In this book's story, a valuable piece of art is stolen from a museum and it is up to Inspector Jun Meguro, his sister Ruka, and the investigative reporter Rio Yoneda to decipher the clues left behind by famed burglar, Ms. Cipher, in order to stop any future thefts and hopefully put a stop to the crime spree. When Ms. Cipher leaves behind a strange message, Inspector Meguro is unable to make heads or tails from the clue, but thankfully, Ruka is an expert in cryptology and plans on teaching her brother and the nosy reporter everything she can on the topic in order to help them figure out exactly what deeds Ms. Cipher is planning.
Before The Manga Guide to Cryptography even gets into any of the math behind how modern encryption/decryption works, it dives into what the overall process of sending encoded messages is like and it does so with basic ciphers like the classic Caesar Cipher, but it also quickly explains why basic substitution ciphers like this are weak. Regardless, this early foundation is just the first step that it builds on as the book quickly dives into the math behind much more complex encryption processes and how they work.
For the most part, this book does a great job of keeping the math in easy to understand chunks, with plenty of examples to show how everything works. This is even true when it starts delving into Modulo operations, something critical to current encryption processes. This knowledge, coupled with how prime numbers are used, helps to illustrate just what is happening in encryption methods like RSA and the book eventually goes on to explain how both public and private keys are generated for securing everything from emails, to securing websites.
There were a few times when the amount of information conveyed to the reader gets dense and the thinly veiled textbook gets exposed for what it is, but those parts are few and far between. Besides, I can't imagine any other way to convey those particular parts of the lesson, so the result is a few places in an otherwise enjoyable learning experience where the reader has to do a bit of sloughing in order to understand a key piece of information that will only be built upon more in future sections.
As for the manga aspect of The Manga Guide to Cryptography, the characters are cute and fun and the storyline is a bit silly, but they do their job in softening up the material being presented. A detail I really found amusing was that the book acknowledges when puns and jokes don't quite translate from their original Japanese to English. When the inspector misunderstands one of his sister's comments because the word is similar to another word in Japanese, notes are added explaining the joke in English, and while it isn't as funny as I'm sure it was in the original text, it still helps to convey the light-hearted tone of the book as a whole.
Overall, I was really impressed with The Manga Guide to Cryptography's ability to take a complex subject and break it down to something manageable and understandable. While a reader of this book might not be able to sit down and write up a program to encrypt data as securely as what is currently being used, they will definitely be able to walk through the encryption and decryption processes presented in this book as well as understand on a fairly low level exactly what is going on when messages are sent online.
