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.