Indian Journal of Science and Technology

Abstract

In the world of internet, Cryptography places a vital role as an effective measure to maintain information security. Whenever the security of public key cryptography algorithm increases, the execution speed decreases since both are inversely proportionate. It is mandatory to improve the security without affecting the speed. The main objective of this paper focuses on speed enhancement. Generally the encryption and decryption process is done on each characters of the plain text separately. It is a time consuming process. In this paper, the plain text is being decomposed into blocks to achieve better performance. The characters are to be grouped (Block Cipher mode) into blocks. For grouping of blocks, the plain text is replaced by the binary form of ASCII code. The binary plain text is divided into blocks with fixed size. If the size of block increases, then the execution speed is also increased. The crucial factor is to fix the block size. In some instance, the process of obtaining the plain text (decryption) is affected due to inappropriate block size. To overcome this issue, precise block size is fixed by using the proposed methodology namely Message Encoding Algorithm (MsgEncA). This algorithm is implemented in Java. As a result of proposed algorithm, the appropriate block size is fixed as double of the key size and less than modulus value. The execution speed is also analyzed with different key sizes and file sizes using RSA algorithm. The speed is compared with the existing algorithm namely Short Range of Natural Numbers (SRNN). Even when applied with different key size, the MsgEncA produces better performance with same level of security. An experimental analysis and comparison proves that the execution speed of MsgEncA is better than the existing method. In the aspect of speed, the proposed algorithm can be applied in any public key algorithms.
Keywords: Block Cipher, Decryption, Encryption, Message Encoding, Public Key Cryptography