PRIME CALCULATION DEVICE, METHOD, AND KEY ISSUING SYSTEM

摘要

There is provided a prime calculation device for calculating a prime without duplication by a simple management of the calculation of the prime. The prime calculation device contains a known prime q and unique management information in the range where the prime is used. The prime calculation device reads out the management information, generates disturbing information R depending on the management information which has been read out, and reads out the prime q. By using the prime q read out and the disturbing information R generated, the prime calculation device calculates a prime candidate N using an equation N = 2 x disturbing information R x prime q + 1. The prime candidate N calculated is judged to be a prime or not. If it is judged to be a prime, the calculated prime candidate N is outputted as a prime. Thus, the prime calculation device can calculate a prime candidate from the unique management information without duplication.