Enigma Notes guide: how to use it and how it works

How to use it

Pick an alphabet and set the card. Today's card comes from the date. Shuffle draws a new one.

Type your note and the coded text appears. Press Copy link and send it to your friend.

When they open the link, it reads the settings and decodes at once. They can reply on the same card.

Send the link by chat or text. Your friend does not need to set anything up to read the note.

Write the reply on the same card and send a new link. While the card stays the same, both sides decode at once.

What the settings card is

The rotor order is which three of the five rotors sit in the machine, left to right. The start position is the letter each rotor begins on.

The plugboard swaps pairs of letters, once before and once after the rotors.

All three must match to decode. The link carries all three.

You can join up to ten plug pairs. More pairs scramble more letters. A letter can sit in only one pair.

Shuffle redraws the rotors, positions and plugs together. Press it until you like the card.

How Enigma works

Each key press turns the right rotor one step, so the same letter comes out differently each time.

The signal crosses three rotors, bounces off the reflector and comes back. That is why encoding and decoding are the same move, and why no letter maps to itself.

English uses the wiring of the 1930s Enigma I with rotors I to V and reflector B. Rotors I, II, III at start AAA turn AAAAA into BDZGO.

Korean, Japanese, Spanish and Russian

Korean syllables are split into their consonants and vowels, scrambled, then joined back, so the coded text still looks like Hangul.

Japanese runs hiragana and katakana separately, and splits voiced marks off so they scramble too.

Spanish uses A to Z plus Ñ and Ü, 28 slots. Lowercase and the accented vowels á é í ó ú are folded to the base letter, so the coded text comes out in capitals.

Russian uses the 32 Cyrillic letters. Lowercase is folded to capitals and Ё to Е.

The Korean, Japanese, Spanish and Russian rotor wirings are this app's own. They are not historical, so only English follows the real machine.

Digits, symbols, emoji and other alphabets pass through unchanged.

The reader must use the same alphabet. The link carries it, so it is set for them when they open it.

Loose consonants and vowels typed on their own may merge into syllables when decoded. Full syllables read cleanest.

Why it is not secure

Polish and British codebreakers broke Enigma in World War II. The rule that no letter maps to itself gave them a way in.

This app puts the settings in the link, so anyone holding the link can decode the note.

Send real secrets with a messenger like Signal. This app is for play.

The Korean, Japanese, Spanish and Russian wirings are published in this app. Anyone who knows the rule can work out the same result and decode.

What reaches a server

Your note, the coded text and the settings are worked out on your device. They sit after the # in the link, so they never reach a server.

Our server receives only a step name, the page language, a source label and the date.

Nothing you write is stored. Close the window and the draft is gone; only the link remains.