Cryptanalysis of the Viswanath-Kumar public key cryptosystem

Abstract

Viswanath and Kumar have recently published a public key cryptosystem with the application of the Hill Cipher. The Hill Cipher is a classical cipher developed by Lester S. Hill in 1929 that uses matrix multiplication as the fundamental component of its encryption and decryption. This research strives to cryptanalyse the Viswanath-Kumar Public Key Cryptosystem and find attacks which will be able to break the cryptosystem. The method used to cryptanalyse is by attacking the cipher with attacks such as the Key Only Attack, the Ciphertext-Only Attack and the Known Message Attacks. By assuming certain conditions such as the unchanging nature of the private key matrix A, once the repetition of the other private key, integer k occurs, hence the cryptosystem will be vulnerable to the Known Message Attack. Since this cryptosystem may only be breakable with knowledge of previous pairs of plaintexts and ciphertexts, only when the attacker has sufficient information can he successfully crack it. This goes to prove that the cryptosystem is fairly secure, but needs ample improvement for conventional use.