KEY RECOVERY SYSTEM, KEY RECOVERY DEVICE, RECORDING MEDIUM FOR STORING KEY RECOVERY PROGRAM AND KEY RECOVERY METHOD

摘要

PROBLEM TO BE SOLVED: To attain efficient performance of a total key recovery system. ;SOLUTION: This system is equipped with verifying devices 12a and 12b, which discriminate, in accordance with an identifier RCL1 attached to a cipher data (the cipher data obtained by ciphering the common key KS with a public key KRCpub) provided by a user's terminals 10a to 10d, whether or not a user concerned has a recovery authority for a common key KS; and a key recovery device 14, which recovers the common key by decoding the cipher data with a private key KRCpri, a counterpart of the public key KRCpub, provided separately from verifying devices 12a and 12b. The verifying devices 12 and 12b provide the user concerned with the common key KS recovered by the key recovery device 14, only when it is discriminated that the user has the recovery authority.;COPYRIGHT: (C)1999,JPO