The improved data encryption standard (DES) algorithm

The cryptosystem which is most used throughout the world for protecting information is the Data Encryption Standard (DES) which was announced by the National Bureau of Standard (NBS). The DES must be stronger than the other cryptosystems in its security. But, because the process time required for cryptanalysis has lessened, and because hardware technique has developed rapidly, the DES may be attacked by various kinds of cryptanalysis using parallel process. It may be especially vulnerable to attack by differential cryptanalysis. Therefore, the DES will require strengthening to ensure cryptographic security in the days to come. This paper proposes design of a DES-like cryptosystem called the Improved-DES. The Improved-DES is a new algorithm. We show that the Improved-DES is stronger than the DES against differential cryptanalysis for cryptographic security. We will divide one data block (96 bits) into 3 sub-blocks of 32 bits and then perform different f functions on each of the 3 sub-blocks, and then increase the S/sub 1/-S/sub 8/ of the S-boxes to S/sub 1/-S/sub 16/, satisfying the strict avalanche criterion (SAC: p/sub i, j/) and the correlation coefficient (p/sub i, j/). Finally we will increase the key length to 112 bits. The analysis will show that the unicity distance (UD) in the Improved-DES is increased more than the DES's UD.