From: Marc.Ringuette@GS80.SP.CS.CMU.EDU
Date: Tue, 26 Jan 93 11:46:37 PST
To: cypherpunks@toad.com
Subject: Re: Computerized OTP (was 5th AMENDMENT & DECRYPTION)
Message-ID: <9301261946.AA09982@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


thug@phantom.com (Murdering Thug) writes,
> A person I know is working on a computerized version of the OTP that
> extracts a truly random stream of bits from TV/RF static and massages it
> using a DSP to be highly variable (e.g.: no runs of 0's or 1's longer than
> 5 bits).

Cool!  You've managed to weaken the one time pad enough for someone to 
crack it!  [ I can collect statistics on the plaintext based on the fact
that if five zeroes occur in the OTP then the next bit is constrained to 
be one.  Of course, I don't have complete access to the OTP, but it's
an extremely useful statitistical foot-in-the-door.  ]

This failure occurred because your friend tried to create a number
sequence that is somehow "more random than random".  Such a sequence
is, by definition, weak.

-- Marc Ringuette (mnr@cs.cmu.edu)