used in a recording system including a key distribution server, a recording device, and a recording medium device, wherein the authentication unit authenticates the key distribution server, and the authentication by the authentication unit is successful.
- a recording medium device used in a recording system including a key distribution server, a recording device, and a recording medium device, the storage unit storing the media unique key, and the unit authenticating the key distribution server; A transmission means for securely transmitting a media unique key to the key distribution server when the authentication is successful; the encrypted first title key; and the encrypted common content from the key distribution server.
- a recording medium device used in a reproduction system including a recording medium device and a reproduction device, the storage unit storing a media unique key, the means for authenticating the reproduction device, and the authentication succeeded
- a transmission unit that securely transmits the media unique key to the playback device, and an encrypted first title key, encrypted common content, and encrypted third title key.
- a playback device used in a playback system including a recording medium device and a playback device, the means for authenticating the recording medium device, and a media unique key from the recording medium device when the authentication is successful From the recording medium device, the encrypted first title key, the encrypted common content, the encrypted third title key, and the encrypted third title key
- Receiving means for receiving the individualized content decrypting means for decrypting the encrypted first title key and the encrypted third title key using the media unique key; Decrypting means for decrypting the encrypted common content using one title key, and decrypting the encrypted individualized content using the decrypted third title key
- a recording method comprising a key distribution server, a recording device, and a recording medium device, wherein the key distribution server records an authentication step for authenticating the recording medium device, and when authentication by the authentication means is successful
- a media unique key receiving step for securely receiving a media unique key from a media device, a content dividing step for dividing content into common content and individualized content, and a first title key and a second title key that differ for each content Generating a title key, encrypting the first title key and the second title key with the media unique key, and encrypting the common content with the first title key
- An encryption step, an encryption step for encrypting the individualized content with the second title key, and the encryption Transmitting the encrypted first title key, the encrypted common content, and the encrypted second title key to the recording medium device; and
- a transmitting step for transmitting to a recording device, wherein the recording device receives the encrypted individualized content from a key distribution server, an authentication step for authenticating the recording medium device, and the authentication step.
- the receiving step of securely receiving the second title key and the third title key from the recording medium device, and the encrypted individualized content as the second title key A decrypting step using the third title key, and a decrypting step decrypting using the third title key; Transmitting a personalized content encrypted using an ittle key to a recording medium device, wherein the recording medium device stores the media unique key and authenticates the key distribution server And a transmission step of securely transmitting a media unique key to a key distribution server when authentication by the authentication unit is successful, and the encrypted first title key, the encryption from the key distribution server Received common content, receiving step for receiving the encrypted second title key, decrypting step for decrypting the encrypted second title key, and generating a third title key different for each recording process Generating a title key, an encryption step for encrypting a third title key with the media unique key, and an authentication step for authenticating the recording device.
- a recording method comprising a key distribution server, a recording device, and a recording medium device, wherein the key distribution server records an authentication step for authenticating the recording medium device, and when authentication by the authentication means is successful
- a media unique key receiving step for securely receiving a media unique key from a media device, a content dividing step for dividing content into common content and individualized content, a first title key different for each content, and a distribution process
- An encryption step of encrypting with the title key of the image, an authentication step of authenticating the recording device, and authentication by the authentication means If successful, a transmission step of securely transmitting a third title key and individualized content to the recording device, the encrypted first title key, the encrypted common content, the encrypted content
- a transmission step of transmitting a third title key to the recording medium device wherein the recording device authenticates the key distribution
- Receiving the encrypted common content, the encrypted third title key from the recording device, respectively, and the received encrypted first title Storing each of the key, the encrypted common content, the encrypted third title key, and the encrypted individualized content.
- a playback method comprising a recording medium device and a playback device, wherein the recording medium device stores a media unique key, an authentication step for authenticating the playback device, and the authentication succeeds A secure transmission of the media unique key to the playback device, the encrypted first title key, the encrypted common content, the encrypted third title to the playback device.
- a secure receiving step, and from the recording medium device, the encrypted first title key, the encrypted common content, the encrypted content Receiving the received third title key, encrypted individualized content, and using the media unique key, the encrypted first title key, the encrypted third title
- a decrypting step for decrypting the key a decrypting step for decrypting the encrypted common content using the decrypted first title key; and the encrypted using the decrypted third title key
- Embodiments 1 and 2 are extracted and configured more simply will be described.
- the content division unit 102 of the key distribution server 100 divides the content into common content and individualized content. This is because the re-encryption is limited to the individualized content that is a part of the content in consideration that the processing load may become excessive if the entire content is re-encrypted.
- the processing load is a parameter that varies depending on the processing performance of the apparatus, the processing load is not considered in this embodiment. That is, the content is not divided and the entire content is re-encrypted.
- content may be divided in the same manner as in the first and second embodiments, and only individualized content may be re-encrypted.
- the content of the present embodiment is a part of the entire content and corresponds to the individualized content of the first and second embodiments.
- 6.1 Embodiment 3 The present embodiment corresponds to the first embodiment described above.
- FIG. 26 is a diagram showing a configuration of a recording / reproducing system 1001 according to an embodiment of the present invention.
- the recording / reproducing system 1001 includes a key distribution server 1002 that distributes content, various keys, and the like, a recording device 1003, and a recording medium device 1004.
- the key distribution server 1002, the recording device 1003, and the recording medium device 1004 correspond to the key distribution server 100, the recording device 200, and the recording medium device 300 in the first embodiment, respectively.
- the recording medium device 1004 is housed in a housing separate from the recording device 1003 and is detachable. However, the recording device 1003 and the recording medium device 1004 are housed in one housing (built-in). Type).
- the recording device 1003 may be configured to have all the configuration of the recording medium device 1004.
- the recording apparatus and the recording medium apparatus have no so-called integrated structure.
- FIG. 27 is a block diagram showing the configuration of the recording medium device 1004.
- the recording medium device 1004 includes holding means 1011, decryption means 1012, reception means 1013, authentication means 1014, title key generation means 1015, encryption means 1016 storage means 1017, and acquisition means 1018.
- the holding unit 1011 holds a media unique key 1021 that is shared between the recording medium device 1004 and the key distribution server 1002.
- the media unique key 1021 corresponds to the converted media unique key of the first embodiment.
- the key sharing method may be the same as that performed by the authentication unit 302 and the encryption unit 303 of the memory card 300 and the authentication unit 113 and the decryption unit 114 of the key distribution server 100 in the first embodiment.
- a known key sharing technique such as Diffie-Hellman key sharing may be used.
- the media unique key 1021 is a key that can be acquired only by a valid recording medium device. As described in the first embodiment, when the controller unique number, the controller key, etc. are valid, that is, a valid recording medium. Only the device can recover the key.
- the holding unit 1011 holds the media unique key 1021, but this is valid for the recording medium device 1004, and the media unique key 1021 has been successfully restored as described above. It is assumed that the holding means 1011 holds the above. In other words, if the recording medium device 1004 is invalid, the holding unit 1011 does not hold the media unique key.
- the receiving unit 1013 receives from the key distribution server 1002 the first title key encrypted with the common key 1021 and the common key.
- the first title key is a key used for content encryption / decryption at the time of content distribution or the like.
- the first title key is unique for each content.
- the first title key corresponds to the provisional title key of the first embodiment.
- the decrypting means 1012 decrypts the encrypted first title key with the media unique key 1021 and outputs it to the recording device 1003.
- Authentication unit 1014 performs mutual authentication with recording apparatus 1003.
- the authentication unit 1014 corresponds to the authentication unit 304 in the first embodiment.
- Mutual authentication processing is the same as in the first embodiment. Note that mutual authentication may be performed using another known protocol or the like.
- Title key generation means 1015 generates a second title key and outputs it to the recording apparatus 1003 when mutual authentication is successful.
- the title key generation unit 1015 generates a key different from the first title key when generating the key.
- the title key generation unit 1015 generates the generated key so that it does not overlap with the previously generated key as much as possible.
- the title key generation unit 1015 eventually generates a different second title key every time the content is encrypted or every time the content is recorded.
- a specific example of the second title key is a random number. If the generated second title key is the same as the first title key, the title key generation unit 1015 regenerates a random number until it generates a random number that has not been generated before, unlike the first title key. Shall. However, in reality, since the key length is limited, it may be difficult to continue to generate a key that has never been generated, but it is desirable to generate keys that do not overlap as much as possible.
- the second title key corresponds to the individualized title key of the first embodiment.
- the encryption unit 1016 encrypts the second title key with the media unique key 1021 and stores it in the storage unit 1017.
- the acquisition unit 1018 acquires the second encrypted content from the recording device 1003 and stores it in the storage unit 1017.
- the second encrypted content is generated by the recording device 1003 by decrypting the first encrypted content with the first title key and further encrypting with the second title key.
- FIG. 28 is a block diagram showing the configuration of the recording apparatus 1003.
- the recording device 1003 includes content receiving means 1031, key receiving means 1032, decryption means 1033, authentication means 1034, and encryption means 1035.
- the content receiving means 1031 receives the first encrypted content from the key distribution server 1002.
- Authentication unit 1034 performs mutual authentication with recording medium device 1004.
- the mutual authentication is performed in the same manner as the method performed in the first embodiment.
- the key receiving unit 1032 securely receives the first title key and the second title key from the recording medium device 1004 when the mutual authentication is successful.
- the key receiving unit 1032 corresponds to a part that realizes a function of receiving a key in the decrypting unit 206 and the decrypting unit 207 of the first embodiment.
- the technique for securely transmitting and receiving keys is performed in the same manner as in the first embodiment. Other known techniques may also be used.
- the decrypting unit 1033 decrypts the first encrypted content received by the content receiving unit 1031 with the first title key.
- the encryption unit 1035 generates a second encrypted content by encrypting the content decrypted by the decryption unit 1033 with the second title key, and stores the second encrypted content in the storage unit 1017 of the recording medium device 1004.
- FIG. 29 is a block diagram showing the configuration of the key distribution server 1002.
