Information Technology Journal1812-56381812-5646Asian Network for Scientific Information10.3923/itj.2011.1285.1294ZanganehOmid IbrahimSubariah 72011107A real-life requirement motivated this case study of secure covert communication. Steganography is a technique used to transfer hidden information in an imperceptible manner. We proposed a novel approach of substitution technique of image steganography. The proposed method is flexible on size of secret message and allows us to embed a large amount of secret messages as well as maintaining good visual quality of stego-image. Using this method, message bits are embedded into uncertain and higher LSB layers, resulting in increased imperceptible and robustness of stego-image. Results show that the proposed algorithm provides large embedding capacity without losing the imperceptibility of the stego-image. The algorithm is also robust against Chi-square attack.]]>Al-Frajat, A.K., H.A. Jalab, Z.M. Kasirun, A.A. Zaidan and B.B. Zaidan,2010Al-Jaber, A. and I. Aloqily,2003Chan, C.K. and L.M. Cheng,2004Gonzalez, R.C. and R.E. Woods,2008Hmood, A.K., H.A. Jalab, Z.M. Kasirun, B.B. Zaidan and A.A. Zaidan,2010Hmood, A.K., B.B. Zaidan, A.A. Zaidan and H.A. Jalab,2010Lee, Y.K., G. Bell, S.Y. Huang, R.Z. Wang and S.J. Shyu,2009Lee, Y.K. and L.H. Chen,1999Stanley, C.A.,2005Tseng, L.Y., Y.K. Chan, Y.A. Ho and Y.P. Chu,2008Wang, R.Z., C.F. Lin and J.C. Lin,2001Westfeld, A. and A. Pfitzmann,1999Wu, N.I. and M.S. Hwang,2007Wu, M.N., M.H. Lin and C.C. Chang,2004Wu, H.C., N.I. Wu, C.S. Tsai and M.S. Hwang, 2005Xia, Z., X. Sun, J. Qin and C. Niu,2009Zhang, X. and S. Wang,2005