Path: utzoo!mnetor!uunet!husc6!mit-eddie!ll-xn!ames!umix!umich!mibte!gamma!pyuxp!pyuxww!sabre!faline!karn
From: karn@faline.bellcore.com (Phil R. Karn)
Newsgroups: sci.crypt
Subject: Re: how do you tell encrytped data from random data?
Message-ID: <1701@faline.bellcore.com>
Date: 11 Jan 88 23:30:16 GMT
References: <660@bucket.UUCP> <6992@brl-smoke.ARPA> <1499@osiris.UUCP> <7037@brl-smoke.ARPA>
Organization: Bell Communications Research, Inc
Lines: 25
Summary: Randomness, Decrypting the Bible

Re random and encrypted messages: There is a strong connection between
randomness and cryptography. "Randomness" is in the eye of the beholder.
All it means for you to say that something is "random" is that *you*
can't predict what the next element in the sequence is, not that it
doesn't contain some underlying redundancy that someone else with
additional information (or computing power) might discover.  It
therefore follows that any strong encryption algorithm would necessarily
produce what appeared to be totally random ciphertext. Feed a counter
into DES and you have an excellent random number generator;
unfortunately it is usually too slow to be practical.

> On the other hand, there are people such as those who find Baconian
> ciphers in Shakespeare's works, who put the message there themselves.
> It's pretty easy to tell when this happens; either the decipherment
> method is ambiguous, so the message could never have been
> realistically expected to be read even by its intended recipient,
> or so many "corrections" and otherwise unjustified special twists
> on the decipherment scheme have been introduced that the
> information content of the decipherment rivals that of the supposed
> message being extracted.

Quite true. I know I'm going to get flamed for this, but this is *precisely*
what people do all the time with the Bible.

Phil