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From: mlm@nl.cs.cmu.edu (Michael Mauldin)
Newsgroups: sci.crypt
Subject: Question about choosing E & D in RSA encryption
Message-ID: <15@nl.cs.cmu.edu>
Date: Mon, 13-Jul-87 01:08:51 EDT
Article-I.D.: nl.15
Posted: Mon Jul 13 01:08:51 1987
Date-Received: Tue, 14-Jul-87 00:48:06 EDT
Organization: Carnegie-Mellon University, CS/RI
Lines: 13
Keywords: RSA encryption fast

Does choosing E to be a power of 2 work for RSA encryption?

If E = 2**k, then exp(M,E) mod N is just k squarings of M (mod N).

This could reduce the number of multiplications necessary for encryption
by an average of 33%  (the decryption would still take as long, since
Dalmost certainly not be a power of 2).

Does this weaken the algorithm in any way?  Has someone already suggested this?

Michael L. Mauldin (Fuzzy)		Department of Computer Science
ARPA: Michael.Mauldin@NL.CS.CMU.EDU	Carnegie-Mellon University
Phone: (412) 268-3065			Pittsburgh, PA  15213-3890