Codes · Ciphers · Cryptanalysis · History
From the Spartan scytale to the rotor machines of the Second World War, humanity has encrypted its most vital messages using an ever-more-ingenious array of methods. TownCipher brings every one of them to life — with a hands-on workbench where the ciphertext updates in real time as you type.
Twenty-five cipher systems — Caesar, Vigenère, Pigpen, Playfair, Bifid, ADFGVX, Polybius, Beaufort, Bacon's Biliteral, Trithemius, Atbash, Autokey, Scytale, Rail Fence, Columnar Transposition, Four-Square, Tap Code, Nihilist, Straddling Checkerboard, Book Cipher, One-Time Pad, Jefferson Disk, Hagelin, and a simplified Enigma rotor simulator — each paired with its history, its mechanics, and an interactive encoder and decoder.
Beyond the encoder, explore a Cases Library of famous historical cipher events — from Mary Queen of Scots' Babington Plot to the Zimmermann Telegram. Meet the Pantheon of pioneering cryptanalysts. Follow an interactive Timeline from antiquity to the machine age.
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Mary Queen of Scots conspired in encrypted letters. Thomas Phelippes broke the cipher. She lost her head.
NomenclatorGermany secretly proposed a Mexican alliance against the USA. British codebreakers intercepted and decoded it — changing the war.
ADFGVX / DiplomaticTuring, Rejewski, and the Bletchley Park team cracked the Enigma machine. It is said to have shortened the war by two years.
Enigma · LorenzA serial killer sent taunting encrypted messages to police and newspapers. Some remain partially unsolved to this day.
Homophonic SubThree encoded texts supposedly revealed the location of buried treasure. Two remain unsolved. One used the Declaration of Independence as a key.
Book CipherAn illustrated codex written in an unknown script or cipher. Despite a century of analysis, no one has definitively decoded it.
Unknown SystemA new encoded message drops every morning — same cipher, same message for every solver worldwide. Crack it, keep the streak. Miss a day, start again.
Climb the Mastery Belts by completing graded Trials in each cipher:
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