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From: flackc@stolaf.UUCP (Chap Flack)
Newsgroups: net.crypt
Subject: Re: Re: Re: factoring algorithms and RSA public key code
Message-ID: <5138@stolaf.UUCP>
Date: Fri, 7-Mar-86 16:22:19 EST
Article-I.D.: stolaf.5138
Posted: Fri Mar  7 16:22:19 1986
Date-Received: Tue, 11-Mar-86 00:26:13 EST
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Organization: Carleton College, Northfield, MN
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> >In this particular case, the problem is not provably hard (at least, I
> >haven't heard of a proof), but the idea is that you *can* imagine
> >a cryptosystem that would not depend on the enemy's ignorance.
> Almost right.  You ARE depending on the enemy's ignorance of your private
> key, aren't you?-- 

What's more, I'm depending on the enemy's ignorance of the original
plaintext of the message I'm trying to send!  :-)

Does this mean that cryptology is a useless field?  No.  Through
cryptology we are trying to protect information that has to be
distributed and is therefore subject to interception.  There are
all sorts of ways to protect information that doesn't have to go
anywhere (such as my original message and your private key)--these
are physical security considerations, and needn't concern
cryptologists.

As for the physical security of the private key,
Rivest, Shamir, and Adleman suggested one approach in their original
paper:  All of the logic for generating keys and {en/de}crypting
messages is put into a dedicated piece of hardware with a physically
secure cabinet.  It generates your two keys for you, tells you one
of them, and saves the other one internally in order to do the
decryption.  Your private key never leaves the box.  If the cabinet
is tampered with, the memory is erased.
-- 
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Chap Flack				ihnp4!stolaf!agnes!flackc
Carleton College			ihnp4!stolaf!flackc
Northfield, MN  55057