Patent ID: 8140862

Claim:
A memory device receiving an encrypted read instruction and address from the exterior and outputting data corresponding thereto to the exterior, said memory device comprising: a first storage section that stores key information for decryption and stores said key information even when said memory device is out of an information processing device; a second storage section that stores to-be-read data requested from the exterior; and a decryption control unit capable of executing processing of decrypting an encrypted read instruction and address from the exterior based on said key information, and causing data corresponding to the decrypted read instruction and address to be output from said second storage section to the exterior, wherein a circuit forming said first storage section, said second storage section, and said decryption control unit includes a first circuit area having tamper resistance and a second circuit area having a relatively higher tamper resistance compared to the first circuit area, said first storage section is composed of said circuit area having relatively higher tamper resistance, wherein said second storage section includes first and second distinct storage areas within said second storage section, and said decryption control unit is operable by switching between an encryption mode that is set when an externally input encrypted read instruction and address is input and a normal mode that is set when an externally input unencrypted read instruction and address is input in response to a setting instruction, and further wherein said decryption control unit executes said processing of decrypting the externally input encrypted read instruction and address based on said key information, and causes data corresponding to the decrypted read instruction and address to be output from said first storage area of said second storage section to the exterior in said encryption mode, and executes processing causing data corresponding to the externally input unencrypted read instruction and address to be output from said second storage area of said second storage section to the exterior in said normal mode.