A Cipher Design with Automatic Key Generation using the Combination of Substitution and Transposition Techniques and Basic Arithmetic and Logic Operations

Modern computing is observed to be highly dependent on communication and data transport. The security of data during communication has become a mandatory need since the introduction of e-commerce, mails, etc. Moreover a lot of data may be required to be kept secure on local devices also. The encryption of data is the basic requirement today and thus helps to maintain confidentiality of data. A number of algorithms are available for encrypting data while it is transferred from sender to receiver. 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. The algorithm makes cryptanalysis even more difficult because of the use of “Random Number Generator” function which further decides order of encryption rounds and keys to be used to encrypt the plain text. This eliminates the overhead of defining a fixed key by the user and makes algorithm secure also. It also facilitates to transfer the key to the receiver while being added with the plain text at random locations (like added at end or beginning).