| 摘要 |
PURPOSE:To improve secrecy by inverting and dividing one block of input data into plural words and inverting them, performing the calculation of a key and a system code for one word and adding them to the other word, and inverting this couple and adding them to another word after similar calculation. CONSTITUTION:One block of input data of an enciphered statement is taken out, 32 bits by 32 bits, as input data and the front inversion T of them is performed; and conversion P is carried out to divide the data into y1<1> and y1<2>. Then, calculation shown by expressions is repeated whle i=1, 2, 3-7. In this case G'li1 and G'li2 are substantially equivalent to the conversion of enciphering algorithm wherein a cyclic shift is made, but the cyclic shift is made in the opposite direction during enciphering. Other calculation processes are carried out in the opposite directions to the algorithm of enciphering. Then, conversion P<-1> for putting obtained y8<1> and y8<2> to obtain 32-bit two-dimensional data is carried out and reverse conversion T<-1> is further performed to obtain a plain statement block. |
