FAST BLOCK ENCRYPTION METHOD ASSURING SECURITY FOR ATTACKS BY DIFFERENTIAL CRYPTANALYSIS AND LINEAR CRYPTANALYSIS, AND SCHEDULING METHOD FOR THE SAME

摘要

PURPOSE: A fast block encryption method guaranteeing security for attacks by differential cryptanalysis and linear cryptanalysis, and a scheduling method for the same are provided to form a round function used for an encryption structure of a Feistel structure with four S(Substitution)-boxes. CONSTITUTION: Data stream to be encrypted is divided into a left and a right block. An XOR operation of the right block and a round key is performed in a sub-block unit. The first result is inputted to the first S-box, and an XOR operation result of the first and the second result is inputted to the second S-box. The XOR operation result of the first-third results is inputted to the third S-box. The XOR operation result of the first-fourth results is inputted to the fourth S-box. Each S-box outputs the result 'E1-E4'. 'E' is output by combining the 'E1' to the 'E4'. The XOR operation result of the second step is substituted with the next left block, and the XOR operation result of the 'E' and the left block is substituted with the next right block. The previous steps are repeatedly performed by using the next left/right block and an encrypted sentence is output by combining the last left/right block values.