[3104] in cryptography@c2.net mail archive
Re: practical encryption
daemon@ATHENA.MIT.EDU (Bill Frantz)
Tue Jul 28 10:43:35 1998
In-Reply-To: <199807261440.AA08891@world.std.com>
Date: Mon, 27 Jul 1998 20:40:51 -0800
To: Dan Geer <geer@world.std.com>, "P. J. Ponder" <ponder@freenet.tlh.fl.us>
From: Bill Frantz <frantz@netcom.com>
Cc: cryptography@c2.net
At 6:40 AM -0800 7/26/98, Dan Geer wrote:
> The discipline of key management is one of the harder aspects of properly
> implementing a cryptographic system. ...
>
>To be sure. A proposition, then, about cryptographic
>systems as systems, i.e., including key management,
>might then be:
>
>You can have good crypto or you can have easy crypto
>but you cannot have good, easy crypto.
>
>We can now argue about definitions of "good" versus
>"easy" and in which beholder's eye these are evaluated
>perhaps recognizing that we of this list are no doubt
>unrepresentative.
Rather than good vs. easy, consider the range: better - good - OK - bad -
worse.
I think we can agree that good encryption algorithms with adequate key
sizes provide better protection than no encryption, even with the keys kept
"in the clear" on the local file system. Such a system should offer good
protection from passive (listen only) attacks.
Even though we know of many active attacks which can easily compromise such
a system, making the attacker go to the effort of an active attack greatly
increases the risk of the attack, and should deter some attacks. For an
example, consider the data vacuuming attacks where large quantities of
run-of-the-mill communications are scanned for certain key words.
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