Cryptography: The Key to Digital Security, How It Works, and Why It Matters

by Keith M. Martin

A nuts-and-bolts explanation of cryptography from a leading expert in information security.

Despite its reputation as a language only of spies and hackers, cryptography plays a critical role in our everyday lives. Though often invisible, it underpins the security of our mobile phone calls, credit card payments, web searches, internet messaging, and cryptocurrencies—in short, everything we do online. Increasingly, it also runs in the background of our smart refrigerators, thermostats, electronic car keys, and even the cars themselves. As our daily devices get smarter, cyberspace—home to all the networks that connect them—grows.

Broadly defined as a set of tools for establishing security in this expanding cyberspace, cryptography enables us to protect and share our information. Understanding the basics of cryptography is the key to recognizing the significance of the security technologies we encounter every day, which will then help us respond to them.

What are the implications of connecting to an unprotected Wi-Fi network? Is it really so important to have different passwords for different accounts? Is it safe to submit sensitive personal information to a given app, or to convert money to bitcoin? In clear, concise writing, information security expert Keith Martin answers all these questions and more, revealing the many crucial ways we all depend on cryptographic technology. He demystifies its controversial applications and the nuances behind alarming headlines about data breaches at banks, credit bureaus, and online retailers. We learn, for example, how cryptography can hamper criminal investigations and obstruct national security efforts, and how increasingly frequent ransomware attacks put personal information at risk. Yet we also learn why responding to these threats by restricting the use of cryptography can itself be problematic.

Essential reading for anyone with a password, Cryptography offers a profound perspective on personal security, online and off.

Genres: Nonfiction, Computer Science, Science, Technology, Coding

316 pages, Kindle Edition

First published May 19, 2020

About the author

Prof. Keith Martin is a professor of information security at Royal Holloway, University of London. He has broad research interests, with a focus on application of cryptography and geopolitical aspects of cyber security. Keith has authored three books on cryptography and cyber security, over 100 research publications in cyber security, as well as articles in the popular and professional press. He co-designed Royal Holloway’s online postgraduate programmes in cyber security and has overseen its cyber security doctoral programme. He has also presented courses on cyber security to a wide range of audiences, including specialist industrial short courses, the general public and schools.

Reviews

[Kerry Pickens · Rating 4 out of 5]

This a good well-organized introduction to cybersecurity for inexperienced users. It is not a technical manual for people that work in information technology. I actually work in IT Security but I manage the policy side not the implementation side. The book covers basic terms and provides lots of analogies to help you understand the concepts. It could use more illustrations for people that are visual learners.

[Fred Pierre · Rating 4 out of 5]

This book is for everyone, not just security professionals. It explains the history of cryptography and how it is used today. The author uses though experiments and analogies to explain complex authentication protocols. To the companies that we do business with online, we are known only by our cryptographic key.

[Ninja Notion · Rating 4 out of 5]

This is a very accessible book that attempts to explain the history, advantages and disadvantages of cryptography, especially its implementation in all our digital devices. You don't have to have a background in computer science, PKI, and digital encryption to read it, but it might help. The book helped me understand that I was on the right track when it comes to what I need to do to ensure my security in cyberspace. It also helped me understand, there is a certain amount of risk and cost assessment that needs to be done when considering security solutions.

I enjoyed it and geekily admit that at some points, it was a page turner for me.

[Heidi · Rating 4 out of 5]

This is a quick, accessible read on the basics of how modern cryptography works. The author manages to avoid getting too technical while providing a good description of the most common implementations of cryptography. Definitely a good introduction for anyone who wants a better understanding of digital security.

[Will Lennon · Rating 3 out of 5]

A decent introduction. A bit unfocused at times, and sometimes goes out of its way to use charming anecdotes. But... yeah, if you're looking to learn more about cryptography and cybersecurity and you're a relative novice, definitely worth a read.

[Jaime K · Rating 5 out of 5]

I really enjoyed this book, even more than I expected to. Martin weaves humor in with the facts, and offers information in a relatable way. Most of his analogies have to do with food and/or everyday things to show how physical contexts of security translate to digital ones.

Throughout the book, we learn how cryptology went from being military/state to widespread, and how it has evolved. It’s an in-depth analysis that still just brushes the surface on the benefits and challenges of cryptography, the benefits and drawbacks of different algorithms, ways to ensure data integrity, and the war on cryptography–to name a few things.

In the Keys & Algorithms chapter, Martin explains that passwords aren’t cryptology (which makes sense) but a way in which to access cryptographic keys. Good cryptographic algorithms disguise the relationship between the input and output, yet most algorithms are no longer secret. There are plenty of dilemmas of cryptology, and one must determine whether or not the benefits outweigh the risks.

There are plenty of notes at the end that point the reader to either the given resource or additional resources to provide more comprehensive information.

Additional things that jumped out at me:
- Privacy =/= secrecy
- The language of “codes” is often used incorrectly
- Symmetric vs. asymmetric algorithms, how the latter came to be, and how there is hybrid encryption that involves both
- The information on primes and RSA asymmetric encryption is fascinating. No current computer can determine the prime factorization or discrete logarithmic bases of very large numbers but they sure can generate the multiplication or logarithmic coding.
- How Bitcoin uses cryptology
- How cryptology helps authentications
- Randomness and pseudorandomness in cryptology (with a resource on the argument of randomness in math and science)
- The future of cryptography, including with quantum computers (and quantum mechanics)

[Monica Willyard Moen · Rating 5 out of 5]

Cryptography is important to everyone who uses the Internet, whether we understand it or not. What I love about this book is that the author explains the basics of cryptography without requiring the reader to have an advanced computer science degree to understand it. The author does a very nice job of breaking down complex concepts, making them approachable for people who have busy lives and don’t want to spend weeks understanding things.

