METHOD AND DEVICE FOR DECIPHERING DATA

摘要

PROBLEM TO BE SOLVED: To decipher data or file enciphered with a public key without knowing a secret key itself and to facilitate the management of divided keys as well by dividing the secret key with a stored primary expression and deciphering the data enciphered with the public key while using divided keys. SOLUTION: A computer 101 enciphers and preserves a document or file prepared by a user. A key generating means 102 generates the key pair of cipher to be used for the users of plural user computers 101, namely, the public key and secret key of public key cipher. The generated key pair is sent to the user computer 101 and the secret key is divided and sent to divided key holding computers 103. N pieces of divided key holding computers 103 are installed, for example, and hold the divided secret keys of the user. A data deciphering device 104 extracts information concerning the desired enciphered document to be deciphered from the user computer 101 and collects partially deciphered information from K (K<N) pieces of divided key holding computers 103 and the user deciphers the enciphered document.