From: Jim Gillogly <jim@acm.org>
Date: Thu, 17 Aug 95 15:20:08 PDT
To: cypherpunks@toad.com
Subject: Re: More on Netscape
In-Reply-To: <9508172151.AA14704@argosy.MasPar.COM>
Message-ID: <199508172219.PAA04481@mycroft.rand.org>
MIME-Version: 1.0
Content-Type: text/plain



Various people said:
> >It says that the commerce server supports (among others) DES and DES3
> >(same as 3DES?).  They list the key sizes as 64 and 192 bits
> >respectively.  My question is, isn't DES 56 bits?  (with an 8 bit salt
> >that would be 64 I guess), but isn't DES3 112 bits, not 192?

> DES keys are specified as 64 bits, of which 8 bits provide odd parity.
> The 192 bits would specify three independent keys (not triple DES)

Real-world DES implementations ignore those 8 "parity" bits.  DES uses
56 bits of key for encryption, and calling it a 64 bit key is misleading.

Triple DES (3DES) is an overloaded term.  It's used in 2- and 3-key
versions, for 112 and 168 bits of protection respectively.

	Jim Gillogly
	Highday, 25 Wedmath S.R. 1995, 22:18