From: daleh@ix.netcom.com (Dale Harrison (AEGIS))
Date: Thu, 12 Jan 95 07:38:43 PST
To: cypherpunks@toad.com
Subject: Re: Cryptanalysis
Message-ID: <199501121537.HAA01536@ix2.ix.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


You wrote: 

>If the encryption method is any good, the output will be pseudo-random
>with no digit being more frequent than any other. This certainly applies
>to IDEA and DES. With RSA, you usually have a random (IDEA) session key
>encrypted using the senders private key. This will also be an effectively
>'random' number.

Just a technical note, but a normal distribution of digits (i.e. 'no digit 
more frequent than any other') is no inidication of either randomness or 
'good' encryption.  A better test is to look for a normal distribution at 
all scale levels.  For example, the following text block: "UUU" (in ASCII) 
has a normal distribution at the bit level "0101 0101 0101 0101 0101 0101",
but not at the byte level.

Dale H.