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.
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.
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’ box is 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.
This page most recently updated Thu Apr 10 22:13:00 BST 2014
Qxw is a free (GPL) crossword construction program. Answer treatments, circular and hex grids, jumbled entries, more besides. New release 20140331 for both Linux and Windows. More...
My book, ‘Practical Signal Processing’, is published by Cambridge University Press. You can order it directly from them, or via amazon.co.uk or amazon.com. Paperback edition now also available. Browse before you buy at Google Books. Wydanie polskie.
If you find this site useful or diverting, please consider a donation to NASS (a UK registered charity), to KickAS (in the US), or to a similar body in your own country.
All trademarks used are hereby acknowledged.