📖 Book Cipher Kit

The cipher that needs no key — only a shared book.

"Anyone who has the book can read it. Anyone who doesn't, never will."

What is it?

A book cipher encodes each character of a message as a position inside the words of a book: (line, word, character). Without the same edition of the same book, the positions are meaningless — and there is no key to steal, no algorithm to break, no trace to find. It is the cipher of lovers, prisoners, and people who trust each other with a bookstore.

Features

• 🔡 Encode messages into line.word.char position triples
• 📚 Decode them back with the same book
• 🎲 Optional seed for reproducible (or plausibly deniable) output
• 📊 stats — tells you what your book can and cannot encode
• 🧾 Positions live in a plain text file — one triple per line, easy to hide
• 📦 Zero dependencies

Install

pip install book-cipher-kit

From source:

git clone https://github.com/AnonymoDGH/book-cipher-kit
cd book-cipher-kit
pip install -e .

Quickstart

# What can your book encode?
bookcipher stats --book novel.txt
# [*] Alphabet coverage: 98%
# [+] Found:   abcdefghijklmnopqrstuvwxyz
# [-] Missing: q

# Encode
bookcipher encode --book novel.txt --message "meet at dawn" --out coords.txt

# The courier carries only this:
cat coords.txt
# 12.4.2
# 3.1.0
# 87.12.5
# ...

# Decode on the other side
bookcipher decode --book novel.txt --input coords.txt
# meet at dawn

CLI reference

How it works

Tests

pip install pytest
pytest

License

MIT — a fiction research prop. Share the book, keep the story.