Patent ID: 7945517
Filing Date: 2011-05-17
Classification: G06F

Abstract:
1. A recording device, comprising: an interface unit for externally communicating data; a storage unit for storing therein data storage and access restriction information received through said interface unit, said access restriction information being used to control outputting said data storage from said recording device; an authentication data hold unit holding a first public encryption key determined to correspond to said recording device and encrypted in a state decryptable with an authentication key, for external output via said interface unit when said data storage and said access restriction information are received; a first key hold unit holding a first private decryption key provided to decrypt data encrypted with said first public encryption key; a first decryption unit receiving externally via said interface unit a first symmetric key encrypted with said first public encryption key, and decrypting said first symmetric key; a second key hold unit holding a second public encryption key different for each said recording device; a session key generation unit producing a second symmetric key updated whenever said data storage is communicated; a first encryption unit encrypting said second symmetric key and said second public encryption key with said first symmetric key for output externally via said interface unit; a second decryption unit receiving said data storage and access restriction information input via said interface unit, for decryption with said second symmetric key, said data storage and access restriction information being encrypted with said second symmetric key and said second public encryption key; a third key hold unit holding a second private decryption key provided to decrypt data encrypted with said second public encryption key; a third decryption unit using said second private decryption key to decrypt said data storage and access restriction information encrypted; a control unit operative, when an external instruction is issued to output said data storage recorded in said storage unit, to refer to said access restriction information in said storage unit to determine whether reproduction information for said data storage may be output, wherein said storage unit records therein said data storage in one of a state encrypted with said second public encryption key and a state decrypted by said third decryption unit, and when said control unit determines that said data storage may be output said data storage is output and thereafter as required said control unit changes said access restriction information recorded in said storage unit.