Enlargement key generation device and darkness decoding device, enlargement key generation method, and storage

摘要

PROBLEM TO BE SOLVED: To suppress the price and scale of a device and to improve the intensity of a cipher by improving the agitation of an extended key while blocking generation of a weak key. ;SOLUTION: As individual key conversion functions fk1 to fkn, conversion processing is executed by an S box 14i (replacing table) on the basis of a first key KA obtained from an inputted key and an adding part 16i calculates extended keys K1 to K16 on the basis of a value obtained by shifting the result of the conversion by this S box 14i to the left and a second key KB obtained from the inputted key in this extended key generator, ciphering/deciphering device and recording medium.;COPYRIGHT: (C)2001,JPO