- the key distribution server 1002 includes media unique key holding means 1051, title key encryption means 1052, title key holding means 1053, content holding means 1054, and content encryption means 1055.
- the content holding unit 1054 holds content to be distributed.
- the title key holding unit 1053 holds a first title key that is associated with the content held by the content holding unit 1054 and used for encryption / decryption of the content.
- the media unique key holding unit 1051 holds a media unique key shared with the storage medium device 1004.
- the key sharing method may be the same as that performed by the authentication unit 302 and the encryption unit 303 of the memory card 300 and the authentication unit 113 and the decryption unit 114 of the key distribution server 100 in the first embodiment.
- the key distribution server 1002 does not transmit the first title key encrypted by the unauthorized media unique key when the shared media unique key is an unauthorized key such as exposed. And Whether or not the media unique key is illegal can be confirmed by a known technique, for example, using the above-mentioned CRL.
- Title key encryption means 1052 encrypts the first title key with a media unique key and outputs it to the recording medium device 1004.
- the content encryption unit 1055 encrypts the content with the first title key and stores it in the storage unit 1017 of the recording medium device 1004.
- FIG. 30 is a flowchart showing an operation during distribution / recording according to the present embodiment.
- the key distribution server 1002 receives a content distribution request from the recording device 1003 and starts distribution processing.
- the content encryption unit 1055 of the key distribution server 1002 reads the content from the content holding unit 1054, reads the first title key from the title key holding unit, encrypts the content with the first title key, and encrypts the content. Is transmitted to the recording apparatus 1003 (S1001).
- the title key encryption unit 1052 of the key distribution server 1002 reads the first title key from the title key holding unit 1053, encrypts the first title key with the media unique key, and stores the storage unit of the recording medium device 1004. It is stored in 1017 (S1002).
- the authentication unit 1034 of the recording device 1003 and the authentication unit 1014 of the recording medium device 1004 Perform mutual authentication (S1003).
- the decryption means 1012 in the recording medium device 1004 decrypts the encrypted first title key with the media unique key 1021 (S1005) and securely outputs it to the recording device 1003. (S1006). Then, the title key generation unit 1015 in the recording medium device 1004 generates the second title key (S1007), and securely outputs the second title key to the recording device 1003 (S1008).
- the key receiving means 1032 acquires the first title key and the second title key output from the recording medium device 1004 (S1006, S1006). S1008). Then, the decryption unit 1033 decrypts the encrypted content with the first title key (S1022).
- the encryption unit 1035 of the recording device 1003 encrypts the decrypted plaintext content with the second title key and stores it in the storage unit 1017 of the recording medium device 1004 (S1023).
- the encryption unit 1016 of the recording medium device 1004 encrypts the second title key with the media unique key 1021, and uses the encrypted second title key.
- the data is stored in the storage unit 1017 of the storage medium device 1004 (S1009).
- the first encrypted content distributed from the key distribution server to the recording device is once decrypted with the first title key decrypted by the recording medium device with a high security level, and the second title key is used. Encrypted.
- the second title key is generated by the recording medium device and is different for each recording process. Therefore, even if a title key distribution attack in which the first title key, which is a key for decrypting the first encrypted content, is disclosed to the malicious user and disclosed, is performed, the second encryption stored in the recording medium device The content cannot be decrypted with the published first title key. Therefore, it is possible to prevent content from being illegally used due to a title key distribution attack.
- this content is also encrypted in the other recording medium device with a different second title key for each recording process. Will be recorded. Therefore, even in this case, the content is not illegally used by the title key distribution attack.
- the recording / playback system 1001 may include a playback device that plays back content recorded on a recording medium device.
- FIG. 31 is a block diagram showing a configuration of the playback apparatus 1005 according to the present embodiment.
- a playback apparatus 1005 corresponds to the playback apparatus 400 in the first embodiment.
- the playback device 1005 includes an acquisition unit 1091, a title key decryption unit 1092, a content decryption unit 1093, and a playback unit 1094.
- the obtaining unit 1091 obtains the media unique key 1021, the encrypted second title key, and the content encrypted by the second title key from the recording medium device 1004.
- Title key decryption means 1092 decrypts the encrypted second title key using the media unique key 1021.
- Content decrypting means 1093 decrypts the content encrypted with the second title key, using the second title key.
- Reproduction means 1094 reproduces the decrypted content.
- FIG. 32 shows an operation of processing in which the playback device 1005 plays back the content recorded in the recording medium device 1004.
- the acquisition unit 1091 acquires the media unique key 1021 held in the holding unit 1011 of the recording medium device 1004, and acquires the encrypted second title key recorded in the storage unit 1017 (S1101). .
- Title key decryption means 1092 decrypts the encrypted second title key with the media unique key (S1102).
- the content decryption means 1093 reads the encrypted content from the storage means 1017 of the recording medium device 1004 (S1103) and decrypts it with the second title key (S1104).
- the playback unit 1094 plays back the content (S1105).
- the second title is generated by the title key generation unit 1015 of the recording medium device 1004. This is because it is desirable to generate the second title key with a secure device in consideration of the security level. That is, a recording medium device configured with an SD card or the like as an example generally has a higher secure level than a recording device configured with a general-purpose personal computer or the like as an example.
- FIG. 33 is a diagram showing a configuration of a recording / reproducing system according to an embodiment of the present invention.
- the recording / playback system includes a key distribution server 1201, a recording device 1202, and a recording medium device 1203 that distribute contents, various keys, and the like.
- the key distribution server 1201, the recording device 1202, and the recording medium device 1203 correspond to the key distribution server 100A, the recording device 200A, and the recording medium device 300A in the second embodiment, respectively.
- the recording medium device 1203 is housed in a separate housing from the recording device 1202 and is configured to be detachable. However, the recording device 1203 and the recording medium device 1202 are housed in one housing (so-called “so-called”). , An integrated configuration).
- FIG. 34 is a block diagram showing the configuration of the key distribution server 1201.
- the key distribution server 1201 It includes media unique key holding means 1321, title key holding means 1322, authentication means 1323, title key generation means 1324, title key encryption means 1325, content holding means 1326, and content encryption means 1327.
- the media unique key holding unit 1321 holds the media unique key 1025.
- the media unique key is the same key as the media unique key 1021 of the third embodiment.
- the title key holding means 1322 holds the first title key.
- the first title key is the same as that in the third embodiment.
- Authentication unit 1323 performs mutual authentication with recording device 1202.
- Authentication unit 1323 corresponds to authentication unit 153A in the second embodiment.
- the mutual authentication process is the same as in the second embodiment. Note that mutual authentication may be performed using another known protocol or the like.
- the title key generating unit 1324 generates a second title key when the mutual authentication in the authenticating unit 1323 is successful, and securely outputs it to the recording device 1202.
- the title key generating unit 1324 generates a key different from the first title key when generating the key.
- the title key generating unit 1324 when generating the second title key a plurality of times, the title key generating unit 1324 generates the generated key so that it does not overlap with the previously generated key as much as possible.
- the title key generating unit 1324 eventually generates a different second title key each time content is distributed, every time content is encrypted, or every time content is recorded. Details of the second title key are the same as those described in the third embodiment.
- the title key encryption unit 1325 encrypts the first title key with the media unique key and transmits it to the recording medium device 1203.
- the first title key encrypted with the media unique key is referred to as an encrypted first title key.
- the content holding unit 1326 holds content to be distributed.
- the content encryption unit 1327 encrypts the content using the first title key and transmits the content to the recording medium device 1203.
- the encrypted content is referred to as first encrypted content.
- FIG. 35 is a block diagram showing the configuration of the recording apparatus 1202.
- the recording device 1202 includes an authentication unit 1301, a decryption unit 1302, and an encryption unit 1303.
- Authentication unit 1301 performs mutual authentication with key distribution server 1321.
- the decryption means 1302 receives the first encrypted content and the second title key from the key distribution server 1201 when the mutual authentication is successful. Also, the first title key is received from the recording medium device 1203.
- the first encrypted content is decrypted with the first title key.
- the encryption unit 1303 encrypts the content decrypted by the decryption unit 1302 with the second title key and transmits it to the recording medium device 1203.
- the content encrypted by the encryption unit 1303 is referred to as a second encrypted content.
- FIG. 36 is a block diagram showing the configuration of the recording medium device 1203.
- the recording medium device 1203 includes a holding unit 1341, a decrypting unit 1342, an encrypting unit 1343, and a storage unit 1344.
- the holding unit 1341 holds a media unique key shared between the key management server 1201 and the recording medium device 1203.
- the media unique key is the same key as the media unique key 1201 of the first embodiment.
- the decrypting means 1342 acquires the encrypted first title key from the key distribution server 1201 and decrypts it using the media unique key. The decrypted first title key is transmitted to the recording device 1202.
- the encryption unit 1343 securely obtains the second title key from the key distribution server 1201, encrypts it with the media unique key, and securely holds it in the storage unit 1344.
- the second title key encrypted with the media unique key is called a second encrypted title key.
- FIG. 37 is a flowchart showing the operation of the content distribution system of this embodiment.
- the key distribution server 1201 receives a content distribution request from the recording device 1202 and starts distribution processing.
- the title key generation unit 1324 of the key distribution server 1201 generates a second title key (S1303).
- the content encryption unit 1327 encrypts the content with the first title key using the common key encryption (S1304).
- the first encrypted content and the second title key are securely transmitted to the recording device 1202.
- the decryption unit 1302 of the recording device 1202 receives the first encrypted content and the second title key from the key distribution server 1201 when the mutual authentication of S1301 is successful (S1321: YES). Then, the first title key is received from the recording medium device 1203 (S1322). However, although not shown in FIG. 37, a separate authentication process is performed between the recording device 1202 and the recording medium device 1203 prior to transmission / reception of the first title key between the recording device 1202 and the recording medium device 1203. It may be performed only when authentication is successful.
- the decrypting means 1342 of the recording device 1202 decrypts the first encrypted content using the first title key (S1323). Then, the encryption unit 143 of the recording device 1202 encrypts the content decrypted in S1323 with the second title key (S1324), and the second encrypted content that is the encrypted content is stored in the recording medium device 1203. 1344 is written (S1325).
