| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To realize a high-security encryption processing system and an encryption processing method with improved difficulty in analysis. <P>SOLUTION: The encryption processing system is so constituted that in the Feistel type common key block encryption processing wherein an SPN type F function having a non-linear transformation section and a linear transformation section is recursively performed a plurality of rounds, the liner transformation processing of the F function corresponding to the plurality of rounds respectively is performed as a linear transformation processing to which an MDS (Maximum Distance Separable) matrix is applied, and at least in each of the consecutive even number round and consecutive odd number round, the linear transformation processing to which different MDS matrix is applied is performed. In this constitution, the minimal number of an active S box in the entire encryption functions that is one of the strength indices of the difference attacks in the common key block encryption can be enlarged. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
