From: Llywelyn <samman@CS.YALE.EDU>
Date: Wed, 4 May 94 13:39:40 PDT
To: Brian D Williams <talon57@well.sf.ca.us>
Subject: Re: one time pad plus
In-Reply-To: <199405041946.MAA24810@well.sf.ca.us>
Message-ID: <Pine.3.07.9405041631.Q24376-b100000@jaguar.zoo.cs.yale.edu>
MIME-Version: 1.0
Content-Type: text/plain


>  Basically it would work like this; Thelma is looking to pass a
> message to Louise, so she XOR's plaintext file A against random
> byte file B producing ciphertext file C. Now since Thelma works for
> an unethical company that like to read it's employee's E-mail,
> she's in need of some "plausible deniability."
> 
>  Enter "One Time Pad Plus." Thelma now XOR's ciphertext file C with
> "Safetext" file D (any typically company approved useless memo)
> producing "pseudorandom" file E. She now copies random file B to
> disc and sends it to Louise via secure sneakernet. Then she
> performs a military grade wipe on A and B. Now she can send
> ciphertext file C via company E-mail.
> 
>  If her message is intercepted, she has deniability, she can claim
> she has read of hackers, cypherpunks, and other evils equipped with
> packet sniffers, and being concerned about security is using
> encryption. She can then produce "random" file E  and decrypt
> ciphertext file C which will yield not A but D the company approved
> useless memo.

Ok, I'm new to this crypto bit so I probably will have more mistakes here than
correct answers.  Anyways I'm going to give a shot.

1)If you have the secure channel(sneakernet) that you have to re-init each time
you use th eone time pad, then this will be most likely a novelty, since Lousie
could have slipped Thelma the plaintext when she slipped her the pad.

2)If you're using a pad like this, if I'm not mistaken isn't this what Kahn
calls a 'book cipher' where it would be simpler to crack than a true one time
pad that is truly random.

3)Thelma could have used stenographic technology to send the same information,
she could have used faxes that when decoded could yield a message(kinda like
the old punch cards)

Anyways, this is just the view of a complete rank amateur.  Give me feedback
y'all.

Ben.
____
Renegade academician. They're a dangerous breed when they go feral.
 		-James P. Blaylock in "Lord Kelvin's Machine"