International Journal of Scientific & Engineering Research, Volume 4, Issue 6, June-2013 2014 ISSN 2229-5518 IJSER © 2013 http://www.ijser.org DEVELOPING DSA TECHNIQUE BASED APPLICATION USING SQUARE GRID TRANSPOSITION Praveen Kumar Patel, Anurag Tiwari, Dr. Manuj Darbari Abstract— Data encryption is the conversion of data into a form, called cipher text that cannot be easily understood by unauthorized people. De- cryption is the process of converting encrypted data back into its original form. In literature, different techniques are used for encryption and decryp- tion of text, image, audio and video. In this work text files have been used for encryption and decryption in a grid size of 32X32 by using DSA (Digi- tal Signature Algorithm) encryption algorithm. In this paper work a modified approach for encryption of text is used with popular DSA encryption algorithm. In this work, the binary data of a file is divided into equal sized blocks called grids. The bit streams of each grid are taken and grid trans- position technique is applied over it. A key of 160 bits is used by the DSA algorithm for the grid size 32X32. The key is wrapped up with public key DSA algorithm for secret key transposition so that intruder cannot identify it. For decryption, the reverse grid transposition and private key is applied in this work. The included session key is obtained by decrypting the wrapped key with receiver’s private key. The efficiency of the work with DSA algorithm is also compared with the reported work with RSA. In this paper work, a modified approach for the encryption of the text is used called the DSA (Digital Signature Algorithm) encryption algorithm. The binary data of file is divided into equal sized blocks called as grids. Index Terms— Cryptography, Encryption, Grid Transposition, Decryption, RSA, DSA. ——————————  —————————— 1 INTRODUCTION ncryption as provided in is a process of converting messages, information, or data into a form unreadable by anyone except the intended recipient [3,4]. Encrypted data must be deciphered, or decrypted, before it can be read by the recipient. The root of the word encryption… crypt—comes from the Greek word kryptos, meaning hidden or secret [2,6,7]. In its earliest form, people have been attempting to conceal certain information that they wanted to keep to their own possession by substituting parts of the information with symbols, numbers and pictures, this paper work highlights in chronology the history of Cryptography throughout centuries. For different reason, humans have been interested in protecting their messages. Threats to computer and network security[1,2] increase with each passing day and come from a growing number of sources. No computer or network is immune from attack. A recent concern is the susceptibility of the power grid and other national infrastruc- ture to a systematic, organized attack on the United States from other nations or terrorist organizations[12,13,16]. Encryption, or the ability to store and transmit infor- mation in a form that is unreadable to anyone other than intended persons, is a critical element of our defense to these attacks[10,11,16]. Indeed, man has spent thousands of years in the quest for strong encryption algorithms. II. METHODOLOGY Step 1:A square grid of required size constructed by taking binary data from source file. Step 2:Now grid transposition applied by reading data diago- nally and writing it down on row basis from left to right. Step 3:A secret key that varies with each session as combina- tion of 0’s and 1’s is generated based on the grid size, say 160 – bit for 32– sized, 384 – bit for 64 – sized etc. Step 4:A new grid generated after transposition. Step 5:The new grid is converted into ASCII sequence and written to another file called encrypted file. Step 6:Steps 1 to 5 are repeated until the total file is formed into grids and encrypted.Padding with 0’s is done in grid formation deficiency. Step 7:Key generated for each file is encrypted with the public key of sender using DSA algorithm. Step 8:The encrypted key is then divided into various blocks and appended to file. The above steps can be shown as the operational struc- ture of the technique which includes the source file and then the implementation of the technique. The operational structure of the technique is shown below: The figure below shows all the steps in sequence. Initially, Plaintext is given as input in the form of .txt file and then the file is encrypted and decrypted using E ———————————————— • Praveen Kumar Patel is currently pursuing masters degree program in Computer Science in Babu Banarasi Das University, India PH-9935766184 E-mail: Praveenpatelsiet@gmail.com • Anurag Tiwari is currently pursuing masters degree program in Computer Science in Babu Banarasi Das University, India PH-9935766184 E-mail: E-mail: anuragrktiwari@gmail.com • Dr. Manuj Darbari is currently working as Assit. Prof in department of Information technology Babu Banarasi Das University ,lucknow IJSER