Double Encrypted Symmetric Cryptosystem Using adjacency matrix and Linear Feedback Shift Register (LFSR)

Owing to an extensive and indiscriminate usage of social communicating networks nowadays, transfer of sensitive data genuine people has become hardship and Herculean task. Message encryption is the only tool to safeguard the original information that helps to protect the data from cyber-attacks in its journey via public channel. Graph theory is one of the important techniques used in the encryption process especially in block ciphers. Abundant research has been done in the field of cryptography using several graph theory concepts. This article explains a symmetric block cipher employing the concept of an adjacency matrix in an undirected graph. Here each block is encrypted at two different stages and three rounds at each stage. The first stage of encryption is done with an adjacency matrix and second stage using simple logical XOR operation in a special pattern. In this technique the adjacency matrix is public, the sender and receiver derive new matrices for encryption/decryption from the adjacency matrix using Linear Feedback Shift Register LFSR. LFSR polynomial acts as a secret key which is the agreement between the communicating parties.