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First Challenge; I'm new.
Topic Started: Dec 24 2006, 10:15 AM (559 Views)
Zofc Dec 24 2006, 10:15 AM Post #1
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 Since I'm not big on posting the whole "Hey everybody I'm new" thing. I thought I would contribute a challenge with my greeting. Here it goes:
----------------------------------------------
DEEPF ZMEEU VHLPE QYQHG HSEST
QBBNI AINKL GNHME OCENE BZLBY
HJJPV BTFMC BNRDH FBYPS SQLLY
MBQXE UUHFY CPNYW VUGKF WBZKF
IIESJ ZBGZS BXFEU RXXHK RSBLC
DAEXR JLWCK BDSAX XKEGJ KXHPJ
NOKVH YFIKL GWHGX MNRWG EHBVH
WQGFP HMUYO GBVUN ZJVJP KYLFE
TVPPL NYRVY PEJYY CPGHX JRBBI
KFTGS CXUNO YTCFE ZNMHH RQMIO
HJVVX AJXPV ZGVAV WPOFJ OAOIB
PWGZH SINVJ HORPM GSUEK BSISI
GIEJC MAWXP MMTBU DMSEA WXXRV
BXMOK ICGKA SSXDO MQPTX

-----------------------------------------------





Hint: Vigenere
FZZIX IMAEG GVTHX ENFHR FTPKB LLDIA ZAAGC WHMJV FRCMS GAHMJ LAQJX EMDBF LPGKC. -VZKMG NQFCC ML
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Revelation Dec 24 2006, 11:00 AM Post #2
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 Welcome to the forum :)

I am trying to crack it, but the IOC doesn't give good results.

My guess is that the key length is: 9
RRRREJMEEEEEPVKLWENFNVJKEEEEEAOLKAFKLXCFZAASDJXZTTTTTTTLSIOWJXMOKLAFJNNKFNXN
RAGRBAQEMHIGDJVDSEOXVIYCELFHWLELJFIENXLRATALSJFSLCYTKLASJDKMHGOVOKAJDNMNUITN
RRRRLJVEEEEECLYVYHNVPFTAEEEEEMWLMEIRNGLARWJAKJDFLWNTIERJMIPQWOTZEOCXKNUBNXCN
RJIRPOWEANFUSNCZVDVZNMSFEKLOEPZLDKDJWSAAAAAAAOERHJCTNCKFRIMVKSOFOMKMANREWNBN
RZUDRGXEEEEENFQIDVLQNCKNEEEEEDGLLLLLLAWIOSNCDARLODMTOEJXMILDFJROTKJSDNLVCZNN
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Zofc Dec 24 2006, 11:12 AM Post #3
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 Thank you for the greeting.

**Unfourtanatly I wasn't thinking clearly and I made the key much longer. I probably shouldn't have done that for my first challenge because I know (at least for me) that when somebody works on the same code for a really long time due to the keylength, eww, it turns distasteful. If you want the keylength its: 18
yeah sorry about that.
FZZIX IMAEG GVTHX ENFHR FTPKB LLDIA ZAAGC WHMJV FRCMS GAHMJ LAQJX EMDBF LPGKC. -VZKMG NQFCC ML
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Revelation Dec 24 2006, 11:38 AM Post #4
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 Oh my, 18! The IOC gave me 36 as best possibility. So I figured the key would fit a number of times in 36, but some checking turned out that the key should be longer than 8. So I guessed 9, because that fits in 36. I guessed wrongly :P

Thanks for mentioning the key length. :)

Quote:
 
yeah sorry about that.


No problem :)
RRRREJMEEEEEPVKLWENFNVJKEEEEEAOLKAFKLXCFZAASDJXZTTTTTTTLSIOWJXMOKLAFJNNKFNXN
RAGRBAQEMHIGDJVDSEOXVIYCELFHWLELJFIENXLRATALSJFSLCYTKLASJDKMHGOVOKAJDNMNUITN
RRRRLJVEEEEECLYVYHNVPFTAEEEEEMWLMEIRNGLARWJAKJDFLWNTIERJMIPQWOTZEOCXKNUBNXCN
RJIRPOWEANFUSNCZVDVZNMSFEKLOEPZLDKDJWSAAAAAAAOERHJCTNCKFRIMVKSOFOMKMANREWNBN
RZUDRGXEEEEENFQIDVLQNCKNEEEEEDGLLLLLLAWIOSNCDARLODMTOEJXMILDFJROTKJSDNLVCZNN
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jdege Feb 18 2007, 03:57 AM Post #5
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 I took a fast look at this, when it first came up, with no luck. Even knowing the key length, nothing fell out. I'd pretty much convinced myself it used a mixed alphabet.

