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AssigneePanasonic Corporation
InventorsMasato Yamamichi, Natsume Matsuzaki, Toshihisa Abe, Toshihisa Nakano, Masaya Miyazaki
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Disclosed is a digital work protection system enabling a content distributor to flexibly define usage patterns of content permitted for users. The system is composed of a recording device and a playback device. The recording device acquires a digital work, range information showing a permission range within which the digital work is permitted to be used, and a subrange key for each subrange, generates an encryption key using all the acquired subrange keys, encrypts the digital work based on the encryption key to generate encryption information, and writes the encryption information and the range information to a recording medium. The playback device reads the range information and the encrypted information from the recording medium, acquires a subrange key for each subrange, generates a decryption key using all the acquired subrange keys, decrypts the encrypted information based on the decryption key to generate a digital work, and plays the digital work.
A digital work protection system for protecting digital works from unauthorized use, comprising:
A recording device for recording digital works to a recording medium in encrypted form, comprising:
A playback device for reading and playing back digital works recorded on a recording medium by a recording device, the recording device (i) acquiring a digital work and range information showing a permission range within which the digital work is permitted to be used, the permission range being composed of at least one subrange adopted out of a plurality subranges, the range information including a plurality of pieces of adoption information each corresponding to one of the subranges and showing whether a corresponding subrange is to be adopted, (ii) acquiring a subrange key for each a subrange that is shown to be adopted in the adoption information, thereby acquiring at least one subrange key, (iii) generating an encryption key using all the acquired subrange keys, (iv) encrypting the digital work based on the encryption key, thereby generating encrypted information, and (v) writing the range information and the encrypted information to the recording medium, the playback device comprising:
A computer-readable recording medium storing range information and encrypted information, the range information including a plurality of pieces of adoption information each showing whether a corresponding one of subranges is to be adopted, a digital work is permitted to be used within a permission range composed of at least one of the subranges adopted,
A recording method for use by a recording device that records digital works to a recording medium in encrypted form, comprising:
A recording program for use by a computer that that records digital works to a recording medium in encrypted form, comprising:
A playback method for use by a playback device that reads and plays back digital works recorded on a recording medium by a recording device, the recording device (i) acquiring a digital work and range information showing a permission range within which the digital work is permitted to be used, the permission range being composed of at least one subrange adopted out of a plurality subranges, the range information including a plurality of pieces of adoption information each corresponding to one of the subranges and showing whether a corresponding subrange is to be adopted, (ii) acquiring a subrange key for each a subrange that is shown to be adopted in the adoption information, thereby acquiring at least one subrange key, (iii) generating an encryption key using all the acquired subrange keys, (iv) encrypting the digital work based on the encryption key, thereby generating encrypted information, and (v) writing the range information and the encrypted information to the recording medium, the playback method comprising:
A playback program for use by a computer that reads and plays back digital works recorded on a recording medium by a recording device, the recording device (i) acquiring a digital work and range information showing a permission range within which the digital work is permitted to be used, the permission range being composed of at least one subrange adopted out of a plurality of subranges, the range information including a plurality of pieces of adoption information each corresponding to one of the subranges and showing whether a corresponding subrange is to be adopted, (ii) acquiring a subrange key for each a subrange that is shown to be adopted in the adoption information, thereby acquiring at least one subrange key, (iii) generating an encryption key using all the acquired subrange keys, (iv) encrypting the digital work based on the encryption key, thereby generating encrypted information, and (v) writing the range information and the encrypted information to the recording medium, the playback program comprising:
Dependencies are inferred from the claim text.