- the title key generating unit 1324 securely transmits the second title key to the recording medium device 1203 (S1306).
- the encryption unit 1343 of the recording medium device 1203 encrypts the second title key with the media unique key and securely stores it in the storage unit 1344 (S1326). (effect)
- the first encrypted content distributed from the key distribution server to the recording device is once decrypted with the first title key decrypted by the recording medium device with a high security level, and the second title key is used. Encrypted.
- the second title key is generated by a key distribution server, and is a key that is different for each distribution process.
- the content is also generated in the other recording medium device by the key distribution server and is different for each distribution process. It will be recorded after being encrypted with the two title keys. Therefore, even in this case, the content is not illegally used by the title key distribution attack.
- the content distribution system of the present embodiment may include a playback device that plays back the content recorded on the recording medium device.
- the playback device may be the same as that described in the third embodiment.
- the authentication means 1014, 1034, 1301, and 1321 may be deleted from the configuration. In this case, it is desirable to secure a desired security level by another method.
- data that is not described in the third and fourth embodiments is authenticated only when authentication is performed between the devices prior to data transmission / reception and authentication is successful. It is good also as transmitting / receiving.
- the recording device may mediate transmission / reception of data between the key distribution server and the recording medium device.
- Each of the above devices is specifically a computer system including a microprocessor, ROM, RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like.
- a computer program is stored in the RAM or the hard disk unit.
- Each device achieves its function by the microprocessor operating according to the computer program.
- the computer program is configured by combining a plurality of instruction codes indicating instructions for the computer in order to achieve a predetermined function.
- each device is not limited to a computer system including all of a microprocessor, a ROM, a RAM, a hard disk unit, a display unit, a keyboard, a mouse, and the like, but may be a computer system including a part thereof.
- a part or all of the constituent elements constituting each of the above devices is configured by a circuit that realizes the function of the constituent element, or a program that realizes the function of the constituent element and a processor that executes the program Alternatively, it may be configured from one system LSI (Large Scale Integration).
- the system LSI is a super multifunctional LSI manufactured by integrating a plurality of components on one chip, and specifically, a computer system including a microprocessor, a ROM, a RAM, and the like. .
- a computer program is stored in the RAM.
- the system LSI achieves its functions by the microprocessor operating according to the computer program. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.
- system LSI Although the system LSI is used here, it may be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
- the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor.
- An FPGA Field Programmable Gate Array
- a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.
- a part or all of the constituent elements constituting each of the above devices may be configured by an IC card or a single module that can be attached to and detached from each device.
- the IC card or the module is a computer system including a microprocessor, a ROM, a RAM, and the like.
- the IC card or the module may include the super multifunctional LSI described above.
- the IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.
- the present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of the computer program.
- the present invention also provides a computer-readable recording medium such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray Disc). ), Recorded in a semiconductor memory or the like. Further, the present invention may be the computer program or the digital signal recorded on these recording media.
- the computer program or the digital signal may be transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.
- the program or the digital signal is recorded on the recording medium and transferred, or the program or the digital signal is transferred via the network or the like, and is executed by another independent computer system. It is good.
- the recording system according to the present invention is useful as a system that prevents the digital content recorded on the recording medium from being copied and reproduced on another recording medium while protecting the rights of the copyright holder of the digital content. is there.
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Abstract
Description
・記録媒体に、当該記録媒体固有の書き替え不可能な一意のメディアIDを格納し、
