Cryptogram maker

Type a sentence and it's turned into a cryptogram: every letter swapped for a different one, the same way all through, with a blank under each for the answer. Letters given away fills in the most common letters as a start, from none for experts to five for beginners, and Shuffle again picks a new set of swaps.

Cipher switches to seven other codes, from a Caesar shift to pigpen, if you want a secret code with a key rather than a puzzle to crack. Print gives a clean sheet, with the answer key on a page of its own.

Start with the short words. A one-letter word is almost always A or I, and the commonest three-letter word in English is THE. Then look for repeated patterns: a word like XYZZY with a doubled letter, or an apostrophe followed by one letter, which is usually S or T.

Letter frequency helps once you've got a few: E, T, A and O turn up most in English text. Fill in every place a letter appears as soon as you're sure of it, and the rest of the message starts to read itself.

Longer is easier: a sentence of 60 letters or more gives the solver patterns to work with, while a short phrase can have several possible answers. Quotations and proverbs work well because a solver can recognise them half-way through. No letter in this maker ever stands for itself, so solvers can rule that out.