Implementation of Variable Least Significant Bits Stegnography using DDDB Algorithm Sahib Khan 1 , Muhammad Haroon Yousaf 2 and Jamal Akram 3 1 Department of Telecommunication Engineering, University of Engineering and Technology, Taxila Taxila, Punjab 47080, Pakistan 2 Department of Computer Engineering, University of Engineering and Technology, Taxila Taxila, Punjab 47080, Pakistan 3 Department of Electrical Engineering, Federal Urdu University, Islamabad Islamabad, 44000, Pakistan Abstract Nobody can deny the importance of secure communication. Different techniques are being utilized to achieve this task. Image Stegnography is one such method in which we hide data in an otherwise ordinary image. In this paper, a novel Stegnographic technique named as Variable Least Significant Bits Stegnography (VLSB) is proposed. To implement VLSB, we designed an algorithm named as Decreasing Distance Decreasing Bits Algorithm (DDDBA). In each test we performed, the data hiding capacity was always greater than 50 % ( a barrier considered in image Stegnography), ranging up to 69 % with signal to noise ratio varying from 10 db to 5 db respectively. The DDDBA provides self-encryption mechanism in VLSB Stegnography, making the Steganalysis more difficult. Keywords: VLSB Stenography, DDDB Algorithm, Steganalysis, Key Size, Signal to Noise Ratio, Hiding Capacity. 1. Introduction The word ‘Stegnography’ literally means covered writing. It is a technique to camouflage the required information underneath an otherwise innocuous & routine data, in inconspicuous ways. Stegnography hides the covert information within the cover medium [1] making it difficult for anyone to detect even the presence of behind the scene secret message [2]. Stegnography is increasingly becoming popular especially in Defense Sector because of its distinctive features. In World War II, the first military use of Stegnography was seen and invisible inks were used for writing messages in between the lines of normal text message [3]. Germans in World War II used microdots. In this technology, the size of secret message containing photographs was reduced by a period. FBI director J. Edgar Hoover [4] called this technology “the enemy’s master piece of espionage”. With the development of digital images, new era of Stegnographic research started with multiple applications such as copyright protection, watermarking, fingerprinting, and Stenography [5, 7, 15 and 16]. Simmons’ formulation of the Prisoners’ Problem was itself an example of information hiding [8], [9]. Generally, information-hiding techniques are divided into two main categories: techniques in transform domain (e.g. Discrete Cosine Transform (DCT) [10] & Discrete Wavelet Domain [11] [12]), and techniques in time domain or spatial domain (e.g. LSB Stegnography, 4LSB Stegnography method [6]). 4LSB Stegnography has fixed data hiding capacity of 50% i.e. we need a cover file of almost double size as that of message file. To overcome this barrier, without compromising on security, a new technique called Variable Least Significant Bits (VLSB) Stegnography is devised. More details of data embedding and watermarking methods are available in [13]. Additional readings, software, and resources used in researching Stegnography and digital watermarking are available at [14]. 2. VLSB Stegnography Besides having a fixed limit of 50% data hiding capacity, 4LSB is relatively insecure as everyone can guess the position of actual data [17]. VLSB Stegnography, on the other hand has variable amount of data hidden in every individual pixel or group of pixels of the cover image. Cover image is divided in various groups of pixels, with each group being termed as a sector. The size of the sector is variable, ranging from the size of a complete cover file to that of a single pixel. Then, a specific number of bits “Bi”, of each individual pixel of a sector, are used for data IJCSI International Journal of Computer Science Issues, Vol. 8, Issue 6, No 3, November 2011 ISSN (Online): 1694-0814 www.IJCSI.org 292