ENCRYPTION METHOD, DECRYPTION METHOD, DEVICE, AND PROGRAM

摘要

It is possible to improve the resistance against an impossible differential attack which is one of the interpretation methods while suppressing the increase of the mounting scale of a common key block encryption. In the middle of the generalized Feistel structure which divides data into n pieces when performing data conversion, a dispersion processing procedure which performs data conversion by linear calculation is added. With this configuration, it is possible to compensate the weakness of the dispersion of the generalized Feistel structure and reduce the number of the maximum impossible differential rounds.