Secure Data Hiding Using Eight Queens Solutions

The 8-queens problem of placing 8 non-attacking queens on an 8x8 chessboard is used to hide message in an image. The method helps in randomizing the bit selection in a cover image for hiding purpose. Cover image is divided into blocks of 8x1 bytes and then masked with solutions of the 8-queens problem. Bits from the block are collected corresponding to the 8-queen solution to make a 7 bit string. LSB of the block is not considered. It gives a number in the range of 0 to 127. If a bit string, corresponding to the 8-queens solutions, matches with ASCII code of the first character from message, the corresponding solution number of the 8-queens problem is encrypted using RC4, and the cipher is stored in first block of the cover. This encrypted value works as key. The solution number corresponding to next character is XORED with the key and the resultant value is embedded in the LSB of next block. The algorithm has been tested with cover of different image file formats like BMP, PNG and TIFF. The algorithm provides very good capacity, imperceptibility and robustness. DOI: 10.4018/jisp.2012100103 56 International Journal of Information Security and Privacy, 6(4), 55-70, October-December 2012 Copyright © 2012, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. In this modern era, more and more communication is taking place using public digital communication networks. A message travels across many subnets, administratively controlled by independent authority, before finally reaching its destination. Encryption and steganography are used to protect the secrecy and privacy of a message by ensuring that the message is not accessed by any third party during its life period of secrecy. The purpose of Steganography is to conceal the fact that some communication is taking place. This is achieved by hiding the secret message within another seemingly innocuous message, or carrier (Kumar & Muttoo 2011; Muttoo & Kumar, 2010b). Cryptography on the other hand does so by scrambling the data so that it should not be understood to the third party (Wang, Wu, Tsai & Hwang, 2008). The important requirement for a steganographic system is its detectability by an attacker with probability not better than random guessing, given the full knowledge of the embedding algorithm and statistical properties of cover object (Amirtharajan & Balaguru, 2009; Shih, 2008; Jung, Ha & Yoo, 2008). The distortion in cover object due to data hiding is not desirable in some applications like medical images, visual artefacts etc. In steganographic system, a digital file that is used as a carrier for hidden information is called Cover object. Cover object is also called host object. A message is text or any information that needs to be protected to ensure its privacy and secrecy. Once the message is embedded into cover object, the cover object is called stego object. Whenever a key is used to hide and extract the secret message in a steganographic system, it is called stego key. Steganographic methods could be broadly categorized into two types. The first type employs the spatial domain of a host image to camouflage secret data i.e. the secret data are directly embedded into the pixels of the host image. Steganographic methods of the second type employ the transformed domain of a host image to hide secret data. Transformation functions like the discrete cosine transform (DCT) or discrete wavelet transform (DWT) are first manoeuvred to revamp the pixel values in the spatial domain to coefficients and then the secret data is embedded in the coefficients (Lin, Lin & Wang, 2009; Thanikaiselvan, Arulmozhivarman, Amirtharajan, & Rayappan, 2011). However, the most common and well known method in digital steganography is Least Significant Bit-LSB substitution where the least significant n-bits of target pixel in cover image are embedded with message bits (Gutub, Ankeer, Abu-Ghalioun, Shaheen & Alvi, 2008; Bender, Gruhl, Morimoto & Lu, 1996). To improve this, many new optimized LSB approaches have been suggested by Liao, Wen & Zhang, (2011), Yang, Weng, Wang & Sun (2008) and Yang & Weng (2006). Chan and Cheng (2004) proposed a simple LSB substitution along with optimal pixel adjustment process (OPAP). Wang et el (2008) and Wu & Tsai (2003) proposed a new adaptive least significant bit (LSB) substitution method using pixel-value differencing (PVD) that provides a high embedding capacity and imperceptible stego images. Wu & Tsai 2003() proposed method to determine how many secret bits to be embedded based on difference value between two neighbouring pixels. The capacity of secret bits to be embedded in target pixel using side match approach is proposed by Chang & Tseng (2004) and Park, Kang, Shin & Kwon (2005). In this paper, we have proposed information hiding method based on 8-queens problem (Bell & Stevans, 2009). The 8-queens problem of placing 8 non-attacking queens on an 8x8 chessboard yields 92 solutions. A pixel in an image may be of 1 bit length to 4 to 6 bytes length depending upon the image file format. Cover image is divided into blocks of 8x1 bytes which is equivalent to 8x8 binary bit planes. To represent any of the 92 solution numbers we need only 7 bits. All solutions of 8-queens problem are applied in each bit plane except the LSB plane of a block, thereby getting 92 patterns each of 7-bits in the range of 0 to127. These 92 solutions are stored in an array. A character from message is compared with solutions of the 8-queens problem. The first matching solution number from array is encrypted using RC4, and the cipher is stored in first block of the cover. 14 more pages are available in the full version of this document, which may be purchased using the "Add to Cart" button on the product's webpage: www.igi-global.com/article/secure-data-hiding-usingeight/75322?camid=4v1 This title is available in InfoSci-Journals, InfoSci-Journal Disciplines Computer Science, Security, and Information Technology, InfoSci-Select, InfoSci-Healthcare Administration, Clinical Practice, and Bioinformatics eJournal Collection, InfoSci-Knowledge Discovery, Information Management, and Storage eJournal Collection, InfoSciSurveillance, Security, and Defense eJournal Collection. Recommend this product to your librarian: www.igi-global.com/e-resources/libraryrecommendation/?id=2