Thread: Need help with Playfair

Hello,
Here's my problem. I have an encrypted text with Playfair, I have the plain text, I must find the keyword. Anyone knows where to find the right tool?

several years ago I did a google search for a playfair cracker. At the time, I found a downloadable .exe (which runs on my Windows XP machine, but not under Windows 7), and it came with C code for people to compile their own executables. Today, I'm finding the source code, but not the program itself. Search for any parts of this text:

Code:

/******************************************* 
 *  playn.c                                * 
 *  Automatic Playfair solver              *
 *  by J.W. Stumpel, Jan. 2000 - Oct 2002  *
 *******************************************/

Originally Posted by Prudence

Hello,
Here's my problem. I have an encrypted text with Playfair, I have the plain text, I must find the keyword. Anyone knows where to find the right tool?

This might help

Playfair Breaker

Thank you for your answer but I know nothing about
C programs. What should I do with this text?

Thank you for that link, unfortunately the program does
works with dictionaries of common names and I
think the key is the name of a person or a place.

I found playn here:
Index of /~burt/learning/Csc609.051/programs/playn

Works decently enough but you might need to run it a few times on the same text. Sometimes it will get it, usually it won't. Keep at it though and you may find something that approximates your plaintext. It is run out of the DOS shell, so I just keep it in the root -- if you just try to launch it, it will close. Make sure to get both playn and distat. Distat.log is what seems to get google to give up the goods. Playn will not give you the key from comparing a cipher to its plaintext -- rather, playn stabs at a playfair with no known key and tries to fish the plaintext out for you.

Also, I was playing with the De-crypt.co.uk program last week and it looks quite good for playing with Playfairs where you might have some plaintext guesses. I didn't spend a great deal of time at it, but it looks better than most I've seen where you have to keep stabbing at possible keys. The download site looks dangerous, so beware -- maybe turn off javascript and such before going there; but the software seems harmless enough. I've had it on my system for about a week now with no red flags. If you have the cipher and the plaintext, this is almost certainly the software you want for finding the key.

I make no claims about the safety of either piece of software, and YMMV on their success.

I tried DeCryptCo. I think it will turn more than a week before a result. Let's be patient. I'll keep you posted.

Oh! I hope you're not hill-climbing in Decrypt.co. Read through the instructions for that software -- you can add the cipher, then fill in the known plaintext, then go to a rebuild area where it will provide square pieces to reconstruct your square.

This is why I include it for finding a playfair key from known plaintext -- it provides the right toolkit for this. Hillclimbing I'd leave to playn.