・再生装置に、署名検証用公開鍵と、当該再生装置固有のデバイス鍵を格納し、
・コンテンツ配信サーバに、メディア鍵と、暗号化メディア鍵ブロック(Media Key Block(MKB))を格納し、ここで、前記暗号化メディア鍵ブロックは、各再生装置に格納するデバイス鍵をそれぞれ用いて、メディア鍵を暗号化した、暗号化メディア鍵を含むように構成し
・コンテンツ配信サーバは、コンテンツ毎に固有のタイトル鍵を生成し、タイトル鍵を用いてコンテンツを暗号化して暗号化コンテンツを生成し、メディア鍵を用いてタイトル鍵を暗号化して暗号化タイトル鍵を生成し、
・コンテンツ配信サーバは、ユーザからのコンテンツ購入要求に対応して、課金処理を行った後、前記署名生成用公開鍵に対応する署名生成用秘密鍵を用いて、ユーザの記録媒体のメディアIDに対する署名を生成し、この署名と、暗号化メディア鍵ブロックと、暗号化タイトル鍵と、暗号化コンテンツを、ユーザに配信し、
・ユーザの記録装置は、記録媒体に、受信したメディアIDの署名と、暗号化メディア鍵ブロックと、暗号化タイトル鍵と、暗号化コンテンツを格納し、
・ユーザの再生装置は、署名検証用公開鍵と、記録媒体のメディアIDを用いて、メディアIDの署名を検証し、検証に成功すれば、格納されているデバイス鍵を用いて、記録媒体から読み出した前記暗号化メディア鍵ブロックに含まれる暗号化メディア鍵を復号し、復号されたメディア鍵を用いて暗号化タイトル鍵を復号し、復号されたタイトル鍵を用いて暗号化コンテンツを復号し、復号されたコンテンツを再生する。
・コンテンツ配信サーバに、更新されたメディア鍵と、更新された暗号化メディア鍵ブロック(Media Key Block(MKB))を格納する。ここで、更新された暗号化メディア鍵ブロックは、以下の手順で生成する。
・更新されたメディア鍵を生成し、特定されたデバイス鍵を除く、他の正規の再生装置に格納されているデバイス鍵をそれぞれ用いて、前記更新されたメディア鍵を暗号化して、暗号化メディア鍵を生成し、生成された暗号化メディア鍵を含む、更新された暗号化メディア鍵ブロックを生成する。このように、更新された暗号化メディア鍵ブロックを生成することで、更新された暗号化メディア鍵ブロックを、コンテンツ復号ツールに組み込まれたデバイス鍵で復号しようとしても、正しい更新されたメディア鍵を生成できない。
・コンテンツ配信サーバは、前記更新されたメディア鍵でタイトル鍵を暗号化し、更新された暗号化タイトル鍵を生成し、
・コンテンツ配信サーバは、ユーザからのコンテンツ購入要求に対応して、課金処理を行った後、ユーザの記録媒体のメディアIDに対する署名と、更新された暗号化メディア鍵ブロック、更新された暗号化タイトル鍵、及び、暗号化コンテンツを、ユーザに配信する。
以下本発明の実施の形態について、図面を参照しながら説明する。
1.実施の形態1
以下、本発明に係る実施の形態1について、図面を参照しながら説明する。
1.1 全体構成
図1は、本発明の実施の形態1における記録再生システムの全体構成を示す図である。記録再生システムは、鍵配信サーバ100と、記録装置200と、記録媒体装置300と、再生装置400、及び、鍵発行局900で構成される。以下では、記録媒体装置300がメモリカードの場合について説明する。
1.2 鍵発行局900の詳細構成
図2に示すように、鍵発行局900は、ルート公開鍵生成部901、コントローラID格納部902、部分メディアID生成部903、記録媒体装置公開鍵生成部904、メディア固有鍵生成部905、記録媒体装置秘密鍵生成部906、装置識別情報生成部907、記録装置・再生装置・鍵配信サーバ公開鍵生成部908、記録装置・再生装置・鍵配信サーバ秘密鍵生成部909、ルート秘密鍵生成部910、記録媒体装置公開鍵証明書生成部911、コントローラ鍵格納部912、暗号化部913、記録装置・再生装置・鍵配信サーバ公開鍵証明書生成部914からなる。
部分メディアID生成部903は、部分メディアIDを生成する。部分メディアIDのビット長は、例えば、64ビットとする。なお、後述するように、部分メディアIDとコントローラIDは連結され、記録媒体装置を一意に特定するための識別情報であるメディアIDを構成する。即ち
メディアID=コントローラID||部分メディアID
ここで、x||yは、xとyをこの順に連結することを意味する。メディアIDのビット長は例えば128ビットである。
1.3 鍵配信サーバ100の詳細の構成
図3に示すように、鍵配信サーバ100は、コンテンツ格納部101、コンテンツ分割部102、コンテンツ区別情報生成部103、鍵配信サーバ秘密鍵格納部104、鍵配信サーバ公開鍵証明書格納部105、共通タイトル鍵生成部106、共通コンテンツ格納部107、暫定タイトル鍵生成部108、個別化コンテンツ格納部109、暗号化部110、暗号化部111、ルート公開鍵格納部112、認証部113、復号部114、暗号化部115、暗号化部116から構成される。
1.4 記録装置200の詳細の構成
図4に示すように、記録装置200は、記録媒体装置秘密鍵格納部201、記録装置公開鍵証明書格納部202、復号部203、ルート公開鍵格納部204、認証部205、復号部206、復号部207、暗号化部208から構成される。
復号部203は、復号部206が生成した暫定タイトル鍵を用いて、鍵配信サーバ100から受信した暗号化暫定個別化コンテンツを復号し、個別化コンテンツを生成する。
復号部206は、認証部205が生成したセッション鍵を用いて、メモリカード300から受信した暗号化暫定タイトル鍵を復号し、暫定タイトル鍵を生成する。
復号部207は、認証部205が生成したセッション鍵を用いて、メモリカード300から受信した暗号化個別化タイトル鍵を復号し、個別化タイトル鍵を生成する。
1.5 メモリカード300の詳細の構成
図5に示すように、メモリカード300は、コントローラ330と、メモリ部340とから構成される。ここで、コントローラは、メモリカード300のメモリ部340に対するデータの読み出し/書き込み等の処理を行うとともに、鍵配信サーバ100、記録装置200及び再生装置400からの要求に応じて、相互認証処理やデータの送受信処理等を行う。コントローラ330は、LSI等の半導体デバイス、メモリ部340は、例えば、フラッシュメモリで構成される。
暗号化個別化コンテンツ格納部324は、記録装置200から受信した暗号化個別化コンテンツを格納する。
ここで、暗号化部305、306、及び、317、復号部310、315、及び、316にて用いる暗号化アルゴリズムとしては、例えば、AES(Advanced Encryption Standard)暗号を用いることができる。AES暗号については、公知であるので、説明を省略する。
1.6 再生装置400の詳細の構成
図6に示すように、再生装置400は、ルート公開鍵格納部401、認証部402、復号部403、復号部404、復号部405、復号部406、復号部407、再生装置秘密鍵格納部408、再生装置証明書格納部409から構成される。
1.7 認証部の詳細構成
図7に、鍵配信サーバの認証部113と、メモリカードの認証部302の詳細構成の一例を示す。
ここで、AES_E(k,m)は、AES暗号で、鍵kで入力mを暗号化することを意味する。また、A(+)Bは、AとBの排他的論理和演算を意味する。
ここで、kは、予めセッション鍵生成部に秘密に格納されている秘密パラメータ、乱数1は、乱数生成部が生成した乱数、乱数2は、メモリカードから受信した乱数である。
署名検証部332は、ルート公開鍵と、鍵配信サーバから受信した鍵配信サーバ公開鍵証明書を用いて、鍵配信サーバ公開鍵証明書に含まれる署名を検証し、署名検証が成功すれば、鍵配信サーバ公開鍵証明書に含まれる鍵配信サーバ公開鍵が正当なものとみなす。
ここで、kは、予めセッション鍵生成部に秘密に格納されている秘密パラメータ、乱数1は、鍵配信サーバから受信した乱数、乱数2は、乱数生成部335が生成した乱数である。
記録装置の認証部205と、再生装置の認証部402の詳細構成は、鍵配信サーバの認証部113、の詳細構成と同様の構成であるので、説明は省略する。
1.8 コンテンツ配信・記録時の動作詳細フロー
鍵配信サーバ100から、記録装置200を介して、メモリカード300にコンテンツを配信、記録する際の動作詳細フローの一例を、図8から図10に示す。
ここで、AES_E(k,m)は、AES暗号で、鍵kで入力mを暗号化することを意味する。また、A(+)Bは、AとBの排他的論理和演算を意味する。
ここで、AES_E(k,m)は、AES暗号を用いて、鍵kで入力mを暗号化することを示す。
1.9 鍵配信サーバとメモリカード間の認証処理の詳細動作フロー
図11に鍵配信サーバとメモリカード間の認証処理の詳細動作フローを示す。
1.10 記録装置とメモリカード間の認証処理の詳細動作フロー
図12に記録装置とメモリカード間の認証処理の詳細動作フローを示す。
1.11 記録媒体装置公開鍵証明書、鍵配信サーバ公開鍵証明書、記録装置公開鍵証明書のデータ構成
図17(a)に、記録媒体装置公開鍵証明書のデータ構成の一例を示す。図17(a)に示すように、記録媒体装置公開鍵証明書は、コントローラID、部分メディアID、及び、記録媒体装置公開鍵と、署名から構成される。ここで、署名は、ルート秘密鍵を用いて、コントローラIDと部分メディアIDと記録媒体装置公開鍵を連結したものに対して、例えば、下記の式で生成される。
ここで、s=RSA_SIGN(k,m)は、RSA署名生成関数を用いて、秘密鍵kで、入力mに対する署名sを生成することを意味する。RSA署名生成関数は公知であるので説明を省略する。
ここで、m=RSA_VRFY(p,s)は、RSA署名検証関数を用いて、公開鍵pで、mに対する署名sを検証することを意味する。RSA署名検証関数については公知であるので説明を省略する。
ここで、鍵配信サーバIDは、例えば、32ビットの数値である。
また、この署名は、以下の式で署名検証される。
{鍵配信サーバID||鍵配信サーバ公開鍵}=RSA_VRFY(ルート公開鍵、署名)
図17(c)に記録装置公開鍵証明書のデータ構成の一例を示す。図17(c)に示すように、記録装置公開鍵証明書は、記録装置を一意に識別するための情報である記録装置ID、及び、記録装置公開鍵と、署名から構成される。ここで、記録装置IDは、さらに、記録装置か再生装置かを示す装置種別情報、記録装置製造者を一意に識別するための記録装置製造者ID、及び、各記録装置の個体を識別するための記録装置シリアル番号で構成される。
ここで、記録装置IDは、例えば、32ビットの数値である。
{記録装置ID||記録装置公開鍵}=RSA_VRFY(ルート公開鍵、署名)
1.12 コンテンツ再生時の動作詳細フロー
メモリカード300に記録されたコンテンツを再生装置で再生する際の動作詳細フローの一例を、図13から図14に示す。
ここで、AES_E(k,m)は、AES暗号で、鍵kで入力mを暗号化することを意味する。また、A(+)Bは、AとBの排他的論理和演算を意味する。
ここで、AES_E(k,m)は、AES暗号を用いて、鍵kで入力mを暗号化することを示す。また(+)は、排他的論理和演算である。
再生装置400の復号部404が、受信した暗号化共通タイトル鍵を、ステップS408で生成した変換後メディア固有鍵で復号し、共通タイトル鍵を生成する(S410)。
1.13 再生装置とメモリカード間の認証処理の詳細動作フロー
図15に再生装置400とメモリカード300間の認証処理の詳細動作フローを示す。
1.14 再生装置公開鍵証明書のデータ構成
図17(d)に再生装置公開鍵証明書のデータ構成の一例を示す。図17(d)に示すように、再生装置公開鍵証明書は、再生装置を一意に識別するための情報である再生装置ID、及び、再生装置公開鍵と、署名から構成される。ここで、再生装置IDは、さらに、記録装置か再生装置かを示す装置種別情報、再生装置製造者を一意に識別するための再生装置製造者ID、及び、各再生装置の個体を識別するための再生装置シリアル番号で構成される。
