Non-blind Data hiding for RGB images using DCT-based fusion and H.264 compression concepts Safwat Hamad 1 and Amal Khalifa 1,2 1 Department of Scientific Computing, Faculty of Computer and Information Sciences, Ain Shams University Abbassia 11566, Cairo, Egypt shamad@cis.asu.edu.eg 2 College of Computer and Information Sciences, Princess Nora Bint Abdulrahman University Riyadh, KSA ASkhalifa@pnu.edu.sa Abstract Steganography is the field of research that provides innovative solutions to the problem of secure data communication. In this paper, a non-blind data hiding technique is proposed which is based on data fusion between both the cover and the secret images. The proposed embedding process is made in the Discrete Cosine Transform (DCT) domain of the cover image. In addition, the cover image undergoes a H.264 compression as a pre- processing step for the sake of spatial redundancy reduction. Experimental results showed that the proposed method allows an image to hide another one that is as large as itself while maintaining a remarkably outstanding invisibility performance. Furthermore, a comprehensive comparison showed that the proposed method outperformed a number of similar techniques not only in imperceptibility but also with respect to the hiding capacity. Keywords: information hiding, embedding, image, Discrete Cosine Transform, non-blind, invisibility, payload. 1. Introduction Back to 440 B.C, ancient Greek used creative ways to communicate secret information especially during war times. Beside Cryptography, information hiding techniques were used to conceal the contents of a message in some other innocent cover such that it won’t raise suspicion. In 1499, Johannes Trithemius coined the term steganography as a combination two Greek words steganos (ıIJεȖανόȢ), meaning "covered, concealed, or protected", and graphei (Ȗȡαijή) meaning "writing". Since then, Steganography has been considered as an effective tool for information security. In modern times, Steganography techniques a wide range of digital media were utilized as a host (cover) to hide or embed a piece of information (message) in such a way that it is imperceptible to a human observer but can be detected/extracted easily with a computer. These covers can take the form of any digital media such as audio tracks, Videos [1], images [2], File systems [3], networks [4], 3D objects [5], and even DNA sequences [6]. In this paper, we propose a novel technique for hiding images into other images. The proposed method is based on the properties of the recent H.264 compression technique in order to embed the secret information into the coefficients of the discrete cosine transform (DCT) of a true colored cover image. Different performance aspects of the method are measured and compared against a number of existing techniques. The rest of the paper is organized as follows: the next section gives a quick literature review on information hiding in images. Section three describes the hiding/extraction model of the proposed technique. Experimental results are presented and analyzed in section IV, where a performance comparison was held between the proposed technique and other methods highlighting weaknesses and strengths of each one of them over the others. Finally, section V summarizes the findings and conclusions. 2. Related Work Information hiding techniques in digital images are really diverse. Hence, a number of categorizations were proposed to group various techniques into a number of classes based on some criteria. One categorization is based on the domain of embedding. According to this categorization, techniques are classified into spatial- domain and transform-domain methods. Embedding in the spatial domain actually involves hiding the secret information directly in the pixel illumination values of the image [7-9]. On the other hand, transform-domain techniques hide the message by modulating coefficients in some transform domain, such as the Fourier Transform (FT) [10], Discrete-Cosine Transform (DCT) [11], and Discrete Wavelet transform (DWT) [12-18].Since most of the conventional transforms are irreversible, some hiding techniques employed the integer-to-integer wavelet transform to prevent coefficients from being potentially ACSIJ Advances in Computer Science: an International Journal, Vol. 4, Issue 3, No.15 , May 2015 ISSN : 2322-5157 www.ACSIJ.org 97 Copyright (c) 2015 Advances in Computer Science: an International Journal. All Rights Reserved.