From: mpd@netcom.com (Mike Duvos)
Date: Thu, 2 May 1996 20:08:25 +0800
To: cypherpunks@toad.com
Subject: Re: [Fwd: Cylink can export 128-bit DH?]
In-Reply-To: <3188382C.9778B7@cs.berkeley.edu>
Message-ID: <199605020644.XAA23770@netcom8.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


Raph Levien writes:

> Double DES is subject to a "meet in the middle" attack (not a "man in
> the middle"). 

Yes, a silly mistake on my part, which shows I should proofread even
the little messages before posting them. :)

Gleeful readers are filling my mailbox hoping to be the first to point
out this unfortunate error. 

> Thus, using
> three keys is more work for the attacker than using two. So, modern
> cryptographic usage is exactly as Bill said - three keys, three
> encryptions. For example, S/MIME recommends the use of DES-EDE3-CBC (the
> middle encryption is technically a decryption, although it doesn't
> really make any difference).

S/MIME aside, I was under the impression that the term "Triple-DES"
referred to the encrypt-decrypt-encrypt operation using two 
distinct keys, proposed by some for adoption as the successor to 
single DES. 

Has this usage now changed in favor of the three key version?

--
     Mike Duvos         $    PGP 2.6 Public Key available     $
     mpd@netcom.com     $    via Finger.                      $