ここで、再生装置IDは、例えば、32ビットの数値である。
{再生装置ID||再生装置公開鍵}=RSA_VRFY(ルート公開鍵、署名)
1.15 変形例
(1)個別化タイトル鍵
実施の形態1では、メモリカード300の個別化タイトル鍵生成部313が、個別化タイトル鍵として、例えば、128ビットの乱数値を生成するとしたが、この構成には限定されない。
ここで、AES_E(k、m)は、AES暗号を用いて、鍵kで入力mを暗号化することを意味する。また、記録装置ID||乱数値は、記録装置IDと乱数値をこの順で連結することを意味する。ここで、記録装置IDは、例えば、32ビットの数値であり、乱数値は、例えば、96ビットとする。上記式により、128ビットのランダムな個別化タイトル鍵が得られる。
ここで、AES_D(k、c)は、AES復号関数を用いて、鍵kで暗号文cを復号することを意味する。また[x]上位32ビットは、xの上位32ビットを抽出することを意味する。
2.実施の形態2
以下、本発明に係る実施の形態2について、図面を参照しながら説明する。
2.1 全体構成
本発明の実施の形態2における記録再生システムの全体構成は、実施の形態1と同じであり、記録再生システムは、鍵配信サーバ100Aと、記録装置200Aと、記録媒体装置300Aと、再生装置400A、及び、鍵発行局900Aで構成される。
2.2 鍵発行局900Aの詳細構成
鍵発行局900Aの構成は、実施の形態1の鍵発行局900と全く同じである。このため説明は省略する。
2.3 鍵配信サーバ100Aの詳細の構成
図19に示すように、鍵配信サーバ100Aは、コンテンツ格納部101A、コンテンツ分割部102A、コンテンツ区別情報生成部103A、鍵配信サーバ秘密鍵格納部104A、鍵配信サーバ公開鍵証明書格納部105A、共通タイトル鍵生成部106A、共通コンテンツ格納部107A、個別化タイトル鍵生成部151A、個別化コンテンツ格納部109A、暗号化部110A、ルート公開鍵格納部112A、認証部113A、復号部114A、暗号化部115A、暗号化部152A、認証部153A、暗号化部154A、暗号化部155Aから構成される。
2.4 記録装置200Aの詳細の構成
図20に示すように、記録装置200Aは、記録媒体装置秘密鍵格納部201A、記録装置公開鍵証明書格納部202A、ルート公開鍵格納部204A、認証部251A、復号部252A、復号部253A、暗号化部254Aから構成される。
2.5 メモリカード300Aの詳細の構成
図21に示すように、メモリカード300Aは、コントローラ330Aと、メモリ部340Aとから構成される。ここで、コントローラは、メモリカード300Aのメモリ部340Aに対するデータの読み出し/書き込み等の処理を行うとともに、鍵配信サーバ100A、記録装置200A及び再生装置400Aからの要求に応じて、相互認証処理やデータの送受信処理等を行う。コントローラ330Aは、LSI等の半導体デバイス、メモリ部340Aは、例えば、フラッシュメモリで構成される。
2.6 再生装置400Aの詳細の構成
再生装置400Aの構成は、実施の形態1の再生装置400と全く同じである。このため説明は省略する。
2.7 認証部の詳細構成
図22に、鍵配信サーバの認証部153Aと、記録装置の認証部251Aの詳細構成の一例を示す。
2.8 コンテンツ配信・記録時の動作詳細フロー
鍵配信サーバ100Aから、記録装置200Aを介して、メモリカード300Aにコンテンツを配信、記録する際の動作詳細フローの一例を、図23から図24に示す。
ここで、AES_E(k,m)は、AES暗号で、鍵kで入力mを暗号化することを意味する。また、A(+)Bは、AとBの排他的論理和演算を意味する。
次に、復号部315Aが、暗号化記録媒体装置秘密鍵格納部318Aが格納する暗号化記録媒体装置秘密鍵を、ステップS101Aで生成したコントローラ固有鍵で復号し、記録媒体装置秘密鍵を生成する(S102A)。
ここで、AES_E(k,m)は、AES暗号を用いて、鍵kで入力mを暗号化することを示す。
2.9 鍵配信サーバとメモリカード間の認証処理の詳細動作フロー
鍵配信サーバ100Aとメモリカード300A間の認証処理の詳細動作フローは、実施の形態1の鍵配信サーバ100とメモリカード300間の認証処理の詳細動作フローと全く同じであるため説明は省略する。
2.10 鍵配信サーバと記録装置間の認証処理の詳細動作フロー
図25に、鍵配信サーバと記録装置間の認証処理の詳細動作フローを示す。
記録装置200Aは、鍵配信サーバ100Aに、記録装置公開鍵証明書を送信する(S601A)。
2.11 記録媒体装置公開鍵証明書、鍵配信サーバ公開鍵証明書、記録装置公開鍵証明書のデータ構成
実施の形態2における記録媒体装置公開鍵証明書、鍵配信サーバ公開鍵証明書、及び、記録装置公開鍵証明書のデータ構成は、実施の形態1における、記録媒体装置公開鍵証明書、鍵配信サーバ公開鍵証明書、及び、記録装置公開鍵証明書のデータ構成と同じであるので、説明は省略する。
2.12 コンテンツ再生時の動作詳細フロー
実施の形態2における、メモリカード300Aに記録されたコンテンツを再生装置400Aで再生する際の動作詳細フローは、実施の形態1における、メモリカード300に記録されたコンテンツを再生装置400で再生する際の動作詳細フローと同じであるので説明を省略する。
2.13 再生装置とメモリカード間の認証処理の詳細動作フロー
実施の形態2における、再生装置400Aとメモリカード300A間の認証処理の詳細動作フローは、実施の形態1における再生装置400とメモリカード300間の認証処理の詳細動作フローと同じであるので説明を省略する。
2.14 再生装置公開鍵証明書のデータ構成
実施の形態2における再生装置公開鍵証明書のデータ構成は、実施の形態1における、再生装置公開鍵証明書のデータ構成と同じであるので、説明は省略する。
2.15 変形例
(1)個別化タイトル鍵
実施の形態2では、鍵配信サーバ100Aの個別化タイトル鍵生成部151Aが、個別化タイトル鍵として、例えば、128ビットの乱数値を生成するとしたが、この構成には限定されない。
ここで、AES_E(k、m)は、AES暗号を用いて、鍵kで入力mを暗号化することを意味する。また、Sは、個別化タイトル鍵生成用秘密鍵である。また、記録装置ID||乱数値は、記録装置IDと乱数値をこの順で連結することを意味する。ここで、記録装置IDは、例えば、32ビットの数値であり、乱数値は、例えば、96ビットとする。上記式により、128ビットのランダムな個別化タイトル鍵が得られる。
ここで、AES_D(k、c)は、AES復号関数を用いて、鍵kで暗号文cを復号することを意味する。また[x]上位32ビットは、xの上位32ビットを抽出することを意味する。
3 まとめ
実施の形態1、及び、実施の形態2の構成により、コンテンツが共通コンテンツと個別化コンテンツに分割され、さらに、個別化コンテンツは、記録処理毎に異なる個別化タイトル鍵を用いて暗号化され、メモリカードに格納される。
鍵発行局生成の署名=RSA_SIGN(ルート秘密鍵、各種装置ID及び各種装置公開鍵のリスト)最新の公開鍵証明書リボケーションリスト(CRL)は、例えば、鍵配信サーバから、正規の記録装置に配信され、正規の記録装置から、正規のメモリカードに記録され、正規のメモリカードから正規の再生装置に渡されることにより、正規の記録装置、メモリカード、及び、再生装置に、常に最新の公開鍵証明書リボケーションリスト(CRL)が保持されるように構成することができる。
4 変形例
(1)実施の形態1、及び、実施の形態2では、共通タイトル鍵を、コンテンツ毎に異なるものとしたが、例えば、鍵会配信サーバ側にて配信数に応じて共通コンテンツ鍵を変えても良い。即ちn回配信するごとに共通コンテンツ鍵を変えても良い。ここで、総配信数(例:100万)に対してn(例:1000)の比率が低くする。また、n時間毎に共通コンテンツ鍵を変えても良い。このとき、悪意のあるユーザが、正規の再生装置から、再生装置秘密鍵などを不正に入手し、正規再生装置を装って、メモリカードから受信した暗号化共通タイトル鍵及び暗号化個別化タイトル鍵を復号して、共通タイトル鍵及び、個別化タイトル鍵を入手しWebサーバで公開する一方、公開された共通タイトル鍵及び個別化タイトル鍵を取得して暗号化コンテンツを復号するコンテンツ復号ツールを不正に販売したとしても、所定数の配信処理毎に、共通タイトル鍵が異なるため、不特定多数のユーザに、前記コンテンツ復号ツールを利用させることは困難となる。なぜなら、不特定多数のユーザに対して、同一のタイトルの暗号化コンテンツを、前記コンテンツ復号ツールを用いて不正に復号させるためには、所定数の配信処理毎に、異なる共通タイトル鍵を全て入手し、Webサーバで公開する必要があるためである。このためには、悪意のあるユーザは、ユーザが求める全ての個別化タイトル鍵を入手する必要があり、莫大な費用がかかる。また、共通タイトル鍵の更新は、夜間に行うなどにより、鍵配信サーバの負荷を軽減することができる。また、鍵配信サーバを二重化することにより、鍵配信サーバの負荷を軽減することができる。
(2)実施の形態1、及び、実施の形態2では、個別化タイトル鍵を、記録処理毎もしくは配信処理毎に異なるものとしたが、所定数の記録処理毎もしくは配信処理毎に異なるものとしてもよい。また、変形例(1)と変形例(2)を組み合わせても良い。
(3)実施の形態1、及び、実施の形態2では、各種の公開鍵証明書の生成における署名生成、及び、署名検証に、RSA暗号を用いるとしたが、これに限定されない。任意のデジタル署名方式を利用することができる。また、各種の鍵やコンテンツの暗号化、及び、復号に、AES暗号を用いるとした、これに限定されない。任意の暗号方式を利用することができる。
(4)上記の各装置(鍵発行局、鍵配信サーバを含む)は、具体的には、マイクロプロセッサ、ROM、RAM、ハードディスクユニット、ディスプレイユニット、キーボード、マウスなどから構成されるコンピュータシステムである。前記RAMまたはハードディスクユニットには、コンピュータプログラムが記憶されている。前記マイクロプロセッサが、前記コンピュータプログラムにしたがって動作することにより、各装置は、その機能を達成する。ここでコンピュータプログラムは、所定の機能を達成するために、コンピュータに対する指令を示す命令コードが複数個組み合わされて構成されたものである。なお、各装置は、マイクロプロセッサ、ROM、RAM、ハードディスクユニット、ディスプレイユニット、キーボード、マウスなどの全てを含むコンピュータシステムには限らず、これらの一部から構成されているコンピュータシステムであってもよい。
(5)上記の各装置(鍵発行局、鍵配信サーバを含む)を構成する構成要素の一部または全部は、1個のシステムLSI(Large Scale Integration:大規模集積回路)から構成されているとしてもよい。システムLSIは、複数の構成部を1個のチップ上に集積して製造された超多機能LSIであり、具体的には、マイクロプロセッサ、ROM、RAMなどを含んで構成されるコンピュータシステムである。前記RAMには、コンピュータプログラムが記憶されている。前記マイクロプロセッサが、前記コンピュータプログラムにしたがって動作することにより、システムLSIは、その機能を達成する。
(6)上記の各装置(鍵発行局、鍵配信サーバを含む)を構成する構成要素の一部または全部は、各装置に脱着可能なICカードまたは単体のモジュールから構成されているとしてもよい。前記ICカードまたは前記モジュールは、マイクロプロセッサ、ROM、RAMなどから構成されるコンピュータシステムである。前記ICカードまたは前記モジュールは、上記の超多機能LSIを含むとしてもよい。マイクロプロセッサが、コンピュータプログラムにしたがって動作することにより、前記ICカードまたは前記モジュールは、その機能を達成する。このICカードまたはこのモジュールは、耐タンパ性を有するとしてもよい。
