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From: outer@utcsri.UUCP (Richard Outerbridge)
Newsgroups: net.crypt
Subject: DES IP&IP-1: Correction?
Message-ID: <3389@utcsri.UUCP>
Date: Sun, 21-Sep-86 09:56:53 EDT
Article-I.D.: utcsri.3389
Posted: Sun Sep 21 09:56:53 1986
Date-Received: Sun, 21-Sep-86 10:15:47 EDT
Distribution: net
Organization: CSRI, University of Toronto
Lines: 18

Back in July there was a brief discussion of the DES IP and IP-1, to which
I contributed my cynical belief that their only function was to confound
software implementation of the DEA.

Leafing through >Cryptography< by Meyer and Matyas last night, the following
passage leaped out at me (I'd highlited it at some point) on page 116:

	"The initial and inverse permutations allow the algorithm to be
	implemented more easily on a single chip, provided that the data
	and the key are serially loaded."

So: 'officially' they're there to make single chip (circa 1976) serially-
loading hardware implementations easier.  Is anyone familiar enough with the
art of hardware (in 1976) and the DEA to opine whether or not this makes a
whole lot of sense?  Is that glass half-empty or half-full?
-- 
Richard Outerbridge	<outer@utcsri.UUCP>	 (416) 961-4757
Payload Deliveries:	N 43 39'36", W 79 23'42", Elev. 106.47m.