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1996-01-01 - Re: Is this as insecure as it sounds (was FWD: Complete Fax Privacy Draws C

Header Data

From: Simon Spero <ses@tipper.oit.unc.edu>
To: “Alan L. Bostick” <abostick@netcom.com>
Message Hash: 2db26b6a66266c7aab10d140b7b9213b7099b99fc371f2501f5c0cce848f0c3f
Message ID: <Pine.SOL.3.91.951231151435.902C-100000@chivalry>
Reply To: <199512312219.OAA03598@netcom17.netcom.com>
UTC Datetime: 1996-01-01 00:07:52 UTC
Raw Date: Mon, 1 Jan 1996 08:07:52 +0800

Raw message

From: Simon Spero <ses@tipper.oit.unc.edu>
Date: Mon, 1 Jan 1996 08:07:52 +0800
To: "Alan L. Bostick" <abostick@netcom.com>
Subject: Re: Is this as insecure as it sounds (was FWD: Complete Fax Privacy Draws C
In-Reply-To: <199512312219.OAA03598@netcom17.netcom.com>
Message-ID: <Pine.SOL.3.91.951231151435.902C-100000@chivalry>
MIME-Version: 1.0
Content-Type: text/plain


If the plastic sheet is just a fixed mask, then this scheme yields 
instantly to chosen  plain-text (just send an all-black page), really 
quickly to known-plaintext, and pretty quickly to multiple cyphertexts.

There's got to be more to it than that

Simon

(defun modexpt (x y n)  "computes (x^y) mod n"
  (cond ((= y 0) 1) 	((= y 1) (mod x n))
	((evenp y) (mod (expt (modexpt x (/ y 2) n) 2) n))
	(t (mod (* x (modexpt x (1- y) n)) n))))

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