In this interview, we talk to Joe and James authors of the book Cryptography and Satellite Navigation. We discuss the motivation behind writing the book, the target audience, the most useful aspects of the book, the challenges of writing the book, and advice for other engineers who are considering writing a book.
Joe Rushanan has been a Principal Mathematician at the MITRE Corporation for 38 years. He has been a part of various teams focused on GPS M-code signal design security, L1C signal design, alternative security architectures for military GPS receivers and more. He received his B.S./M.S. education from The Ohio State University in 1982 and his Ph.D. from the California Institute of Technology in 1986.
James T. Gillis has been a Senior Project Leader in the Data Science and AI Department at The Aerospace Corporation for 16 years and has been with the corporation since 1983 with various positions. His work focuses on global positioning systems, navigation technology satellites, GPS hosted payload studies, space service volume studies and more. He received his B.S. from Washington University, M.S./Ph.D. from the University of California Los Angeles.
1.Could you summarize the main content of your book? What are the key topics addressed?
Our book introduces the subjects of both cryptography and satellite navigation (satnav) and shows how the former applies to the latter. We give a broad overview of cryptography and a similar view of satnav, focusing on the aspects needed to secure the navigation signals that we all use. The application of cryptography to satnav consists both of general concepts along with some current methods being considered in both GPS and Galileo and applicable to other satnav systems.
2.What is the primary purpose of your book? How do you envision it helping readers in their work or studies?
We hope to expand the community involved with securing satellite navigation. This includes the community involved in the design of navigation systems, but more importantly and more broadly, the community that consumes the signals, from user equipment designers to the users of the equipment.
In our careers, we have often had to explain how cryptography can be applied to satnav, often to satnav engineers with no background in cryptography. Similarly, we have also often had to explain satnav to experts in cyber and cryptography, where the specific needs of satnav are usually a surprise. This book is meant to aid in both those situations.
3.What sets your book apart from other works in the same field? Are there any innovative concepts, methodologies, or insights that make it stand out?
While there are many good books on cryptography and similarly for satnav, there is only a small amount of literature in conference papers and journals on the security problem for satnav. The security of satnav system has many unique aspects that set it apart from the usual considerations, such as networking. While the broad techniques are related, the specifics pose many interesting challenges. We hope that we can illuminate the similarities and motivate and explain the differences. We have been privileged to work on satnav security problems for many decades and wish to share our views.
4.Who is the intended readership for your book? Are there specific industries, professionals, or fields of study that would benefit most from this content?
We target those interested in satnav security issues. This interest implies cross over between two disciplines: security professionals and individuals in the satnav industry. Security professionals that
are becoming interested in satnav problems will need to understand the basic mechanism of satnav to understand what the objectives and limitations of satnav technologies. Individuals with a strong background in satnav, say user equipment designers and satnav system engineers need to think clearly about the security issues in the satnav signals and the applications of cryptography.
Since we were writing for two communities, which do have not a large intersection, we hope that we extended the audience to individuals that are motivated to explore the interesting intersection of these two fields. If they have a good technical foundation, we believe this should be a good introduction to the field.
5.What are the most important lessons or insights you want readers to take away from this book?
Generally, for cryptography: what are the main parts of cryptography (symmetric, hashing, public key) and how do the respective algorithms and protocols manifest in satnav. For satnav: how does satnav work, and why is cryptography even needed, let alone what makes its applications so different.
More specifically, the problem of securing weak broadcast signals used in satnav is daunting, but there are creative solutions that can be applied. In some cases, especially for the highest reliability applications, there will have to be significant adjustments in how the signals are used.
6.Does your book include any original research, case studies, or data? If so, could you highlight some of the most significant findings?
As authors we have been involved with original research in this area for many years. The book is based on our insights as practitioners. That said, there is no specific original research. The authors are active in helping to implement some of the specific methods for satnav.
7.Does your book address any new or emerging trends in the field? How does it prepare readers for future developments?
The use of cryptographic methods to secure the civil satnav signals was first publicly suggested in 2003, and did not attract very much attention initially. In the last ten years the subject has really exploded on the scene and all the major satnav systems are considering how to improve the security of their system for their users. We review the problem that confront the satnav designers and introduce the tools available to solve the problems. We review the main approaches and outline the limitations of what can be done. Thus, the reader should be able to both appreciate and know how to achieve better understand of those emerging methods.
8.What personal experiences, if any, have shaped your perspective or approach to the topics discussed in your book?
We have worked together on GPS related security issues since the late 1990’s, with one of us, (JTG) involved in GPS for more than a decade before we met. We jointly worked on the M-Code design team and JJR is the author of the Weil code used in the GPS L1C signal. JTG was embedded in the GPS program office, with positions in user equipment and then systems engineering for more than a decade. We have worked jointly on cryptographic experiments for the soon to be launched Navigation Technology Satellite We continue to be involved in the design of innovative security solutions for satnav systems.
JJR has been recognized by the Institute of Navigation, receiving the Institute of Navigation’s 2019 Capt. P.V.H. Weems award, “for sustained contributions to the design of GPS, including M-Code, the L1C signal, and the promotion of assurance concepts for all GPS users.” JTG received an Aerospace Corp. award in 2008 for work on the GPS IIF program.
We have jointly, and separately, taught short courses on the book’s topic Institute of Navigation conferences, and in our respective institutions. It was interactions with participants in these forums that inspired us to write the book.
Learn more about the book on our websites:
ARTECH HOUSE USA : Cryptography and Satellite Navigation
ARTECH HOUSE U.K.: Cryptography and Satellite Navigation
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