International Journal of Computer Applications (0975 – 8887) Volume 142 – No.10, May 2016 23 An Enhanced Method for Least Significant Bit Image Steganography using Discrete Logarithmic Dispersion Strategy Sreeparna Ganguly M.Tech. Student, Dept. of CSE JIS College of Engineering Pranati Rakshit Asst. Prof., Dept. of CSE JIS College of Engineering ABSTRACT In this paper a novel method for information security using image steganography technique is proposed. This project simply hides a text message in an image file. For hiding secret information in images, there exist a large variety of steganographic techniques some are more complex than others and all of them have respective strong and weak points. Different applications have different requirements of the steganography technique used. For example, some applications may require absolute invisibility of the secret information, while others require a larger secret message to be hidden. This work intends to give an overview of image steganography, its uses and techniques. The proposed method uses the LSB (Least Significant Bit) technique to hide information in the cover image. The system enhanced the LSB technique by randomly dispersing the bits of the message in the image and thus making it harder for unauthorized people to extract the original image. Discrete logarithm calculation technique is used for determining the location of the bit into pixel to embed the message. The proposed algorithm provides a stego-key that will be used during the embedding and extracting of the message. General Terms Image Steganography Keywords Information security, Steganography, Discrete logarithmic dispersion 1. INTRODUCTION Steganography is defined as the art and science of writing hidden messages in such a way that no one else, apart from the intended recipient knows the existence of the message. The word “steganography” is basically of Greek origin which means “hidden writing”. The word is classified into two parts: “steganos” which means “secret” and “graphic” which means “writing”. However, in hiding information, the meaning of steganography is hiding text or secret messages into another media file such as image, text, sound or video. The word “steganography” is often considered similar to “cryptography” and “watermarking”. Whilst watermarking ensures message integrity and cryptography scrambles the message, steganography hides it. The primary objective of steganography is to avoid drawing attention to the transmission of hidden information. If suspicion is raised, then this objective that has been planned to achieve the security of the secret message because if the hackers noted any change in the sent message then this observer will try to know the hidden information inside the message. Fig 1: Basic Steganography Technique The basic terminologies used in the steganography systems are: the cover message, secret message, the secret key and embedding algorithm. The cover message is the carrier of the message such as image, video, audio, text or some other digital media. The secret message is the information which is needed to be hidden in the suitable digital media. 1.1 Different kinds of Steganography Almost all digital file formats can be used for steganography, but the formats that are more suitable are those with a high degree of redundancy. Redundancy can be defined as the bits of an object that provide accuracy far greater than necessary for the object‟s use and display. The redundant bits of an object are those bits that can be altered without the alteration being detected easily. The below figure shows the four main categories of file formats that can be used for steganography. Fig 2: Different types of Steganography 1.2 Image Steganography The most widely used technique today is hiding of secret messages into a digital image. This steganography technique exploits the weakness of the human visual system (HVS). HVS cannot detect the variation in luminance of color vectors at higher frequency side of the visual spectrum. A picture can be represented by a collection of color pixels. The individual pixels can be represented by their optical characteristics like 'brightness', 'chroma' etc. Each of these characteristics can be digitally expressed in terms of 1s and 0s. The proposed method comprehends the following objectives: