AN ODD-EVEN BLOCK CIPHER BASED CRYPTOSYSTEM THROUGH MODULO ARITHMATIC TECHNIQUE (OEMAT)

Debajyoti Guha , Alok Basu

Abstract: In this paper, a new Cryptosystem based on block cipher has been proposed where the encryption is done through Odd Even Modulo Arithmetic Technique (OEMAT). The original message is considered as a stream of bits, which is then divided into a number of blocks, each containing n bits, where n is any one of 2, 4, 8, 16, 32, 64, 128, 256. The first and the penultimate blocks are then added where the modulus of addition is 2n . The result replaces the penultimate block (say (N-1th) block), first block remaining unchanged. In the next attempt the second and the ultimate blocks (say Nth block) are added and the result replaces the Nth block. This process continues until all the blocks are executed. The modulo addition has been implemented in a very simple manner where the carry out of the MSB is discarded to get the result. The technique is applied in a cascaded manner by varying the block size from 2 to 256. The whole technique has been implemented by using a modulo subtraction technique for decryption.

Keywords: MFBOMAT, FBOMAT, Symmetric block cipher, Cryptosystem

DOI: https://doi.org/10.15623/ijret.2013.0211032