5 補足
更に、本発明は、下記のものであってもよい。
(1)鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムであって、前記鍵配信サーバは、記録媒体装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録媒体装置からメディア固有鍵をセキュアに受信するメディア固有鍵受信手段と、コンテンツを、共通コンテンツと個別化コンテンツに分割するコンテンツ分割手段と、コンテンツ毎に異なる第一のタイトル鍵及び第二のタイトル鍵を生成するタイトル鍵生成手段と、前記メディア固有鍵で、前記第一のタイトル鍵及び第二のタイトル鍵を暗号化する暗号化手段と、前記共通コンテンツを前記第一のタイトル鍵で暗号化する暗号化手段と、前記個別化コンテンツを前記第二のタイトル鍵で暗号化する暗号化手段と、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第二のタイトル鍵を、前記記録媒体装置に送信する送信手段と前記暗号化された個別化コンテンツを前記記録装置に送信する送信手段と、を備え、前記記録装置は、鍵配信サーバから、前記暗号化された個別化コンテンツを受信する受信手段と、記録媒体装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録媒体装置から、第二のタイトル鍵、及び、第三のタイトル鍵をセキュアに受信する受信手段と、前記暗号化された個別化コンテンツを前記第二のタイトル鍵を用いて復号する復号手段と、前記復号された個別化コンテンツを前記第三のタイトル鍵を用いて暗号化する暗号化手段と、前記第三のタイトル鍵を用いて暗号化された個別化コンテンツを記録媒体装置に送信する送信手段とを備え、前記暗号化された個別化コンテンツを記録媒体装置に送信する送信手段とを備え、前記記録媒体装置は、前記メディア固有鍵を格納する格納手段と、前記鍵配信サーバを認証する手段と、前記認証手段による認証が成功した場合に、鍵配信サーバにメディア固有鍵を、セキュアに送信する送信手段と、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第二のタイトル鍵を受信する受信手段と、前記メディア固有鍵を用いて、暗号化された第二のタイトル鍵を復号する復号手段と、記録処理毎に異なる第三のタイトル鍵を生成するタイトル鍵生成手段と、前記メディア固有鍵で、第三のタイトル鍵を暗号化する暗号化手段と、前記記録装置を認証する認証手段と、認証が成功した場合に、前記記録装置に第二のタイトル鍵と第三のタイトル鍵をセキュアに送信する送信手段と、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツを受信し、前記記録装置から、前記暗号化された個別化コンテンツを受信する受信手段と、受信した前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された個別化コンテンツ、及び、前記暗号化された第三のタイトル鍵をそれぞれを格納する格納手段と、を備える。
(2)鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムであって、鍵配信サーバは、記録媒体装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録媒体装置からメディア固有鍵をセキュアに受信するメディア固有鍵受信手段と、コンテンツを、共通コンテンツと個別化コンテンツに分割するコンテンツ分割手段と、コンテンツ毎に異なる第一のタイトル鍵及び、配信処理毎に異なる第三のタイトル鍵を生成するタイトル鍵生成手段と、前記メディア固有鍵で、前記第一のタイトル鍵と前記第三のタイトル鍵を暗号化する暗号化手段と、前記共通コンテンツを前記第一のタイトル鍵で暗号化する暗号化手段と、記録装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録装置に、第三のタイトル鍵と個別化コンテンツをセキュアに送信する送信手段と、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵を、前記記録媒体装置に送信する送信手段とを備え、前記記録装置は、鍵配信サーバを認証する認証手段と、前記認証手段による認証が成功した場合、鍵配信サーバから、第三のタイトル鍵、及び、個別化コンテンツをセキュアに受信する受信手段と、前記個別化コンテンツを前記第三のタイトル鍵を用いて暗号化する暗号化手段と、前記暗号化された個別化コンテンツを記録媒体装置に送信する送信手段とを備え、前記記録媒体装置は、前記メディア固有鍵を格納する格納手段と、前記鍵配信サーバを認証する手段と、前記認証が成功した場合に、鍵配信サーバにメディア固有鍵を、セキュアに送信する送信手段と、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵を、前記記録装置から、前記暗号化された個別化コンテンツをそれぞれ受信する受信手段と、受信した前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵、前記暗号化された個別化コンテンツをそれぞれを格納する格納手段と、を備える。
(3)記録媒体装置と再生装置とから構成される再生システムであって、前記記録媒体装置は、メディア固有鍵を格納する格納手段と、前記再生装置を認証する認証手段と、前記認証が成功した場合に、再生装置にメディア固有鍵を、セキュアに送信する送信手段と、前記再生装置に、暗号化された第一のタイトル鍵、暗号化された共通コンテンツ、暗号化された第三のタイトル鍵、暗号化された個別化コンテンツを送信する送信手段とを備え、前記再生装置は、前記記録媒体装置を認証する認証手段と、前記認証が成功した場合に、記録媒体装置からメディア固有鍵を、セキュアに受信する受信手段と、前記記録媒体装置から、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵、暗号化された個別化コンテンツを受信する受信手段と、前記メディア固有鍵を用いて、前記暗号化された第一のタイトル鍵、前記暗号化された第三のタイトル鍵を復号する復号手段と、復号された第一のタイトル鍵を用いて前記前記暗号化された共通コンテンツを復号する復号手段と、復号された第三のタイトル鍵を用いて前記暗号化された個別化コンテンツを復号する復号手段と、復号された共通コンテンツと復号された個別化コンテンツを結合するコンテンツ結合手段と、結合されたコンテンツを再生する再生手段とを備える。
(4)鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムで用いられる鍵配信サーバであって、記録媒体装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録媒体装置からメディア固有鍵をセキュアに受信するメディア固有鍵受信手段と、コンテンツを、共通コンテンツと個別化コンテンツに分割するコンテンツ分割手段と、コンテンツ毎に異なる第一のタイトル鍵及び第二のタイトル鍵を生成するタイトル鍵生成手段と、前記メディア固有鍵で、前記第一のタイトル鍵及び第二のタイトル鍵を暗号化する暗号化手段と、前記共通コンテンツを前記第一のタイトル鍵で暗号化する暗号化手段と、前記個別化コンテンツを前記第二のタイトル鍵で暗号化する暗号化手段と、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第二のタイトル鍵を、前記記録媒体装置に送信する送信手段と、前記暗号化された個別化コンテンツを前記記録装置に送信する送信手段と、を備える。
(5) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムで用いられる記録装置であって、鍵配信サーバから、前記暗号化された個別化コンテンツを受信する受信手段と、記録媒体装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録媒体装置から、第二のタイトル鍵、及び、第三のタイトル鍵をセキュアに受信する受信手段と、前記暗号化された個別化コンテンツを前記第二のタイトル鍵を用いて復号する復号手段と、前記復号された個別化コンテンツを前記第三のタイトル鍵を用いて暗号化する暗号化手段と、前記第三のタイトル鍵を用いて暗号化された個別化コンテンツを記録媒体装置に送信する送信手段とを備える。
(6) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムで用いられる記録媒体装置であって、前記メディア固有鍵を格納する格納手段と、前記鍵配信サーバを認証する手段と、前記認証手段による認証が成功した場合に、鍵配信サーバにメディア固有鍵を、セキュアに送信する送信手段と、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第二のタイトル鍵を受信する受信手段と、前記メディア固有鍵を用いて、暗号化された第二のタイトル鍵を復号する復号手段と、記録処理毎に異なる第三のタイトル鍵を生成するタイトル鍵生成手段と、前記メディア固有鍵で、第三のタイトル鍵を暗号化する暗号化手段と、前記記録装置を認証する認証手段と、認証が成功した場合に、前記記録装置に第二のタイトル鍵と第三のタイトル鍵をセキュアに送信する送信手段と、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツを受信し、前記記録装置から、前記暗号化された個別化コンテンツを受信する受信手段と、受信した前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された個別化コンテンツ、及び、前記暗号化された第三のタイトル鍵をそれぞれを格納する格納手段と、を備える。
(7) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムで用いられる鍵配信サーバであって、記録媒体装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録媒体装置からメディア固有鍵をセキュアに受信するメディア固有鍵受信手段と、コンテンツを、共通コンテンツと個別化コンテンツに分割するコンテンツ分割手段と、コンテンツ毎に異なる第一のタイトル鍵及び、配信処理毎に異なる第三のタイトル鍵を生成するタイトル鍵生成手段と、前記メディア固有鍵で、前記第一のタイトル鍵と前記第三のタイトル鍵を暗号化する暗号化手段と、前記共通コンテンツを前記第一のタイトル鍵で暗号化する暗号化手段と、記録装置を認証する認証手段と、前記認証手段による認証が成功した場合、記録装置に、第三のタイトル鍵と個別化コンテンツをセキュアに送信する送信手段と、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵を、前記記録媒体装置に送信する送信手段と、を備える。
(8) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムで用いられる記録装置であって、鍵配信サーバを認証する認証手段と、前記認証手段による認証が成功した場合、鍵配信サーバから、第三のタイトル鍵、及び、個別化コンテンツをセキュアに受信する受信手段と、前記個別化コンテンツを前記第三のタイトル鍵を用いて暗号化する暗号化手段と、前記暗号化された個別化コンテンツを記録媒体装置に送信する送信手段とを備える。
