Secure-International Data Encryption Algorithm

There are many security algorithms that are used for security purpose. IDEA is one of them. The block cipher IDEA operates with 64-bit plaintext and cipher text blocks and is controlled by a 128-bit key. The fundamental innovation in the design of this algorithm is the use of operations from three different algebraic groups. The algorithm structure has been chosen such that, with the exception that different key sub-blocks are used, the encryption process is identical to the decryption process. The drawback of IDEA is that the large numbers of weak keys were found in IDEA (International Data Encryption Algorithm). Also a new attack on round 6 of IDEA has been detected. In this paper we are describe the design and implementation of secure data encryption algorithm(S-IDEA) protocol, the size of the key has been increased from 128 bits to 256 bits. This increased key size will increase the complexity of the algorithm. To increase the amount of diffusion two MA blocks (multiplicative additive block) are used in a single round of IDEA as compared to one MA block used previously in a single round, With these modifications in the proposed algorithm will increase the cryptographic strength.