From: Scottauge@aol.com
Date: Tue, 20 Aug 1996 10:45:59 +0800
To: winsock@c2.org
Subject: Re: No Subject - Lesson in cracking (cryptoanalysis 001)
Message-ID: <960819193406_263572605@emout14.mail.aol.com>
MIME-Version: 1.0
Content-Type: text/plain


In a message dated 96-08-19 05:44:34 EDT, you write:

> SAMPLE MESSAGE: ("HAIL ERIS")
>  
>  CONVERSATION:
>  A B C D E F G H I J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
>  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
>  
>  STEP 1. Write out the message (HAIL ERIS) and put all the vowels at the
end
>          (HLRSAIEI)
>  STEP 2. Reverse order (IEIASRLH)
>  STEP 3. Convert to numbers (9-5-9-1-19-18-12-8)
>  STEP 4. Put into numerical order (1-5-8-9-9-12-18-19)
>  STEP 5. Convert back to letters (AEHIILRS)
>  
>  This cryptographic cypher code is GUARANTEED TO BE 100% UNBREAKABLE.
>  
>  

Hmmmmm, lets see here....

The numbers are one to one with the letters - hence this suggests a frequency
attack right off the bat.  You see, poor pathetic soul, if we know the
algorithm, as you have spelt it out, and we know the alphabet of the
plaintext (thats the message your trying to protect), we know that the
language has certain letters used more frequently than others.  Like, ya know
"e" is a very popular letter, so is t and s.  Collect enough cypher text and
ya just match frequency to frequency - a high number of 6's are replaced with
an e, and so on down the line.

QED why you don't go one to one with the alphabet.

OK, so we got the letters we are interested in working with.  Now, still
knowing the language the alphabet represents, we know that certain letters
usually follow other letters.  For example, re, ent, th, st, ing, need I
really go on?

Now we just start chunking up the peices according to spelling rules we know
about - then with the help of a handy dandy spell checker like thing, when we
get close to a word, we clump the chunks together.

Actually, mixing your letters around helps cuz one needs to do a lot of
shuffling here - but believe me, algorithms are out there.  Plus, the more
cipher text you provide, the easier it is to nab your info cuz there is more
information for the particular algorithm I'm thinking of to work with.

Once ya get a likely set of words, ya start looking for a pattern that can
get ya these set of words into and gain the original pattern.

QED why one does not depend on shuffling for protection.

Anyone else wanna explain things too?