Cryptographic processing apparatus, algorithm constructing method, processing method, and computer program applying an extended feistel structure

摘要

To realize an extended-Feistel-type common-key block-cipher process configuration for realizing a diffusion-matrix switching mechanism (DSM). In a cryptographic process configuration in which an extended Feistel structure having a number of data lines: d that is set to an integer satisfying d≧3 is applied, a plurality of multiple different matrices are selectively applied to linear transformation processes performed in F-function sections. A plurality of different matrices satisfying a condition in which a minimum number of branches for all of the data lines is equal to or more than a predetermined value are selected as the matrices, each of the minimum numbers of branches corresponding to the data lines being based on linear transformation matrices included in F-functions that are input to a corresponding data line in the extended Feistel structure.