Modified OTP Based Vernam Cipher Algorithm using Multilevel Encryption Method

Vernam Cipher, was known to be a perfect cipher; however, the keystream digits have to be completely random. The Stream Ciphers discourse the issues by losing a degree of security using a pseudorandom number generator, and yet the encryption on its own does not suffice to implement secure message passing, for the reason that it is “malleable” in the sense that plaintext bits can be reversed by flipping the corresponding ciphertext bit. With this, the study improved the algorithm by employing a multilevel encryption method. The Strict Avalanche Effect Criterion was utilized to evaluate the performance of the proposed encryption method. The modified method achieved the average result of 71.09% SAC with AE difference of 66.92 of the modified Vernam cipher proposed last 2016 and 63.98 of the Original Vernam Cipher, respectively. With the effect, the proposed encryption method outperformed the randomness performance with the algorithms compared.