CIPHER DATA RESTORATION METHOD, KEY REGISTRATION SYSTEM AND DATA RESTORATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a data restoration system capable of restoring data prepared by a user with reliability without specifying the user and without reconstituting the secret key of the user between respective devices. ;SOLUTION: A system 12 for the user divides the secret key for the number of plural key keeping devices 31-33, generates a divided secret key, receives a public key for ciphering the divided secret key by the public key intrinsic to the respective key keeping devices, supplies the divided secret key ciphered by the public key through a key registration device 20 to the key keeping devices and respectively stores it. A data restoration device 40 receives a data key ciphered by the secret key of the user, uses blind decoding, supplies a blind ciphered data key to the key keeping device, reconstitutes the data key based on an obtained decoded result and decodes the ciphered data.;COPYRIGHT: (C)1998,JPO