Secure and Compressed Secret Writing using DES and DEFLATE algorithm S. Smyrna Grace 1 , T. Nalini 2 and A. Pravin Kumar 3 1,2 Department of Computer Science and Engineering, Bharath University, Chennai, Tamil Nadu, India 3 Department of Computer Science and Engineering, Anna University, Chennai, Tamil Nadu, India Abstract A new secret writing using DES and DEFLATE algorithm is explored by improving the previous attempts in this sense in terms of security and compression. A Matching Pursuit algorithm using redundant basis decomposition technique is used to securely hide a message. The stability and computational complexity problems are solved by introducing new selection and update rules working entirely in the integer domain. Image decomposition is randomized in several ways thus improving the stego-message undetectability, and making the hidden message undetectable by targeted steganalyzers. A refinement decomposition step is applied to the three color bands to increase the stego-message payload. Due to the ever-increasing security threats, there is a need to develop algorithms with more complexity and advanced features for a secured message transfer. A comparative study is performed between Lempel- Ziv-Welch (LZW) data compression algorithm and deflate loss- less compression algorithm which proves the efficiency of deflate algorithm in both rate of compression and its compression speed. Keywords: DEFLATE, DES, Matching Pursuit, Redundant Basis Decomposition, Steganalyzer, Compression, and Security. 1. Introduction Security is the main concern over the transfer of files or messages from one system to another system, across any network. Security is nothing but protection of information from all kinds of threats. Security aspects come into play when it is necessary to protect information from the opponent who presents a threat to the confidentiality and eavesdropping. The ultimate goal of steganography is that of hiding a message with in an innocuous signal in such a way that the very presence of the hidden message remains secret. Matching Pursuit algorithm uses redundant basis decomposition to securely hide a message within a cover color image is explored by improving previous attempts in this sense in terms of security and payload. The stability and computational complexity problems of previous works are solved by introducing new selection and update rules working entirely in the integer domain, and by fully exploiting the availability of three color bands in such a way that all the available atoms in the three color bands are used to convey the stego-message. Image decomposition is randomized in several ways thus improving the stego-message undetectability, and making the hidden message undetectable by targeted steganalyzers explicitly developed to exploit the weaknesses of the Matching Pursuit algorithm. The main purpose of this project is to produce a file that contains a hidden file of same type such that the file presence is not felt. The hidden file can be compressed and password protected if needed and can embedded with the master file. The file can be retrieved when needed by providing correct password. Security is the main criteria while sharing files over network. Hence providing security is one of the needs of this system. The other needs of this system are providing a successful embedding of media file over another media file and performing decomposition in integer domain to reduce computational complexity. The media file here represents image, audio and video files. Before getting to the essential, it would be appropriate to understand the possibilities of the proposed project. Steganography finds tremendous scope in areas, where there is a need to protect the privacy of information or securely transmit covert information. Consider the case of a spy satellite in orbit. It could be easily made to appear as a regular weather satellite and if a high capacity image Steganography system were available, the covert information the satellite gathers could easily be hidden in common place weather images [8]. IJCSI International Journal of Computer Science Issues, Vol. 9, Issue 2, No 3, March 2012 ISSN (Online): 1694-0814 www.IJCSI.org 423 Copyright (c) 2012 International Journal of Computer Science Issues. All Rights Reserved.