The Cipher Museum
The invisible war behind every message — from ancient substitution to quantum-proof encryption.
The Enigma Machine
Type letters on your keyboard or click the on-screen keys. Drag a rotor wheel vertically to set its starting position. Switch to Decrypt, set the rotors back to where you started, type the ciphertext, and watch the plaintext fall out — Enigma's symmetry is the whole point of the demo.
A letter can never encrypt to itself — the fatal flaw that helped crack Enigma.
The Collection
Click any cipher card to copy the ciphertext example. Filter by category to explore different families of encryption.
A Brief History of Cryptography
Scroll through the milestones that shaped how we hide information — from wax tablets to quantum keys.
Reading the Letters
Type or paste text below. Bars show your letter frequencies; the translucent band is the expected English distribution. The Index of Coincidence tells you how English-shaped your text is (English ≈ 0.067, uniform random ≈ 0.038).
Below ~30 letters the IC is unreliable noise; the chart dims to flag the low sample size.
Hands-on Instruments
Shift letters with Caesar, encode with a Vigenère keyword, or watch SHA-256 avalanche on every keystroke.