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From: billp@azure.UUCP (Bill Pfeifer)
Newsgroups: net.crypt
Subject: Re: One-time pads
Message-ID: <2540@azure.UUCP>
Date: Fri, 17-Feb-84 12:48:27 EST
Article-I.D.: azure.2540
Posted: Fri Feb 17 12:48:27 1984
Date-Received: Sun, 19-Feb-84 08:08:20 EST
Organization: Tektronix, Beaverton OR
Lines: 18

Gene Spafford writes:
>>	A difficulty is that in any truly random bit string, there is very
>>	possibly a run of M zeros, with M up to the size of the message.  That
>>	is, it is expected that at some time there will be a long enough run of
>>	zeros so as to not encrypt a major portion of the text.  In fact, it is
>>	entirely possible that a random key could be all zeros, thus producing
>>	an encrypted text equal to the plain text!

That is true.  However, we must look at the probabilities.  There is a chance
that a string of zeroes leaves a portion of the text unencrypted.
There is an *equal* chance that a certain combination of random digits
produces cleartext of opposite meaning, or text from a future OSHA regulation,
or a portion of a german poem.  In other words, if you find something readable,
in whatever language, in a message that has been encrypted with a one-time-pad
of *truly* random digits, it is equally meaningful as "skpebcvus;fjwuy*z".

	Bill Pfeifer
{cbosgd,decvax,harpo,ihnss,ogcvax,pur-ee,ucbvax,zehntel} !tektronix!tekmdp!billp