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Date: Tue, 21 Sep 2010 06:02:05 -0400
From: Rich Rumble <richrumble@...il.com>
To: john-users@...ts.openwall.com
Subject: Re: Substitution ciphers
I have a few plain-texts, and it's substitution for sure. I would look for a
probability rather than a concrete "this is the answer key". I've realized
just trying to break the cipher by hand that it's not like most simple ciphers
I've dealt with. This one must not be in order like most I've encountered
a-z 0-9... this one is like a 3 t 9 c & 2 z ~ " and so on...
Thanks for the tool suggestion, I'm looking at it now, pretty slick!
If anyone wants a challenge perhaps check out the plain-texts I do have
here: http://xinn.org/cipher2.txt
I thought since I know quite a few of the plain-text and the key's used that
it could be possible to figure out which order of what I think is a
vigenere cipher
block is in, at least in certain positions. But perhaps it's 68 to the 68th and
might not be worth it?
On Mon, Sep 20, 2010 at 12:47 PM, Charles Weir <cweir@...edu> wrote:
> Hey Rich,
> I really doubt that JtR could be configured to deal with this
> since you require a human to determine if the code was cracked or not.
> Aka you need to look at the plain-text and say, "ah that looks right".
> That's different from a password hash which JtR can check
> automatically, (hashing a guess and comparing it to the target hash).
>
> I highly recommend that you check out CrypTool. I've used it in a
> bunch of computer security challenges and had great success with it.
> You can visit the website at:
>
> http://www.cryptool.com/
>
> I still use the older version of it just because it's simpler for
> dealing with basic ciphers, (and I'm lazy), but if you are willing to
> learn some of the advanced features the newer version is pretty nice.
> They even have a web-only version though it's a bit limited. Just
> curious, do you know if you are dealing with a substitution cipher or
> a vigenere cipher? They are actually a bit different in that a
> vigenere cipher can encrypt the same letter differently depending on
> the key length, (technically a vigenere cipher with a key length of
> one is the same as a substitution cipher). Therefore, it's usually a
> pain to break smaller messages encrypted with it, (you need enough
> ciphertext to be able to perform frequency analysis on each
> substitution cipher in the vigenere cipher's key).
>
> Matt
>
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