Hamming Distance Polygram Substitution Algorithm for Coding Optimization & Security

The joint approach of integrating selective encryption & coding optimization is presented in this paper. Binary bit stream of the input is divided into the plaintext chunk of 64 bits. Random Key of 128 bits is generated. Key bits are then selected randomly. These randomly selected bits are change again randomly according to plaintext bits. Hamming distance is calculated in between the plaintext & changed key bits. Based on this Hamming distance codebook is form. Index of the codeword is treated as a cipher text which is itself a compressed code. Two levels of encryption is achieved in this work which makes the algorithm more secured than other encryption algorithm. The proposed algorithm is compared for standard test image on the basis compression performance & computational complexity. The result taken shows better performance of the proposed method over other standard methods