LZW based Image Steganography using Kekre’s Algorithm Isha Kajal 1 , Harish Rohil 2 , Abhishek Kajal 3 1 Research Scholar, Department of Computer Science & Applications, CDLU, Sirsa, Haryana 2 Assistant Professor, Department of Computer Science & Applications, CDLU, Sirsa, Haryana 3 Assistant Professor, Department of Computer Science & Engineering, GJUS&T, Hisar, Haryana Abstract - Steganography is a method in which secret message is embedded into a cover image to protect it from unauthorized access. The challenge of steganography technique is to maintain a rational balance between the quality of file and size of data that can be transferred. This paper presents a secured and robust steganography method capable of embedding high volume of information in digital cover image without incurring and perceptual distortion. This method is based compression and encryption. In this method the message to be transmitted first using Lempel-Ziv-Welch compression technique and is encrypted by using and hide compress data in image using kekre’s algorithm. The proposed method is tested with different images and text of various lengths. Keywords- Steganography, LZW Compression, LSB Embedding Technique, PSNR, MSE 1. INTRODUCTION In the world of Internet data protection and security of the information have become critical issue. The techniques available to achieve the goal of confidential information security are cryptography, encryption and steganography. Cryptography scrambles the message so that it cannot be understand while steganography hides the existence of the message by cleverly embedding the message into a cover image. Encryption and Steganography attains the same goal via different methods. The word steganography comes from the Greek word steganos which means covered or secret and the graphy means writing or drawing [2]. Steganography don’t alter the message but hides inside a cover object. Combining encryption with steganography allows secure confident information communication hiding the secret message in the least significant bits of pixels of cover image is one of the method of steganography technique using LSB technique the image quality is not deteriorate, The image quality of stego image achieved by applying the LSB technique is very closer to the original one. Fig 1. Steganography Process There have been a large embedding techniques proposed number of steganography in the literature. These techniques modified the cover image with different approaches, Image steganography technique can be divided into two groups: a) Image domain also called spatial domain b) Transform domain also called frequency domain LSB Technique The most basic and important image Steganographic Technique is Least Significant Bit [1] embedding technique. In this technique data can be hidden in the least significant bits of the cover image and the human eye would be unable to notice the hidden image in the cover file. This technique can be used for hiding images in 24-bit, 8-bit or gray scale format. In this technique, least significant bit of each pixel is replaced with secret message bit until message end. When using a 24 bit image one can store 3 bit in each pixel by changing a bit of each if the red, green and blue color components. An 800 x 600 pixel image can store 1,4400,00 bits or 180,000 bytes of embedded data. For example a 24 bit can be as follows: (10110101 01101100 10101101) (10110110 11001101 00111110) (10110101 01100011 10001110) The number 150 which binary representation is 10010110 is embedded into the least significant bits of this part of the image, the resulting grid as follows: (10110101 01101100 10101100) (10110111 11001100 00111111) (10110101 01100010 10001110) Although the number is embedded into the first 8 bytes of the grid, only the 3 underlined bits need to be changed according to the embedded message. On an average, only half of the bits in an image will need to be modified to hide a secret message using the maximum cover size. There are 256 possible intensities of each primary color, so, changing the LSB of a pixel results in small changes in the intensity of the colors. These changes cannot be perceived by the human eye, thus the message is successfully hidden. If the message is hidden even in the second to least significant as well as in least significant bit then too no difference is seen in the image. In LSB Technique, consecutive bytes of the image data from the first byte to the end of the message are used to embed the information. But this approach is very easy to detect. A more secure system can be in which the sender and receiver share a secret key that specifies only certain pixels to be changed. Even if the intruder suspects that LSB steganography has been used, there is no way of knowing Isha Kajal et al, / (IJCSIT) International Journal of Computer Science and Information Technologies, Vol. 5 (2) , 2014, 2643-2648 www.ijcsit.com 2643