Caesar Cipher Breaking – A Concise Edition

Welcome to the official site for the English edition of Caesar Cipher Breaking – A Concise Edition, a concise and practical guide to understanding and breaking the Caesar cipher.

This 60-page guide focuses on the Caesar cipher and its natural extension, the shift cipher—designed for beginners, educators, students, and cipher enthusiasts alike. It is part of the Classical Cipher Series, aiming to make foundational ciphers accessible to international readers.

The book prioritizes clarity and practical experimentation over abstract theory. Readers are encouraged to engage directly through tools and examples.

📖 Overview

The book is authored and translated by IPUSIRON, a Japanese cryptography writer known for works such as The Complete Guide to Cryptography and How to Build a Hacking Lab.

📘 Contents Overview

This book offers a concise and hands-on introduction to the Caesar cipher, one of the most iconic classical ciphers in cryptographic history.

Each chapter emphasizes hands-on practice over rote memorization, helping readers build true intuition.

This edition is based on the Japanese book 『シーザー暗号の解読法 簡易版』, translated and adapted by the original author.

🎯 Target Readers

A perfect starting point for beginners, students, or anyone preparing for CTF competitions.

This book is ideal for:

📥 How to Get the Book

You can download all versions for free.

👉 PDF/EPUB Download via GitHub Releases

👉 Read on Amazon Kindle

📎 All files are DRM-free and suitable for personal or educational use.

👤 About the Author

IPUSIRON is a prolific Japanese technical author and educator specializing in security and cryptography.

Born in 1979 in Soma City, Fukushima, Japan, he continues to reside in his hometown.
With over 20 years of experience in technical writing, he has published more than 30 books on cryptography, hacking, and cybersecurity—both commercially and independently.

Notable titles include:

He is also an experienced translator and editorial supervisor of cryptographic literature.

Notable translation projects include:

His professional background includes:

He currently focuses on writing, lecturing, and tool development, while continuing comprehensive research across information, physical, and human security domains.

His educational philosophy emphasizes active learning—encouraging readers not just to read, but to “learn by doing.”

In recent years, he has expanded into independently published technical books, commonly known as “doujinshi” in Japan. These self-published works allow him to explore niche topics and reach a broader range of readers beyond commercial publishing.

He has also presented at security conferences, high schools, and technical book fairs such as 技術書典 (Gijutsu-Shoten).

He serves as a board member of the Cyber Risk Defender Association, a Japanese non-profit organization focused on security awareness and education.

He is also the founder of Security Akademeia, a long-running blog where he shares tutorials, cryptographic tools, and insights from the Japanese security community.

This book is the first English installment in his Classical Cipher Series, aimed at introducing foundational cryptographic methods to an international audience.

📫 Contact

📄 License

This book is licensed under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.

You are free to:

Under the following terms:

For full license terms, see: https://creativecommons.org/licenses/by-nc/4.0/

Commercial use is allowed upon request. Please contact the author at ipusiron@gmail.com for licensing inquiries.