I just came back to it, for a bit, today, and discovered I was wrong. Plain vigenere, it's just that the stats were misleading me.

Code:
 
letter   cyphertext  Agatha Christie Novel
E        11.1%       12.6%
O        10.4%        7.6%
A         8.4%        7.6%
I         8.4%        6.7%
T         8.1%        9.5%
L         5.8%        4.0%
N         4.9%        6.6%
R         4.9%        5.6%


Not one of those intentionally deceptive texts, just normal deviation from the mean.

begin spoiler

Fifteen isn't too young. I worked through Katherine Yurica's Cipher File when I was thirteen. Didn't have anybody to tell me about Vigenere, though. So I didn't discover that until I was a junior in High School.

end spoiler
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
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Revelation Feb 18 2007, 11:39 AM Post #6
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 Did you use an application to crack it? I found it hard to find the right shifts.
RRRREJMEEEEEPVKLWENFNVJKEEEEEAOLKAFKLXCFZAASDJXZTTTTTTTLSIOWJXMOKLAFJNNKFNXN
RAGRBAQEMHIGDJVDSEOXVIYCELFHWLELJFIENXLRATALSJFSLCYTKLASJDKMHGOVOKAJDNMNUITN
RRRRLJVEEEEECLYVYHNVPFTAEEEEEMWLMEIRNGLARWJAKJDFLWNTIERJMIPQWOTZEOCXKNUBNXCN
RJIRPOWEANFUSNCZVDVZNMSFEKLOEPZLDKDJWSAAAAAAAOERHJCTNCKFRIMVKSOFOMKMANREWNBN
RZUDRGXEEEEENFQIDVLQNCKNEEEEEDGLLLLLLAWIOSNCDARLODMTOEJXMILDFJROTKJSDNLVCZNN
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jdege Feb 18 2007, 01:23 PM Post #7
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Revelation
Feb 18 2007, 11:39 AM
Did you use an application to crack it? I found it hard to find the right shifts.

Yes. And the applications I tried weren't finding the right shifts.

I'd been looking for a playfair cracker called fairplay, which I'd seen a number of references to. I used Google to search usenet, and found a post from 2001 where Joe Peschel announced having posted ""Fairplay," a Playfair cracker, by Gunnar Andersson".

I have to interject, though, that I find Google Groups a far less interesting name that Deja News.

In any case, Joe Peschel's website was hosted by AOL, and it's not there, anymore. But there used to be this site called "The Wayback Machine", and google told me that this was still around, though it had been renamed to "The Internet Archives". (What is it with throwing away all the old, interesting names, for bland, suit-friendly tripe?)

In any case, the fairplay source was available there, as were a number of other programs. Several of which were vig solvers. Since I'd this challenge was a vig I hadn't broken, I tried a few of them. None of them worked, entirely. But one, Fauzan Mirza's vigsolve, instead of displaying the cracked text, displayed the best-matched keyword for each key length. After a minor edit to search to keywords up to 25 characters, instead of 15, it clearly showed 18 has having the highest index of coincidence. And the best-matched key was clearly english text in many positions. I guessed the other positions from context, and turned out to be right.
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
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Donald Feb 19 2007, 01:50 PM Post #8
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 MUST... GET.... MORE... TIME... FOR... CRYPTO!!!!! :)
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jdege Feb 19 2007, 06:33 PM Post #9
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Donald
Feb 19 2007, 01:50 PM
MUST... GET.... MORE... TIME... FOR... CRYPTO!!!!!  :)

There's always time for crypto. There just isn't enough time for everything else.

You know, what fascinates me is how one automated tool can break easily a problem that another automated tool simply chokes on - and how for a different text things can be the reverse.

Understanding what it is that makes an automated approach suceed or fail is a fascinating question.
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.
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Zofc Jul 23 2007, 02:39 PM Post #10
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 Wow I was just glancing around and I only saw 3 of these replies. "My Assistant" didn't tell me that there were new posts in here. Sorry everybody. Actually I personally don't use any cryptography tools unless I absolutely have to (only 3 times in my life). I do all the enciphering and deciphering by hand. Yeah I know that's a lot of work (and paper) and what's the point when a computer can do it instantly? Well even though I'm a huge computer nerd, something appeals to me when it comes to breaking by hand. I guess it feels classical or something to me.
FZZIX IMAEG GVTHX ENFHR FTPKB LLDIA ZAAGC WHMJV FRCMS GAHMJ LAQJX EMDBF LPGKC. -VZKMG NQFCC ML
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