A Generalized Hill Cipher Involving Different Powers of a Key, Mixing and Substitution

Abstract

In this paper we have generalized the classical Hill cipher by including certain additional features. In this the plaintext block is divided into several matrices. Here we have found several keys by finding different powers of a single key and using modular arithmetic. Then each plaintext matrix is converted into its corresponding ciphertext matrix. On arranging all these ciphertext matrices into a single matrix, we have got the ciphertext. In this analysis we have made use of mixing and substitution for strengthening the cipher. The cryptanalysis carried out in this investigation clearly indicates that the cipher is a strong one.

Keywords: Plaintext, ciphertext, encryption, generalized Hill cipher, decryption, cryptanalysis, avalanche effect.