From: Matthew J Ghio <mg5n+@andrew.cmu.edu>
Date: Thu, 14 Oct 93 16:57:03 PDT
To: cypherpunks@toad.com
Subject: Re: DES
In-Reply-To: <Pine.3.07.9310140846.A20680-a100000@hopper>
Message-ID: <QgjSNm200awV4XWVk7@andrew.cmu.edu>
MIME-Version: 1.0
Content-Type: text/plain


Jamie Jamison <jamie@apl.washington.edu> wrote:

> Two questions about DES. 
>
> 1) If the current, 56 bit, DES system is so easy to break why don't people
> switch over to a DES system that uses a larger key space, say 128 bits?
> People obviously aren't, so what's the barrier to this?

It's not easy to break.  It is possible to break it with about $1
million worth of specialized computing hardware.  Many programs, such as
PGP, do use larger keys.

> 2) How much longer would it take to break triple DES versus standard DES
> using one of the key-breaking machines described?

If all combinations had to be tried, it would take 2^112 times longer to
break a triple DES (168 bit) code than to break the standard 56 bit code.