Stream ciphers are a widely studied and used class of encryption algorithms, of which synchronous stream ciphers appear to offer the best combination of security and efficiency. In this book, we have implemented three synchronous stream ciphers namely Trivium, Edon80 and MICKEY. Apart from the implementation, we also mentioned these techniques against several stream cipher attacks by thoroughly analyzing the mathematical properties of their building blocks. This research should motivate designers to build stream ciphers in such a way, which are easy to analyze and for which it is easy to assess the resistance against known cryptanalytic attacks. There still remain many problems such as increasing the period of the primitive, reducing the hardware configurations and suitable designs for software applications in the search for efficient and secure synchronous stream ciphers. In the past years the interest of the research community in stream ciphers has increased considerably. It can therefore be hoped that the problems can be solved in the coming years, and that unification starts to emerge in the field of stream cipher design.