From: "George A. Gleason" <gg@well.sf.ca.us>
Date: Fri, 18 Jun 93 02:25:06 PDT
To: tk@reagan.ai.mit.edu
Subject: Re:  Contempt of court
Message-ID: <93Jun18.022436pdt.14012-3@well.sf.ca.us>
MIME-Version: 1.0
Content-Type: text/plain


One-time pads for coerced confessions: 

Consider that the cyphertext of an OTP could come from *any* combination of
plaintext and keystream.  Okay, now you have in hand your cyphertext of an
original file having to do with your lawsuit against the govt.  Take that
cyphertext, and get another file of equal or longer length which is
completely innocuous, for instance some mild-sounding diary entries or some
such.  Now XOR these together, and what pops out is the *keystream* which
*would have been used for encyphering the innocuous plaintext into the
cyphertext you have there.  Okay, now you have five files:

1) your original plaintext re your lawsuit against the govt.
2) the keystream which converted that into the cyphertext below.
3) the cyphertext.
4) the innocuous text file for instance edited journal entries.
5) the "keystream" which resulted from XORing (3) and (4), which can be
claimed to be the keystream which was used to encypher (4) into (3).

Okay, now Big Brother comes to get you and coerce you to decypher your file,
but you don't want your attorney-client confidentiality violated, so you
hand over items (3) and (5), and when Big Bro "decrypts" (3), out pops (4)
thereby proving that you aren't the dastardly subversive who is trying to
sue the govt...!  "Dear diary..."
-gg