A Block Cipher Using Linear Congruences

Abstract

We have developed a block cipher by using modular arithmetic inverse and linear congruences. The cipher contains a key matrix called the outer key. It also includes another key, which contains a set of constants involved in the linear congruences. This key is called as inner key. The cryptanalysis carried out in this paper indicates that the cipher cannot be broken by any cryptanalytic attack. This cipher is extended to the case of a larger block wherein interlacing and iteration also play a vital role.