From: Matt Thomlinson <mattt@microsoft.com>
Date: Fri, 13 Jan 95 16:03:53 PST
To: cypherpunks@toad.com
Subject: FW: How do I know if its encrypted?
Message-ID: <9501140004.AA21059@netmail2.microsoft.com>
MIME-Version: 1.0
Content-Type: text/plain



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From:  <Ben.Goren@asu.edu>
To: Matt Thomlinson
Subject: Re: How do I know if its encrypted?
Date: Friday, January 13, 1995 12:27PM

At 9:35 AM 1/13/95, Matt Thomlinson wrote:
>make "handful of plaintext"  - > "hash of the plaintext" and you've got
>yourself
>a decent system. :)
>
>(this way, alice can keep a hash of the plaintext, hash of the ciphertext, and
>a key around for recovery, without keeping ANY plaintext. Also, for someone
>to request the data, knowing part of the message won't work; now they've
>got to know the entire message to recreate the hash.

That would be a little more secure, but I'm thinking that the "handful of
plaintext" would be a random number of some kind that the user prepends to
the file before encrypting. This is kinder on the data haven's CPU; compare
even 3DES of, say, 256 bits to IDEA of a few megabytes followed by MD5 of
same. Plus, it offers the operater even more deniability: he doesn't even
look at the whole file, but just enough to be sure that it's what it's
supposed to be.

Presumably, the data haven will specify how much a handful is, and offer a
client program that generates all this automatically.

>matt

You sent this to me privately, so that's how I'm replying. If you don't
mind, though, please forward this on to the list.

b&

--
Ben.Goren@asu.edu, Arizona State University School of Music
 Finger ben@tux.music.asu.edu for PGP public key ID 0xCFF23BD5.