A More Secure Block Cipher Generation Involving Multiple Transpositions and Substitution with a large key

Abstract

In this paper, we have devoted our attention to the study of a symmetric block cipher generation by involving multilevel transpositions
and substitution with 128 bit key. For substitution we have used our previously invented “Play color substitution algorithm”, by which we can
encrypt all types of text, numbers, symbols, images and diagrams, e.t.c. To strengthen the cipher, we have performed multiple transpositions
before substitution by using a 36bit key. In this analysis the length of the key and the permutations is playing a vital role in strengthening the
cipher. Using a sub key generation algorithm, we have divided the 128bit key into three sub keys for better performance. For secure exchange of
the key between the sender and receiver we have used RSA algorithm. The cryptanalysis thoroughly indicate the strength of the cipher.

Keywords: Cryptanalysis, symmetric block cipher, avalanche effect, play color cipher, substitution, permutation, RSA algorithm