📖 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

Core

• 🔡 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

Formats & protection

• 📦 Convert positions between text / JSON / CSV / hex / base64 (convert)
• 🔒 Passphrase encryption of positions (PBKDF2 + counter-mode SHA-256 + HMAC)
• 🗝️ Book-derived one-time pad with a burn-after-use ledger (otp-*)
• 🧩 Shamir secret sharing of passphrases — k-of-n recovery (share-*)

Steganography & disguise

• 📝 Hide positions inside generated prose (sentence-length codec, stego-*)
• 🛒 Disguise positions as a shopping list, server log, invoice, or schedule (disguise-*)
• 🔤 Acrostic and null-cipher message hiding

Analysis & operations

• 🩺 doctor — diagnoses a book, a position file, or a pair
• 🕵️ attack — cryptanalysis yardsticks (chi-squared, IoC, entropy, leakage)
• 🧮 grid-* — book-derived straddling checkerboard for compact digit streams
• 🗣️ voice-* — render positions as phonetically distinct words to read aloud
• 🧠 mnemonic — render a book fingerprint as a memorable word phrase
• 🤝 verify-* — challenge/response ceremony proving you share the same edition
• 📜 audit-* — hash-chained, tamper-evident operations log
• 📬 send / receive — the whole pipeline (encode → encrypt/disguise → audit) in one envelope
• 📦 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

The suite covers every module — core encode/decode, formats, crypto, the one-time pad, Shamir sharing, steganography, disguise schemes, the checkerboard, voice/word maps, the edition-verification ceremony, the audit chain, and the end-to-end protocol — with deterministic seeds throughout.

License

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