This book is a timely document of state-of-the art analytical techniques in the domain of stream cipher design and analysis with a specific cipher, named ZUC. It links new research to brief contextual literature review in the domain of complex LFSR-based stream ciphers. A snapshot of how stream ciphers are deployed in the mobile telephony architecture, one of the most well-known topics for more than five decades in the domain of computer and communication sciences, is presented in this book. The book provides an in-depth study on design and cryptanalysis of ZUC as well as relevant research results in this field with directions towards future analysis of this cipher.