SECURITY METHOD FOR INFORMATION RECORDING MEDIUM, INFORMATION PROCESSING DEVICE, PROGRAM AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To enable a plurality of information processing devices to safely share the information recording medium, without requiring complex processes.

SOLUTION: In a storage part 13 for each of PC10-is, distributed information SSK (i, 1) on each of private keys SK (i) is stored, respectively, each of encrypted messages PE (PK (i), KA) and the distributed information SSK (i, 2), in which a common key KA of a common key encryption system is encrypted, respectively, using each of public keys PK (i), is stored in USB memory 20. Each of the PC10-is restores the private key SK (i), by using the distributed information SSK (i, 1), and the distributed information SSK (i, 2), decodes the encrypted messages PE (PK (i), KA) stored in the USB memory 20 by using it, and extracts the common key KA. Each of the PC10-is generates the encrypted messages SE (kA, M (i)) for plain text M (i) by using the extracted common key KA and stores in the USB memory 20, also by using the extracted common key KA, the encrypted message SE (kA, M (i)) read from the USB memory 20 is decoded.

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