Data security is an important requirement for almost all, if not all, information-oriented applications such as e-commerce, digital signature, secure Internet, etc. All these services use encrypted data. Cryptography is a milliner science that was the key to the secret of ancient Rome and a fundamental piece in the Second World War. Today, it is a star in the computation world. Several operating systems, data base systems or simple filling systems provide the user with cryptographic functions that allow controlled data scrambling. Modern cryptology, which is the basis of information security techniques, started in the late 1970's and developed in the 1980's. As communication networks were spreading deep into society, the need for secure communication greatly promoted cryptographic research. The need for fast but secure cryptographic systems is growing bigger. Therefore, dedicated hardware for cryptography is becoming a key issue for designers. With the spread of reconfigurable hardware such as FPGAs, hardware implementations of cryptographic algorithms became cost-effective. The focus of this book is on all aspects of cryptographic hardware and embedded systems. This includes design, implementation and security of such systems. The content of this book is divided into four main parts, each of which is organised in three chapters, with the exception of the last one.