Enhancing IDEA Algorithm using Circular Shift and Middle Square Method

Abstract

Data security is an important issue and cryptographic algorithms are essential parts in security. IDEA is a symmetric block cipher and the fundamental innovation in the design is the use of operations from three different algebraic groups. The interaction of different group operations contributes to the confusion required for a secure cipher. However, IDEA has weak key classes which hindered in the faultless security of the data. Some keys containing a large number of 0 bits produce weak encryption. The encryption process of the algorithm is not enough to ensure the security against brute force attack. Circular shift and middle square method are proposed to enhance the algorithmic complexity of IDEA. The proposed enhancement will cover the number of rounds, bit adjustment, shifting, during the encryption and decryption phase. Combining middle square method and circular shift improves the randomness and promotes good diffusion.