The Furious Angels

FA Discussion => Off Topic => Topic started by: Lithium on February 18, 2009, 11:56:08 pm

Title: A Crypto Puzzle
Post by: Lithium on February 18, 2009, 11:56:08 pm
I know a lot of you enjoy a puzzle and are pretty good at it. Well I'm taking this crypto course (that I am about 15 minutes away from dropping) but I have this one homework problem I can't figure out and its annoying.

It is a substitution cipher, which means, *it should* be decrypted by substituting each letter for another letter. Anyway me and broin couldn't figure it out so you'll have bragging rights if you can...

FYNJS AJYFV SPJSQ FBKSK FSBQA SNPEA SDDCV SBYVE JBFVC HJRGA XGFDD CVVSP KCBJ

Its in blocks to make it easier to read I guess, it doesn't mean spaces, spaces should be implied, just makes it harder...

And the big hint is "pillow" occurs in the plaintext. So there are 3 places pillow would fit.

And the book gives a distribution of common letters in English language but this puzzle is going to break the distribution it seems, (just from the word pillow) making it pretty useless, but I'll post it.

e .127
t .091
a .082
o .075
i .070
n .067
s .063
h .061
r .060

Then there are other tricks, like the letter N has typically an 80% chance of being followed by a vowel, and most common digram is 'th', and 'a' 'i' and 'o' tend to avoid each other. But the puzzle is too short and these stats are hard to apply.

But anyway, if someone can figure it out maybe I'll buy you an ice cream or something :)

Thanks!
Title: Re: A Crypto Puzzle
Post by: Jarimus on February 19, 2009, 12:09:20 pm
So is this a cryptogram like in a newspaper? I didn't think it was, because there are no 6-letter words, and so no pillow.
Title: Re: A Crypto Puzzle
Post by: Lithium on February 19, 2009, 01:47:52 pm
It should be exactly like the newspaper. Note my note above that spaces do not represent actually spaces. Spaces are omitted completely and must be figured out and implied.
Title: Re: A Crypto Puzzle
Post by: Anonymous on February 19, 2009, 07:36:42 pm
I DREAMED I WAS EATING A GIANT MARSHMELLOW AND WHEN I WOKE UP MY PILLOW WAS GONE
Title: Re: A Crypto Puzzle
Post by: Lithium on February 19, 2009, 10:45:28 pm
wow. dude. you are amazing!

Thank you very much! I suck at these things I spent a lot of time on it! hah!
Title: Re: A Crypto Puzzle
Post by: Anonymous on February 20, 2009, 06:59:09 pm
Holy shit. How long did it take you?
Title: Re: A Crypto Puzzle
Post by: Anonymous on February 21, 2009, 04:45:12 pm
Damn, that's skill
Title: Re: A Crypto Puzzle
Post by: Anonymous on February 21, 2009, 08:46:41 pm
That made my brain hurt just looking at it.
Title: Re: A Crypto Puzzle
Post by: Lithium on February 21, 2009, 09:05:46 pm
The rest of the homework is 5 more problems mostly on DES encryption algorithms, a little bit of RSA public key encryption algorithms but its more mathematical notation and proof than solving a word puzzle.

It's more like understanding the math behind the impossibility of factoring 100digit primes, modular exponentintion, chinese remainder theorem, congruence, euler's formulas and all this other complex stuff that goes into making modern day digital encryption.
Title: Re: A Crypto Puzzle
Post by: likwidtek on February 22, 2009, 01:16:34 pm
wow, impressive dude.
Title: Re: A Crypto Puzzle
Post by: Anonymous on February 22, 2009, 02:45:15 pm
Abstract algebra does my head in. They reckon Chinese remainder theorem was invented to count how many soldiers they had by getting them to line up in rectangles of 7 x 7.. 11 x 11…. And counting the remainder. This gave them the exact number of soldiers. Bloody stupid if u ask me. It’s not like they needed to count heads to see how much beer and pizza to order.
Title: Re: A Crypto Puzzle
Post by: Anonymous on February 25, 2009, 03:09:57 am
Oh yeah. Skill all right. That's not an easy cipher.
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