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Simple Substitution

Any letter for any letter, with no pattern at all. The strongest one-letter cipher there is, and the hardest to remember.

Rail Fence

Press Run it to start the machine.
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Result —

How it works

The story

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Take it off the screen

Print this page and you get a worksheet: how the cipher works, where it came from, and the puzzles to crack, with the machine and the menus left off.

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Read more elsewhere

Longer, harder and written for grown-ups. Worth a look when this page runs out.

Substitution ciphers