[46195] in Cypherpunks
Re: Is this as insecure as it sounds (was FWD: Complete Fax Privacy Draws C
daemon@ATHENA.MIT.EDU (Simon Spero)
Sun Dec 31 18:29:04 1995
Date: Sun, 31 Dec 1995 15:22:09 -0800 (PST)
From: Simon Spero <ses@tipper.oit.unc.edu>
To: "Alan L. Bostick" <abostick@netcom.com>
Cc: cypherpunks@toad.com
In-Reply-To: <199512312219.OAA03598@netcom17.netcom.com>
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))))
