Playfair Breaker

Playfair Breaker is a simple web page that helps you break Playfair codes.

The Playfair code is a simple encryption scheme frequently used in advanced crosswords. Here is an example, which includes an explanation of how the code works.

Playfair Breaker will search for Playfair keywords that take a given plaintext to a given ciphertext. Wildcards are allowed in the plaintext, and it is possible to break a code from ciphertext alone. A surprisingly short amount of ciphertext is required!

If you get stuck at any point, click on ‘Reset’: this will reset the options to their default settings.

How to use it

Simply enter the plaintext and ciphertext in the boxes provided and click on ‘Search’. If you don’t know the plaintext, leave it blank; if you know some letters of the plaintext, enter them and insert dots in the relevant positions to stand for the letters you don’t know.

Examples

For example, enter koeqlhaeospo in the ciphertext box and click on ‘Search’. See the results: the correct keyword, promise, appears as the fourth choice (using UKACD), with corresponding plaintext giantdespair.

Enter pb in the plaintext box and au in the ciphertext box to find keywords (which include doublespacing and tricephalous) that will transmute lead into gold. See the results.

Dictionaries

There is a choice of dictionaries to search; more information about them is available here. The default, UKACD, is suitable for most UK crosswords and similar puzzles. If the ‘with repeated letters disregarded’ nox unchecked, only words in the dictionaries that have no repeated letters are considered; otherwise, all words are considered with any repeated letters dropped. The ‘Multi-word’ dictionary contains some sequences of common words that have no repeated letters.

Presentation of results

Results are shown in decreasing order of the program’s evaluation of the resulting plaintext.