CIPHER KEY DECIPHER METHOD, CIPHER KEY DECIPHER DEVICE AND CIPHER KEY DECIPHER PROGRAM

摘要

PROBLEM TO BE SOLVED: To reduce calculation amount required for decipherring public key encryption based on discrete logarithm problem with Pollard -method.;SOLUTION: A cipher key decipher device 200 comprises: a point sequence generating section 141; and a determination processing section 242. The point sequence generating section 141 performs mapping on a point, and repeatedly performs the mapping processing on the point as a result of the mapping to generate plural points. The point sequence generating section 141 determines whether or not the generated points are characteristic points having a predetermined characteristic. The determination processing section 242 stores a point, which is not determined as characteristic point in the points generated by the point sequence generating section 141 as a determination point, in a storage. The determination processing section 242 compares the points generated by the point sequence generating section 141 and the determination point stored in the storage. When the generated points and the determination point coincide with each other, the determination processing section 242 determines that no collision occurs among the characteristic points, and starts the calculation again from another initial point.;COPYRIGHT: (C)2012,JPO&INPIT