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From: wiebren@botter.UUCP
Newsgroups: net.crypt
Subject: Re: Four key public cryptography?
Message-ID: <507@botter.UUCP>
Date: Mon, 3-Feb-86 09:49:22 EST
Article-I.D.: botter.507
Posted: Mon Feb  3 09:49:22 1986
Date-Received: Wed, 5-Feb-86 04:42:55 EST
References: <12900001@ccvaxa>
Organization: VU Informatica, Amsterdam
Lines: 19

You seem to be a 'victim' of the fact that most people present
the subject of secrecy and of authenticity (too much) intertwined.
This is caused by the fact that RSA can be used for secrecy as well
as for authenticity at the same time, since for RSA E.D=D.E=I.
(E.g., note that the secret deciphering transformation for the 'secrecy
application' is often denoted by D, but this bad identifier makes
that the same D denotes the secret encyphering (!) transformation to be used
for the 'authenticity application'.)
Since the RSA algorithm is a (resp., the most) well-known, famous, secure,
elegant, etc. public-key algorithm, it is (almost) always used to illustrate
the possibility of achieving authenticity as well as secrecy.
And thus in examples you will find only two keys.
However, any cryptographer is (should be) aware of the fact that
a public-key system not having the commutative property E.D=D.E
(but giving the choice to keep either the E or the D transformation secret)
still may be used for secrecy or authenticity, and that both
properties then can be achieved by using four keys instead of two.
In short, your idea of using four keys is OK, but contains no new
elements.