[Eerke Boiten · Rating 5 out of 5]

The author is a professor of Information Security at the most established research group in the area in the UK, and I am a professor of Cyber Security in the UK too. Small enough world, so we know each other, though me coming to talk for an hour to his students and him sending me a copy of this book is as closely as we've collaborated so far.

I read the book in its entirety and I think it's achieved its main target, to pass the "Dad test". It lays out many of the core issues of where cryptography solves information security problems in a very good way - to a reader with enough general intelligence and interest in the topic, without assuming any depth of understanding of computing let alone of all the nasty and beautiful underlying mathematics. This is an achievement - there is a book called "Cryptography made simple" which cheekily omits the rest of the title which is "if you're a brilliant mathematician already". (I'll buy that author a beer if he ever points out this comment to me. May even do so if he doesn't.) Not so with this one.
Debate on how security interacts with society is becoming more and more central, and this is a tool to help in that. Read this if you want to contribute meaningfully to the debate on "end to end encryption should be made accessible to law enforcement". Not that I even fully agree with Keith on that topic, but he lays it out fairly. Read this if you want to see the common sense on hyped topics like bitcoin and blockchain, or quantum computing. Read this if you think that putting Keith Dacre in charge of policing online harms is a good idea, or if you think nobody should be anonymous on the internet. All our intelligent MPs should read this - I doubt there are more than a handful among the current lot whose insight wouldn't grow massively from it. But it's for general consumption too.

[Steve · Rating 5 out of 5]

This is a great non-technical introduction to cryptography, which explains how it works and how it is used in practice in an engaging and lively way. It's explicitly and deliberately aimed at non-specialists in everyday language and analogies that the general reader can understand - you don't need a maths or computer science degree to follow it. But it is not dumbed down - it takes real skill and deep expertise to be able to write a book like this that is true to the subject, and the author has a strong pedigree as a Professor (and former Director) in the renowned Royal Holloway Information Security Group. As it happens I know the author (though I bought my own copy of the book, unprompted) and also teach in this field, and I would certainly recommend the book to anyone who wants to understand more about how cryptography impacts their life, or wants to understand more about the technology involved in ongoing public debates about online privacy.

[Groeck The Daft · Rating 3 out of 5]

This book is a great introduction to cybersecurity for the laymen, providing background on how cryptographic systems work, giving historical examples of the evolution of cryptography, and providing thoughtful analogies to real world applications. I wish there was more focus on deconstructing the structural/network side of cryptography as applied to cyberspace, but instead this book is more based on generalities. I did appreciate the discussion of the evolution of the technology, and how an intricate balance is maintained between users and attackers and how nations have responded to advances in cybersecurity. I’m a firm believer in privacy, much like Martin, and will fight for free and private communication even at the unfortunate expense of national security. Hope to read some more in depth on the matter.

[Flashfang Reviews · Rating 5 out of 5]

I personally found this book to be an excellent introduction to the at times esoteric and obtuse world of cryptography. The author did a great job with explaining basic concepts using easy to understand analogies along with a basic history of the major topics from ancient times to the present day. Would highly recommend this book as a starting point for people who are interested in this vital field in modern society.

[Quinn · Rating 4 out of 5]

I received this Kindle book from Goodreads.com in exchange for an honest review. I guess I’m more of a geek than I thought. The author explains with examples of our everyday life how we are impacted by cryptography. If you use your phone, car, computer, etc. you are touched by cryptography. Examples were given of cryptography used by Caesar, Mary Queen of Scots, Napoleon and others. There were times I was in over my head but overall a great read.

[Drew · Rating 4 out of 5]

I read this for work and was surprised at just how much I enjoyed it. Not sure it would be helpful for anyone with much background in the subject, but as someone with only the sketchiest understanding of how cryptography works, it was perfectly targeted to my level.

If you want further thoughts, hit me up on Signal.

[Virginia · Rating 4 out of 5]

⭐️⭐️⭐️⭐️
I received an advance review copy for free, and I am leaving this review voluntarily.
Cryptography provides practical insights and strategies that are easy to understand and apply in real-world situations. It's a valuable resource for anyone looking to improve their skills and approach to business challenges.

[Autumn Kearney · Rating 5 out of 5]

I was glued to this book from start to finish. My only real exposure to cryptography was the incredible movie, Sneakers. It was way ahead of its time. So, naturally, I learned a lot from reading this book. I highly recommend it to anyone interested in the subject, especially those like me who are beginners.

[Melinda M · Rating 4 out of 5]

Cryptography: The Key to Digital Security, How It Works, and Why It Matters by Keith M. Martin is an introduction for people who do not know much about cryptography. It was interesting and easy to follow.

[Flavia · Rating 4 out of 5]

Highly readable even for those not in the field. This book packs a lot of information and food for thought into a relatively short, well-flowing text.

[Jim Henderson · Rating 4 out of 5]

A very nice overview of cryptography

[Abdulrahman · Rating 5 out of 5]

This was a really lovely read.
The book contains easy to understand examples alongside the information, and is structured quite well too

[Tyler Vale · Rating 4 out of 5]

An excellent primer in modern cryptography and its applications in cybersecurity. A bit dry at times, but that is more on the subject matter than the author.