(9) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録システムで用いられる記録媒体装置であって、前記メディア固有鍵を格納する格納手段と、前記鍵配信サーバを認証する手段と、前記認証が成功した場合に、鍵配信サーバにメディア固有鍵を、セキュアに送信する送信手段と、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵を、前記記録装置から、前記暗号化された個別化コンテンツをそれぞれ受信する受信手段と、受信した前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵、前記暗号化された個別化コンテンツをそれぞれを格納する格納手段と、を備える。
(10) 記録媒体装置と再生装置とから構成される再生システムで用いられる記録媒体装置であって、メディア固有鍵を格納する格納手段と、前記再生装置を認証する手段と、前記認証が成功した場合に、再生装置にメディア固有鍵を、セキュアに送信する送信手段と、前記再生装置に、暗号化された第一のタイトル鍵、暗号化された共通コンテンツ、暗号化された第三のタイトル鍵、暗号化された個別化コンテンツを送信する送信手段とを備える。
(11) 記録媒体装置と再生装置とから構成される再生システムで用いられる再生装置であって、前記記録媒体装置を認証する手段と、前記認証が成功した場合に、記録媒体装置からメディア固有鍵を、セキュアに受信する受信手段と、前記記録媒体装置から、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵、暗号化された個別化コンテンツを受信する受信手段と、前記メディア固有鍵を用いて、前記暗号化された第一のタイトル鍵、前記暗号化された第三のタイトル鍵を復号する復号手段と、復号された第一のタイトル鍵を用いて前記前記暗号化された共通コンテンツを復号する復号手段と、復号された第三のタイトル鍵を用いて前記暗号化された個別化コンテンツを復号する復号手段と、復号された共通コンテンツと復号された個別化コンテンツを結合するコンテンツ結合手段と、結合されたコンテンツを再生する再生手段とを備える。
(12) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録方法であって、鍵配信サーバは、記録媒体装置を認証する認証ステップと、前記認証手段による認証が成功した場合、記録媒体装置からメディア固有鍵をセキュアに受信するメディア固有鍵受信ステップと、コンテンツを、共通コンテンツと個別化コンテンツに分割するコンテンツ分割ステップと、コンテンツ毎に異なる第一のタイトル鍵及び第二のタイトル鍵を生成するタイトル鍵生成ステップと、前記メディア固有鍵で、前記第一のタイトル鍵及び第二のタイトル鍵を暗号化する暗号化ステップと、前記共通コンテンツを前記第一のタイトル鍵で暗号化する暗号化ステップと、前記個別化コンテンツを前記第二のタイトル鍵で暗号化する暗号化ステップと、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第二のタイトル鍵を、前記記録媒体装置に送信する送信ステップと、前記暗号化された個別化コンテンツを前記記録装置に送信する送信ステップと、を備え、前記記録装置は、鍵配信サーバから、前記暗号化された個別化コンテンツを受信する受信ステップと、記録媒体装置を認証する認証ステップと、前記認証ステップによる認証が成功した場合、記録媒体装置から、第二のタイトル鍵、及び、第三のタイトル鍵をセキュアに受信する受信ステップと、前記暗号化された個別化コンテンツを前記第二のタイトル鍵を用いて復号する復号ステップと、前記復号された個別化コンテンツを前記第三のタイトル鍵を用いて暗号化する暗号化ステップと、前記第三のタイトル鍵を用いて暗号化された個別化コンテンツを記録媒体装置に送信する送信ステップとを備え、前記記録媒体装置は、前記メディア固有鍵を格納する格納ステップと、前記鍵配信サーバを認証するステップと、前記認証手段による認証が成功した場合に、鍵配信サーバにメディア固有鍵を、セキュアに送信する送信ステップと、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記
暗号化された第二のタイトル鍵を受信する受信ステップと、暗号化された第二のタイトル鍵を復号する復号ステップと、記録処理毎に異なる第三のタイトル鍵を生成するタイトル鍵生成ステップと、前記メディア固有鍵で、第三のタイトル鍵を暗号化する暗号化ステップと、前記記録装置を認証する認証ステップと、認証が成功した場合に、前記記録装置に第二のタイトル鍵と第三のタイトル鍵をセキュアに送信する送信ステップと、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツを受信し、前記記録装置から、前記暗号化された個別化コンテンツを受信する受信ステップと、受信した前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された個別化コンテンツ、及び、前記暗号化された第三のタイトル鍵をそれぞれを格納する格納ステップと、を備える。
(13) 鍵配信サーバと記録装置と記録媒体装置とから構成される記録方法であって、鍵配信サーバは、記録媒体装置を認証する認証ステップと、前記認証手段による認証が成功した場合、記録媒体装置からメディア固有鍵をセキュアに受信するメディア固有鍵受信ステップと、コンテンツを、共通コンテンツと個別化コンテンツに分割するコンテンツ分割ステップと、コンテンツ毎に異なる第一のタイトル鍵及び、配信処理毎に異なる第三のタイトル鍵を生成するタイトル鍵生成ステップと、前記メディア固有鍵で、前記第一のタイトル鍵と前記第三のタイトル鍵を暗号化する暗号化ステップと、前記共通コンテンツを前記第一のタイトル鍵で暗号化する暗号化ステップと、記録装置を認証する認証ステップと、前記認証手段による認証が成功した場合、記録装置に、第三のタイトル鍵と個別化コンテンツをセキュアに送信する送信ステップと、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵を、前記記録媒体装置に送信する送信ステップとを備え、前記記録装置は、鍵配信サーバを認証する認証ステップと、前記認証手段による認証が成功した場合、鍵配信サーバから、第三のタイトル鍵、及び、個別化コンテンツをセキュアに受信する受信ステップと、前記個別化コンテンツを前記第三のタイトル鍵を用いて暗号化する暗号化ステップと、前記暗号化された個別化コンテンツを記録媒体装置に送信する送信ステップとを備え、前記記録媒体装置は、前記メディア固有鍵を格納する格納ステップと、前記鍵配信サーバを認証するステップと、前記認証が成功した場合に、鍵配信サーバにメディア固有鍵を、セキュアに送信する送信ステップと、前記鍵配信サーバから、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵を、前記記録装置から、前記暗号化された個別化コンテンツをそれぞれ受信する受信ステップと、受信した前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵、前記暗号化された個別化コンテンツをそれぞれを格納する格納ステップと、を備える。
(14) 記録媒体装置と再生装置とから構成される再生方法であって、前記記録媒体装置は、メディア固有鍵を格納する格納ステップと、前記再生装置を認証する認証ステップと、前記認証が成功した場合に、再生装置にメディア固有鍵を、セキュアに送信する送信ステップと、前記再生装置に、暗号化された第一のタイトル鍵、暗号化された共通コンテンツ、暗号化された第三のタイトル鍵、暗号化された個別化コンテンツを送信する送信ステップとを備え、前記再生装置は、前記記録媒体装置を認証する認証ステップと、前記認証が成功した場合に、記録媒体装置からメディア固有鍵を、セキュアに受信する受信ステップと、前記記録媒体装置から、前記暗号化された第一のタイトル鍵、前記暗号化された共通コンテンツ、前記暗号化された第三のタイトル鍵、暗号化された個別化コンテンツを受信する受信ステップと、前記メディア固有鍵を用いて、前記暗号化された第一のタイトル鍵、前記暗号化された第三のタイトル鍵を復号する復号ステップと、復号された第一のタイトル鍵を用いて前記前記暗号化された共通コンテンツを復号する復号ステップと、復号された第三のタイトル鍵を用いて前記暗号化された個別化コンテンツを復号する復号ステップと、復号された共通コンテンツと復号された個別化コンテンツを結合するコンテンツ結合ステップと、結合されたコンテンツを再生する再生ステップとを備える。
6 その他の実施形態
上述の実施の形態1及び実施の形態2は、セキュリティを十全にするために、
認証処理、暗号化処理等を多数実行する構成としている。
6.1 実施の形態3
本実施の形態は、上述の実施の形態1に対応している。
図26は、本発明の一実施形態に係る記録再生システム1001の構成を示す図である。
図30は、本実施形態の配信・記録時の動作を示すフローチャートである。
上述の構成を備えることにより、鍵配信サーバから記録装置に配信される第1暗号化コンテンツは、セキュリティレベルの高い記録媒体装置により復号された第1タイトル鍵で一旦復号され、第2タイトル鍵で暗号化される。第2タイトル鍵は、記録媒体装置により生成され、記録処理毎に異なる鍵である。よって、第1暗号化コンテンツを復号する鍵である第1タイトル鍵が、悪意あるユーザに暴露され公開されるというタイトル鍵配布攻撃がされたとしても、記録媒体装置に格納された第2暗号化コンテンツは、公開された第1タイトル鍵では復号できない。よって、コンテンツがタイトル鍵配布攻撃により、不正に利用されてしまうのを防ぐことができる。
記録再生システム1001は、記録媒体装置に記録されたコンテンツを再生する再生装置を含んでもよい。
6.2 実施の形態4
実施の形態3では、第2タイトルの生成を記録媒体装置1004のタイトル鍵生成手段1015で行っていた。これは、セキュリティレベルを考慮した場合に、第2タイトル鍵の生成はセキュアな装置で行うのが望ましいためである。すなわち、一例としてSDカード等で構成される記録媒体装置は、一例として汎用的なパーソナルコンピュータ等で構成される記録装置よりも一般的にセキュアレベルが高いためである。
(構成)
図33は、本発明の一実施形態に係る記録再生システムの構成を示す図である。
メディア固有鍵保持手段1321、タイトル鍵保持手段1322、認証手段1323、タイトル鍵生成手段1324、タイトル鍵暗号化手段1325、コンテンツ保持手段1326、及びコンテンツ暗号化手段1327を含んで構成される。
(動作)
図37は、本実施形態のコンテンツ配信システムの動作を示すフローチャートである。
(効果)
上述の構成を備えることにより、鍵配信サーバから記録装置に配信される第1暗号化コンテンツは、セキュリティレベルの高い記録媒体装置により復号された第1タイトル鍵で一旦復号され、第2タイトル鍵で暗号化される。第2タイトル鍵は、鍵配信サーバにより生成され、配信処理毎に異なる鍵である。よって、第1暗号化コンテンツを復号する鍵である第1タイトル鍵が、悪意あるユーザに暴露され公開されるというタイトル鍵配布攻撃がされたとしても、記録媒体装置に格納された第2暗号化コンテンツは、公開された第1タイトル鍵では復号できない。よって、コンテンツがタイトル鍵配布攻撃により、不正に利用されてしまうのを防ぐことができる。
本実施の形態のコンテンツ配信システムは、記録媒体装置に記録されたコンテンツを再生する再生装置を含んでもよい。再生装置は、実施の形態3で説明したものと同様のものでよい。
6.3 変形例
なお、本発明を上記の実施の形態に基づいて説明してきたが、本発明は、上記の実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。
200 記録装置
300 記録媒体装置
