ACCESS CONTROL SYSTEM, TERMINAL DEVICE, COALITION ATTRIBUTE CERTIFICATE AUTHORITY SERVER, AND ACCESS CONTROL PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an access control system capable of reducing operational costs associated with a change in the number of domains. SOLUTION: There is provided the access control system for requesting access to an access control apparatus by using a threshold attribute certificate. The access control system includes a distributed key producing means that divides key information for producing the threshold attribute certificate into n pieces (n is a natural number of 2 or more). The system has distributed key producing means for making it possible to produce the threshold attribute certificate when k pieces of signatures have been collected that have been obtained by using each of divided k pieces (k is a natural number defined as 1