LO AS TR RZ IC LA YF LC MW VN UC SE LA YF PY RC HA YI IC XY
Using the method with no Q, rather than combining the I and J.
This is too hard! Can you encrypt a longer message? A short message is too hard to analyze.
The title is the keyword… if that helps. Then all you need to know is how to use the playfair cypher. Just google it, or wikipedia it.
Hah, I thought this thread was going to be about http://en.wikipedia.org/wiki/FairPlay
ahh screw it my head hurts
Oh, I already did. Very interesting, by the way. I found the document by the US Army on how to crack a Playfair cipher. But yours wasn’t long enough to look for repeating patterns.
The first thing I did was try to guess the key. I found a web site that decodes Playfair. I thought I tried “Playfair cypher” as the key. But the decoder uses the I, J combining method, so I think that’s why it didn’t work.
I’ll try manually decoding your message, but can you also post another one to crack? Something longer and with a different key. Make it something about unicycling, so I have some clue as to the content (so that it’s not impossible to solve).
Well one of the strengths of the plafair cypher is that it doesn’t have the repeating patterns of a substitution cypher. It held it’s own quite well untill the advent of computer decoding.
I used the following website to encrypt the following four sentences, simply to ensure the consistancy of the method, because there are a few variations in the method. This will be the I and J substitution method.
http://www.simonsingh.net/The_Black_Chamber/playfaircipher.htm
These are four statements that all have the word unicycle or unicycling in them. The Key word is two words, 9 letters, and is a pair of a part found on all unicycles.
TK FN VN FL RI GD LO KN DI RH KS NQ VP AC PO QY
DV WS FD NA NT DY SK MB YT DG DY NG KH BR DI FV TK QN TD TK FN VN FL RI
TY GD KQ DT NV KF DK PU BH LN DU IL RI ZY
FN VLG GY RB DY MP HK VZ GY PO IE FP NG EM DV TK N UL
There are ways to analyze it. Did you find the document created by the US Army? You have to scroll down to section 7-5 to get to the Playfair stuff. I was using that document to try to reconstruct the key to your first message – and got nowhere at all! They used the fact that the content was military in nature. They found words repeated, such as battalion and stop. They also made guesses at what appeared to be military times – such as zero four zero zero. The only patterns I could find in yours were that the sequence LA YF was found twice and IC appeared twice.
Ah, that’s the one I was using too. Thanks for ensuring the accuracy of your encoded messages! I’m going to ignore your hint regarding the key. Just as the Army found a nine letter word repeated and guessed that it was battalion, I am going to look for repeated patterns and see if I can find the word unicycle. That will help me construct part of the key.
If you decoded my original message I belive you find that LA YF was the word Play, once as played, and once as a part of playfair.
Yeah, the reason I used four simple statements in this one is because anything that would have actually needed to be encrypted for millitary or other serious purposes would have been written kind of like a telegraph… fairly short and to the point without too many unnecessary words. My first encryption was rather conversational, being that the intention was to start a conversation using encryption rather than a conversation about encryption which is why I included the keyword in the title.
One of the possible flaws in the army method, besides having to know somewhat the context of the message and millitary protocol, is that they do not use any X substitutions in their methods. Most of the ones I have seen us the letter x to seperate any double letters, or at least to break up double letters that may be found together in diagraphs… this makes it less likely to find a pattern.
not that hard. since he provided the key. also since there is an odd number of letters you have to assume that the last letter in the original text was an “x”
here’s the decrypted text
ANYONE EVER PLAY AROUND WITH PLAYFAIR CYPHERS
Yeah I did provide the key, but there isn’t an odd number of letters in the encrypted text. That’s the whole point of the x, is that there is never a doubled letter or an odd number.