An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions, often with real-time computing constraints. It is usually embedded as a part of a complete device including hardware and embedded software. Embedded systems are commonly used in today's world ranges from portable MP4 player to most common mobile phones; others are iPAD, DTH and many more. The programs and instruction written for embedded systems are called firmware and are stored in read-only memory or flash memory. In today's world the use of embedded system is common in everybody's life. Hence, the security concern in embedded systems is growing in exponential terms. Cryptography is one of the ways to provide security in these embedded systems. Symmetric-Key cryptography is widely used for this purpose due to fast encryption, low power and area. A wide range of Non-Feistel block ciphers with various analysis are proposed in this book. So, the realization of this goal can achieved through microprocessor based solution and also fast growing FPGA. Thus this book is helpful for PhD(CSE), MS / M.Tech(CSE/IT), MCA and UG students who want to do research based final year project.