A Novel Block Cipher Based on Randomly Shuffled Key Strings

Abstract

Information security has immense importance in today’s world of digital communication. Sharing information between intended parties while keeping it secret from any outsider is a challenging task. Cryptography provides the security of information by keeping the information secret among only the communicating parties. In this paper, a new cryptographic algorithm is propounded, which is a block cipher algorithm. A positive integer, n, two $$n\times 256$$ tables of ASCII characters, and a string, Mapper, are used as shared private keys in the proposed method. Every row of the key tables and Mapper contains a random permutation of all the ASCII characters. In the beginning of encryption of a block, an Exclusive Or (XOR) operation is done between the block and a random array of integers. Then, a 3-round substitution operation is done using the key tables and Mapper. We found that the encryption and the decryption speed of the proposed algorithm is faster than the encryption–decryption speed of Advanced Encryption Standard (AES) and Data Encryption Standard (DES). The strength of the proposed cipher was analyzed in the light of some popular attacks, and we found that the system is strong enough against those attacks. We hope that if integrated with the modern cryptography protocols, this method will enhance modern digital communication security.