400 再生装置
900 鍵発行局
Claims (19)
- 鍵配信サーバにより送信される、第1のタイトル鍵を用いて暗号化された第1の暗号化コンテンツの記録制御を行う記録装置と共に用いられる記録媒体装置であって、
記憶手段と、
前記鍵配信サーバから、暗号化された第1のタイトル鍵を受信する受信手段と、
前記暗号化された第1のタイトル鍵を復号し、前記記録装置に出力する復号手段と、
コンテンツの記録の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成手段と、
前記記録装置から、前記第1の暗号化コンテンツを前記第1のタイトル鍵で復号し前記第2のタイトル鍵で暗号化して生成された第2の暗号化コンテンツを取得して前記記憶手段に記憶させる取得手段と
を備えることを特徴とする記録媒体装置。 - 前記第1のタイトル鍵の暗号化は、前記鍵配信サーバと前記記録媒体装置との間で鍵共有された、前記記録媒体装置に固有のコントローラ個別鍵を用いて行われており、
前記記憶媒体装置は、
前記コントローラ個別鍵を保持する保持手段を備えており、
前記復号手段は、前記暗号化された第1のタイトル鍵の復号を、前記コントローラ個別鍵を用いて行う
ことを特徴とする請求項1記載の記録媒体装置。 - 前記記録媒体装置は、さらに、
前記コントローラ個別鍵で前記第2のタイトル鍵を暗号化し、前記記憶手段に記憶させる暗号化手段を備え、かつ、コンテンツ再生装置と共に用いられ、
前記コンテンツ再生装置は、
前記記録媒体装置から前記コントローラ個別鍵と、前記暗号化された第2のタイトル鍵と、前記第2のタイトル鍵により暗号化されたコンテンツとを取得する取得手段と、
前記コントローラ個別鍵を用いて、前記暗号化された第2のタイトル鍵を復号するタイトル鍵復号手段と、
前記第2のタイトル鍵を用い、前記第2のタイトル鍵により暗号化されたコンテンツを復号するコンテンツ復号手段と、
前記復号されたコンテンツを再生する再生手段とを備える
ことを特徴とする請求項2記載の記録媒体装置。 - 前記記録媒体装置は、さらに、
前記記録装置と相互認証する認証手段を備え、
前記復号手段は、前記相互認証に成功した場合にのみ、前記暗号化された第1のタイトル鍵を復号する
ことを特徴とする請求項2記載の記録媒体装置。 - 前記鍵配信サーバは、前記コントローラ個別鍵が不正な鍵である場合には、前記不正なメディア鍵により暗号化された第1のタイトル鍵を送信せず、
前記受信手段が受信する前記暗号化された第1のタイトル鍵は、不正でないコントローラ個別鍵で暗号化された第1のタイトル鍵である
ことを特徴とする請求項2記載の記録媒体装置。 - 前記タイトル鍵生成手段は、前記第2のタイトル鍵として乱数を生成する
ことを特徴とする請求項1記載の記録媒体装置。 - 前記コンテンツは、前記鍵配信サーバが保持している全体コンテンツの一部分を抽出したものである
ことを特徴とする請求項1記載の記録媒体装置。 - 前記記録媒体装置は、前記記録装置の筐体内に収容されている
ことを特徴とする請求項1記載の記録媒体装置。 - 記録媒体装置に用いられる記録方法であって、
前記記録媒体装置は、鍵配信サーバにより送信される、第1のタイトル鍵を用いて暗号化された第1の暗号化コンテンツの記録制御を行う記録装置と共に用いられ、
前記記録方法は、
前記鍵配信サーバから、暗号化された第1のタイトル鍵を受信する受信ステップと、
前記暗号化された第1のタイトル鍵を復号し、前記記録装置に出力する復号ステップと、
コンテンツの記録の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成ステップと、
前記記録装置から、前記第1の暗号化コンテンツを前記第1のタイトル鍵で復号し前記第2のタイトル鍵で暗号化して生成された第2の暗号化コンテンツを取得して記録媒体装置が有する記憶手段に記憶させる取得ステップと
を含むことを特徴とする記録方法。 - 記録媒体装置に用いられる記録プログラムを記憶するコンピュータ読取可能な記録媒体であって、
前記記録媒体装置は、鍵配信サーバにより送信される、第1のタイトル鍵を用いて暗号化された第1の暗号化コンテンツの記録制御を行う記録装置と共に用いられ、
前記記録プログラムは、
前記鍵配信サーバから、暗号化された第1のタイトル鍵を受信する受信ステップと、
前記暗号化された第1のタイトル鍵を復号し、前記記録装置に出力する復号ステップと、
コンテンツの記録の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成ステップと、
前記記録装置から、前記第1の暗号化コンテンツを前記第1のタイトル鍵で復号し前記第2のタイトル鍵で暗号化して生成された第2の暗号化コンテンツを取得して前記記録媒体装置が有する記憶手段に記憶させる取得ステップと
を含むことを特徴とする記録媒体。 - 記録媒体装置に用いられる集積回路であって、
前記記録媒体装置は、鍵配信サーバにより送信される、第1のタイトル鍵を用いて暗号化された第1の暗号化コンテンツの記録制御を行う記録装置と共に用いられ、
前記集積回路は、
記憶手段と、
前記鍵配信サーバから、暗号化された第1のタイトル鍵を受信する受信手段と、
前記暗号化された第1のタイトル鍵を復号し、前記記録装置に出力する復号手段と、
コンテンツの記録の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成手段と、
前記記録装置から、前記第1の暗号化コンテンツを前記第1のタイトル鍵で復号し前記第2のタイトル鍵で暗号化して生成された第2の暗号化コンテンツを取得して前記記憶手段に記憶させる取得手段と
を備えることを特徴とする集積回路。 - 鍵配信サーバにより送信される、第1のタイトル鍵を用いて暗号化された第1の暗号化コンテンツを記録する記録装置であって、
記憶手段と、
前記鍵配信サーバから、暗号化された第1のタイトル鍵を受信する受信手段と、
前記暗号化された第1のタイトル鍵を復号する第1の復号手段と、
コンテンツの記録の度毎に異なった鍵となる第2のタイトル鍵を生成するタイトル鍵生成手段と、
前記第1の暗号化コンテンツを前記第1のタイトル鍵で復号する第2の復号手段と、
第2の復号手段により復号されたコンテンツを、前記第2のタイトル鍵で暗号化して第2の暗号化コンテンツを生成し、前記記憶手段に記憶させる暗号化手段と
を備えることを特徴とする記録装置。 - 記録媒体装置と、コンテンツを受信して前記記録媒体装置に書き込む記録装置と共に用いられる鍵配信サーバであって、
第1のタイトル鍵を保持する鍵保持手段と、
前記コンテンツを保持するコンテンツ保持手段と、
前記コンテンツを前記第1のタイトル鍵で暗号化し前記記録装置に送信するコンテンツ暗号化手段と、
前記第1のタイトル鍵を暗号化して前記記録装置に送信するタイトル鍵暗号化手段と、
コンテンツの配信の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成手段とを備えており、
前記記録装置は、第1のタイトル鍵で暗号化されたコンテンツと、前記第1のタイトル鍵と、前記第2のタイトル鍵とを取得した場合に、前記暗号化されたコンテンツを前記第1のタイトル鍵で復号し、復号された前記コンテンツを前記第2のタイトル鍵で暗号化して前記記録媒体装置に書き込む
ことを特徴とする鍵配信サーバ。 - 前記鍵配信サーバは、さらに、
前記記録媒体装置との間で鍵共有された、前記記録媒体装置に固有のコントローラ個別鍵を保持する保持手段を備え、
前記タイトル鍵暗号化手段は、前記コントローラ個別鍵が不正な鍵でない場合のみ、前記第1のタイトル鍵の暗号化として、前記コントローラ個別鍵を用い前記第1のタイトル鍵を暗号化する
ことを特徴とする請求項13記載の鍵配信サーバ。 - 前記記録媒体装置は、さらに、前記第2のタイトル鍵を前記記録装置から取得して前記コントローラ個別鍵で暗号化して保持しており、
前記鍵配信サーバは、さらに、コンテンツ再生装置と共に用いられ、
前記コンテンツ再生装置は、
前記記録媒体装置から前記コントローラ個別鍵と、前記暗号化された第2のタイトル鍵と、前記第2のタイトル鍵により暗号化されたコンテンツとを取得する取得手段と、
前記コントローラ個別鍵を用いて、前記暗号化された第2のタイトル鍵を復号するタイトル鍵復号手段と、
前記第2のタイトル鍵を用い、前記第2のタイトル鍵により暗号化されたコンテンツを復号するコンテンツ復号手段と、
前記復号されたコンテンツを再生する再生手段とを備える
ことを特徴とする請求項14記載の鍵配信サーバ。 - 前記鍵配信サーバは、さらに、
前記記録装置と相互認証する認証手段を備え、
前記タイトル鍵生成手段による前記第2のタイトル鍵の前記記録装置への出力は、前記相互認証に成功した場合にのみ許可される
ことを特徴とする請求項13記載の鍵配信サーバ。 - 前記タイトル鍵生成手段は、前記第2のタイトル鍵として乱数を生成する
ことを特徴とする請求項13記載の鍵配信サーバ。 - 鍵配信サーバに用いられる鍵配信方法であって、
前記鍵配信サーバは、記録媒体装置と、コンテンツを受信して前記記録媒体装置に書き込む記録装置と共に用いられ、
前記鍵配信方法は、
第1のタイトル鍵を保持する鍵保持ステップと、
前記コンテンツを保持するコンテンツ保持ステップと、
前記コンテンツを前記第1のタイトル鍵で暗号化し前記記録装置に送信するコンテンツ暗号化ステップと、
前記第1のタイトル鍵を暗号化して前記記録装置に送信するタイトル鍵暗号化ステップと、
コンテンツの配信の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成ステップとを備えており、
前記記録装置は、第1のタイトル鍵で暗号化されたコンテンツと、前記第1のタイトル鍵と、前記第2のタイトル鍵とを取得した場合に、前記暗号化されたコンテンツを前記第1のタイトル鍵で復号し、復号された前記コンテンツを前記第2のタイトル鍵で暗号化して前記記録媒体装置に書き込む
ことを特徴とする鍵配信方法。 - 鍵配信サーバに用いられる鍵配信プログラムを記憶するコンピュータ読取可能な記録媒体であって、
前記鍵配信サーバは、記録媒体装置と、コンテンツを受信して前記記録媒体装置に書き込む記録装置と共に用いられ、
前記鍵配信プログラムは、
第1のタイトル鍵を保持する鍵保持ステップと、
前記コンテンツを保持するコンテンツ保持ステップと、
前記コンテンツを前記第1のタイトル鍵で暗号化し前記記録装置に送信するコンテンツ暗号化ステップと、
前記第1のタイトル鍵を暗号化して前記記録装置に送信するタイトル鍵暗号化ステップと、
コンテンツの配信の度毎に異なった鍵となる第2のタイトル鍵を生成して、前記記録装置に出力するタイトル鍵生成ステップとを備えており、
前記記録装置は、第1のタイトル鍵で暗号化されたコンテンツと、前記第1のタイトル鍵と、前記第2のタイトル鍵とを取得した場合に、前記暗号化されたコンテンツを前記第1のタイトル鍵で復号し、復号された前記コンテンツを前記第2のタイトル鍵で暗号化して前記記録媒体装置に書き込む
ことを特徴とする記録媒体。
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Also Published As
Publication number | Publication date |
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EP2546775A1 (en) | 2013-01-16 |
US20110222691A1 (en) | 2011-09-15 |
CN102422301A (zh) | 2012-04-18 |
JPWO2011111370A1 (ja) | 2013-06-27 |
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