Book Cipher Challenge

📖 Can you crack this centuries-old encryption method?

Challenge 22 Aug 2025 Pro Exclusive Solution Available

Revolutionary spies used this ingenious method to hide secrets in plain sight for centuries, baffling entire governments with mysterious number sequences. 🕵️ Can you decode what looks like random digits but actually unlocks hidden messages? Discover how an ordinary book becomes the key to unbreakable encryption and put your detective skills to the ultimate test! 🔍

Flags

Points

71%

Success Rate

Start Your Challenge

~1-2 min setup

Dedicated server

Private instance

Industry standard

Open the target and find the flags

Flag

+5 pts

Book Cipher Challenge

Challenge 5 points

Writeup Guidelines

Share your solution approach, methodology, and insights. Your writeup will be reviewed before being published to the community. Earn +5 bonus points when your writeup is approved!

Requirements:

No flag content: Do not reveal actual flag values or passwords in your writeup
Include lab link: Your writeup must contain a direct link to this lab for reference
Educational focus: Explain your methodology, tools used, and learning insights

Writeup URL *

Link to your blog post, GitHub repository, or any platform where you've published your writeup
Remember to include this lab's URL in your writeup: https://hackerdna.com/labs/book-cipher-challenge

Language *

Help others find writeups in their preferred language

Confirmation Required

I confirm that my writeup includes a direct link to this lab

Your writeup must reference this lab's URL: https://hackerdna.com/labs/book-cipher-challenge

I confirm that my writeup does NOT contain flag content or critical information

Do not include actual flags, passwords, or other sensitive information that would spoil the challenge