LOGICAL DESCRIPTION OF ENCRYPTION AND DECRYPTION TECHNIQUE USING SUBSTITUTION-TRANSPOSITION WITH BASIC ARITHMETIC AND LOGIC OPERATION

In this age of universal electronics connectivity, of viruses and hackers, of electronic eavesdropping and electronic fraud, there is indeed no time at which security does not matter. The explosive growth in computer systems and their interconnections via network has increased the dependence of both organizations and individuals on the information stored and communicated using these systems. This, in turn, has led to a heightened awareness of the need to protect data and resources from disclosure, to guarantee the authenticity of data and messages, and to protect systems from network-based attacks. The disciplines of cryptography and network security have matured, leading to the development of practical, readily available applications to enforce network security. In this paper we have proposed a cipher which uses basic encryption techniques of substitution and transposition along with application of logic gates, in order to encrypt the data.