ACCESS CONTROL SYSTEM, TERMINAL DEVICE, DATA TRANSMITTER, DATA KEY SERVER AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To perform access control in a group unit without sharing a secret key in a group of users. SOLUTION: Data to be transmitted from a write terminal A are enciphered by a generated data key, transmitted and stored in an enciphered data restoring part B2. The data key is enciphered by the public key of a data key server D and an ACL combining it with a list of groups transmitting data is electronically signed by the data key and stored in a signed ACL storing part B1. When a read terminal C reads data, an ACL corresponding to the identifier of data inputted from an inputting part C2 is transferred to the data key server D. When the ACL is decided as proper and also when the user name corresponding to a user identifier from an inputting part C1 is included in the group list, a data key decoded by the secret key of the data key server D is supplied to the read terminal C.