This book aims at giving an introduction to the principles and techniques
of quantum cryptography, including secret-key distillation, as well as some
more advanced topics. As quantum cryptography is now becoming a practical
reality with products available commercially, it is important to focus not
only on the theory of quantum cryptography but also on practical issues.
For instance, what kind of security does quantum cryptography offer? How
can the raw key produced by quantum cryptography be efficiently processed
to obtain a usable secret key? What can safely be done with this key? Many
challenges remain before these questions can be answered in their full generality.
Yet quantum cryptography is mature enough to make these questions
relevant and worth discussing.
The content of this book is based on my Ph.D. thesis , which initially
focused on continuous-variable quantum cryptography protocols. When I
decided to write this book, it was essential to include discrete-variable protocols
so as to make its coverage more balanced. In all cases, the continuous
and discrete-variable protocols share many aspects in common, which makes
it interesting to discuss about them both in the same manuscript.
Quantum cryptography is a multi-disciplinary subject and, in this respect,
it may interest readers with different backgrounds. Cryptography, quantum
physics and information theory are all necessary ingredients to make quantum
cryptography work. The introductory material in each of these fields
should make the book self-contained. If necessary, references are given for
Quantum cryptography (or quantum key distribution) is a state-of-the-art technique that exploits properties of quantum mechanics to guarantee the secure exchange of secret keys. This 2006 text introduces the principles and techniques of quantum cryptography, setting it in the wider context of cryptography and security, with specific focus on secret-key distillation. The book starts with an overview chapter, progressing to classical cryptography, information theory (classical and quantum), and applications of quantum cryptography. The discussion moves to secret-key distillation, privacy amplification and reconciliation techniques, concluding with the security principles of quantum cryptography. The author explains the physical implementation and security of these systems, enabling engineers to gauge the suitability of quantum cryptography for securing transmission in their particular application. With its blend of fundamental theory, implementation techniques, and details of recent protocols, this book will be of interest to graduate students, researchers, and practitioners in electrical engineering, physics, and computer science.