Chapter 1 Steganographic Micro-architectures Employing FPGA Magdy Saeb Arab Academy for Science, Technology & Maritime Transport Abstract: Real-time applications of steganography require that the processing delays are to be minimized. Therefore, hardware implementation is considered indispensable for this type of applications. In this chapter, we introduce concepts of steganographic micro-architectures for real-time data hiding employing Field Programmable Gate Arrays (FPGA). We examine video watermarking using FPGA, hardware wavelet-based data hiding, and Signature Hiding for FPGA intellectual property protection. Moreover, we discuss micro-architectures used for MPEG-4. Micro-architectures for Steganalysis and subliminal steganographic channels in cognitive radio are also discussed. We provide an explanation of the complementary relation between Steganography and Cryptography. In this respect, we show that some micro- architectures can be used for both Steganography and Cryptography data security techniques. Finally, we provide clarifications and a brief description of the FPGA technology. 1.1 Introduction and overview Steganography hides the existence of a message while Cryptography hides the meaning of the message. Both techniques are complementary and both are essential requirements for data security. Real-time applications, such as audio and video-based data hiding, require that the encountered processing delays should be kept to a minimum. Hence, hardware implementation of Steganographic techniques is considered indispensable for this type of applications. Moreover, software implementation usually requires an added special purpose processor. This processor is usually a Digital Signal Processor chip. However, adding a steganographic component will consume only a relatively small implementation silicon area. In a large number of cases of consumer electronics, the cost, area, execution speed and power consumption comparisons are supporting the hardware solution. One of the most commonly used media for hardware implementation is Field Programmable Gate Arrays or what is known as FPGA Technology. In the following sections, we discuss steganographic FPGA-based micro-architectures used for real-time data hiding. These micro-architectures cover a wide area of applications such as wavelet-based hiding, steganographic context techniques, video watermarking, signature hiding for intellectual property protection and video steganography. Although steganography is distinctly separate from cryptography, we should follow the longtime advice of A. Kerckhoffs and assume that the only unknown to the opponent is a secret key. This idea protects the user from the misapprehension of applying “security by obscurity”. History has repeatedly shown that this idea is destined to fail. Hardware-based steganography and watermarking are designed keeping in mind that they will