Abstract: An apparatus generates first shared information that is shared by the apparatus and a recording medium by performing a first bilateral authentication. The apparatus encrypts overwrite data that is used to erase key information item recorded in the recording medium using the first shared information. Encrypted overwrite data is transferred to the recording medium. Second shared information is generated and shared by the apparatus and the recording medium by performing a second bilateral authentication between them. The apparatus receives data that is encrypted using the second shared information and that has been used by the recording medium for erasing key information. Encrypted data is decrypted using second shared information item and key information recorded in the recording medium is erased when the decrypted data is identical to overwrite data.

Abstract: At least one set of revocation information for identifying electronic appliances that should be revoked for content protection and master revocation information for identifying electronic appliances that have special permission to update the revocation information are recorded in advance into a special storage region on a storage medium. When the storage medium is loaded into an electronic appliance indicated by the master revocation information, the revocation information can be updated. However, when the storage medium is loaded into an electronic appliance indicated by the revocation information, the electronic appliance is revoked and so the protection of contents is improved.

Abstract: An apparatus generates first shared information that is shared by the apparatus and a recording medium by performing a first bilateral authentication. The apparatus encrypts overwrite data that is used to erase key information item recorded in the recording medium using the first shared information. Encrypted overwrite data is transferred to the recording medium. Second shared information is generated and shared by the apparatus and the recording medium by performing a second bilateral authentication between them. The apparatus receives data that is encrypted using the second shared information and that has been used by the recording medium for erasing key information. Encrypted data is decrypted using second shared information item and key information recorded in the recording medium is erased when the decrypted data is identical to overwrite data.

Abstract: An apparatus generates first shared information that is shared by the apparatus and a recording medium by performing a first bilateral authentication. The apparatus encrypts overwrite data that is used to erase key information item recorded in the recording medium using the first shared information. Encrypted overwrite data is transferred to the recording medium. Second shared information is generated and shared by the apparatus and the recording medium by performing a second bilateral authentication between them. The apparatus receives data that is encrypted using the second shared information and that has been used by the recording medium for erasing key information. Encrypted data is decrypted using second shared information item and key information recorded in the recording medium is erased when the decrypted data is identical to overwrite data.

Abstract: Meta data can efficiently use a buffer, allow random access, and reduce influence of a data loss when a process that combines a moving picture at a viewer and meta data at the viewer or on a network is to be executed. The meta data is formed by including one or more Vclick access units, each of which has data for specifying a lifetime, object region data that describes the spatio-temporal region in a moving image, and a display attribute/action attribute, and is a data unit that can be processed independently.

Abstract: At least one set of revocation information for identifying electronic appliances that should be revoked for content protection and master revocation information for identifying electronic appliances that have special permission to update the revocation information are recorded in advance into a special storage region on a storage medium. When the storage medium is loaded into an electronic appliance indicated by the master revocation information, the revocation information can be updated. However, when the storage medium is loaded into an electronic appliance indicated by the revocation information, the electronic appliance is revoked and so the protection of contents is improved.

Abstract: A contents managing method of regulating a number of copied contents storable on a storage medium includes giving a predetermined number of copyable contents for each content, recording the copied contents on the storage medium upon reception of an instruction for copy recording on the storage medium when there is a remainder in the number of copyable contents, decrementing the number of copyable contents by “1” every time one copied content is recorded on the storage medium at a time of recording, and incrementing the number of copyable contents by “1” every time one copied content is erased from the storage medium upon reception of an instruction to erase the copied contents from the storage medium.

Abstract: At least one set of revocation information for identifying electronic appliances that should be revoked for content protection and master revocation information for identifying electronic appliances that have special permission to update the revocation information are recorded in advance into a special storage region on a storage medium. When the storage medium is loaded into an electronic appliance indicated by the master revocation information, the revocation information can be updated. However, when the storage medium is loaded into an electronic appliance indicated by the revocation information, the electronic appliance is revoked and so the protection of contents is improved.

Abstract: A contents managing method of regulating a number of copied contents storable on a storage medium includes giving a predetermined number of copyable contents for each content, recording the copied contents on the storage medium upon reception of an instruction for copy recording on the storage medium when there is a remainder in the number of copyable contents, decrementing the number of copyable contents by “1” every time one copied content is recorded on the storage medium at a time of recording, and incrementing the number of copyable contents by “1” every time one copied content is erased from the storage medium upon reception of an instruction to erase the copied contents from the storage medium.

Abstract: If a recording medium having a medium ID is used, a secure manager manages enciphering/decoding of a content with use of the medium ID for each recording medium. If a HDD having no medium ID is used, the secure manager obtains a device ID specific to a computer system through a BIOS and manages enciphering/decoding of a content to be recorded into the HDD, with use of the device ID. The device ID is stored in a safe area in the computer system. As a result, even if a content is recorded into an open recording medium such as a hard disk drive, the content can be protected from improper use so that utility and protection of digital contents can be improved.

Abstract: A storage medium (PM) 13 includes a controller 130 and two types of storage regions, the concealed region 134 and the open region 131. The open region 131 includes an open RW 133 storing a digital content, an open ROM-W region 132a storing, as revocation information, identification information of an electronic appliance that is prohibited from accessing the digital content, and an open ROM region 132 storing, as master revocation information, identification information of an electronic appliance that is prohibited from updating the revocation information. When the storage medium is loaded into an electronic appliance that has identification information which is registered in the open ROM region 132, the controller 130 prohibits the electronic appliance from updating the revocation information.