Patent ID: 7433470
Filing Date: 2008-10-07
Classification: H04L

Abstract:
1. A system for performing a Feistel type common key block security encrypting process, comprising: a processor; and a memory storing a program that when executed by the processor: performs, by an SPN type F function, a nonlinear conversion process and a linear conversion process in rounds; performs, by the linear conversion process of the F function corresponding to the rounds, a linear conversion process which employs a Maximum Distance Separable (MDS) matrix, and a linear conversion process which employs different MDS matrices at consecutive odd number rounds and consecutive even number rounds; performs the Feistel type common key block encrypting process for the rounds; performs, by the linear conversion process of the F function corresponding to the rounds, a linear conversion process which employs q (where 2≦q< the number of rounds) types of different MDS matrices that are repeatedly employed in even number rounds and odd number rounds; and outputs a result of the conversion.