| 摘要 |
<p>It is possible to realize a highly safe encryption processing device having an increased analysis difficulty. In a Feistel type common key block encryption which repeatedly executes an SPN type F function having a nonlinear conversion portion and a linear conversion portion by a plurality of rounds, a linear conversion processing of the F function corresponding to each round is executed by applying a matrix satisfying a comparatively gentle restriction condition. This configuration improves resistance against a difference attack and a linear attack. Moreover, since the restriction is comparatively gentle, the number of matrix candidates which be used is increased to increase the active S-box number. That is, it is possible to increase the minimum value of the active S box as one of the encryption intensity indexes and realize a highly safe encryption processing having an improved resistance against an attack.</p> |
