International Journal of Computer Applications (0975 – 8887) Volume 69– No.18, May 2013 12 A Relevant Technique of Hiding Information in an image using Shared Cryptography Boina Avinash Kumar Scholar M.Tech Department of CS&IT Institute of Technical Education & Research, S’O’A University, Bhubaneswar, Odisha. Madhusmita Das Assistant Professor Department of CS&IT Institute of Technical Education & Research, S’O’A University, Bhubaneswar, Odisha. Madhusmita Sahu Assistant Professor Department of CS&IT Institute of Technical Education & Research, S’O’A University, Bhubaneswar, Odisha. ABSTRACT Steganography is the art and science of hidden writing. The purpose of steganography is covert communication to hide the existence of a message from an intermediate attacker .This paper will discuss about pure steganographic technique, which does not require prior exchange of data like shared-keys. The proposed technique use a secure mask generation technique and the masking of original data repeatedly generate shares. These shares of secret data are embedded using an irreversible stegonographic technique in cover image called stego image, which is sent to receiver node. General Terms Stegonography, Cryptography, Network Security Keywords Shared Cryptography, Masking Stegonography, Image Stegonography, Digital Steganography. 1. INTRODUCTION The amount of digital images has increased rapidly on the internet. Image security becomes increasingly important for many applications, for example, confidential transmission, and video surveillance, military and medical applications. Steganography: literally “hidden writing”. Now a days steganography is most often associated with embedding data in some form of electronic media[7],[8]. In steganography , the secret message is embedded in to an image (or any media) called cover image, and then sent to the reciever who extracts the secret message from the cover message. After embedding the secret message, the cover image is called a stego – image. This image should not be distinguishable from the cover image, so that the attacker cannot discover any embedded message. The difference between Steganography and the more commonly used cryptography is that while cryptography scrambles and obfuscates data that can then be accessed publicly(without consequence), Steganography conceals the data altogether [10],[15]. Data from a “covert”, or source file is hidden by altering insignificant bits of information in an “covert”, or host file[1],[4]. The security of hidden data can be obtained by two ways : Secret Share generation and steganography. A combination of two techniques can be used to increase the data security. The Secret Share generation is a technique used to scramble and obfuscates the secret data to be transmitted, by masking of original data repeatedly generate shares [3]. By using steganography the secret shares are concealed in the image and assuring that the visibility of image should not be distinguishable from the cover image, so that it almost becomes impossible for the attacker to discover any embedded messages. There are many techniques for encrypting data, which vary in their security, robustness, performance and so on. Also, there are many ways for embedding a message into another media. The most popular one is embedding a message into a coloured image using LSB. In this method the data is being hidden in the least significant bit of each pixel in the cover image [9],[12]. However, there are other known methods for hiding messages. However, there are many techniques for hiding a message in a binary image. The recent interest in digital steganography is fueled by the increased amount of communication which is mediated by computers and by the numerous potential commercial applications. The hidden information could potentially be used to detect or limit the unauthorized propagation of the innocent looking / carrier data. Because of this, there have been numerous proposals for protocols to hide data in channels containing pictures, video, audio, and even typeset text. Many of these protocols are extremely clever and rely heavily on domain-specific properties of these channels. This paper presents a new scheme for embedding bits. This algorithm is used to hide secret share data in the last 4 bits of a blue pixel in 24 bit colour image that need to be modified to hide the data successfully. The proposed Algorithm emphasized on following characteristics are Design Simplicity, Enhanced Security, Resistance against all known attacks. Our goal is to propose a steganography mechanism that allows the hiding of a large quantity of data as possible in a coloured image without resulting much difference between the original image and the embedded image significantly. A combination of implementation, analysis and evaluation has to be done for hiding information in a colour image. Section 2 consists of our scheme describes about proposed security technique algorithms. Section 3 describes about implementation of our scheme with examples. Finally conclusion is drawn in section 4,5 and Section 6 describes about future scope. 2. Proposed Security Technique The proposed Security Technique of our scheme is divided into two Algorithms. The first algorithm is “Proposed Cryptographic Algorithm” and the second algorithm is “Proposed Steganographic Algorithm”.