Carl Ellison on 'The Death of DES'

[Carl Ellison]

>Date: Wed, 29 Sep 1993 08:56:21 -0600 (MDT)
>From: Michael Johnson <mpj at csn.org>
>Subject: Re: Carl Ellison on 'The Death of DES' 
>To: Mike McNally <m5 at vail.tivoli.com>
>In-Reply-To: <9309291229.AA11549 at vail.tivoli.com>
>Message-Id: <Pine.3.05.9309290818.A2965-b100000 at teal.csn.org>

> In other words, des | tran really
>isn't much stronger than des

des | tran is exactly as secure as des.  A final tran adds nothing.  It
looks messed up to a human, but there's no cryptographic value added.

tran is of value *only* between two strong ciphers and its only value is to
increase the size of the block affected by the surrounding ciphers.

> , but des|tran|des|tran|des|tran|des|tran...
>could be quite strong (not to mention slow).

Try the new tran. The one originally posted had a slow (LC) PRNG.
The new one uses subtract-with-borrow and it's faster.

Another consumer warning:  the s-w-b PRNG has a huge period but that doesn't
make it cryptographically secure.  If anything, this is probably the easiest
PRNG to break.

 - Carl