From: Bill Stewart <stewarts@ix.netcom.com>
Date: Thu, 28 Aug 1997 07:27:17 +0800
To: Anonymous <anon@anon.efga.org>
Subject: Re: PGP5i supports RSA keys?
In-Reply-To: <19970817123643.13713.qmail@hotmail.com>
Message-ID: <3.0.2.32.19970826232116.02f656cc@popd.ix.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain



At 08:13 PM 8/24/97 -0400, Anonymous wrote:
>Sorry, but computer hardware performance is increasing exponentially,
>but the difficulty of factoring is subexponential in the length of the
>number.

Ok, it's subexponential, but not _very_ subexponential.
For example, doubling the work to crack a 1024 bit key means adding
about 10 bits, if I remember right; it's something like
2**N / log N or 2**(N/3) or some other relationship that's
close enough to exponential in that adding a small number of bits 
doubles the workload, for values of "small" that mean it doesn't take
you a substantially different amount of work to double the amount of
work a cracker needs to do, or multiply it by 1024, or by 1048576.
You can still kick the NSA's butt at the cost of going to next year's
model for your palmtop, or adding a few megahertz into your Pentium,
rather than needing to siphon off spare CPU cycles from Ft. Meade to
make your cellphone encryption fast enough.

#			Thanks;  Bill
# Bill Stewart, +1-415-442-2215 stewarts@ix.netcom.com
# You can get PGP outside the US at ftp.ox.ac.uk/pub/crypto/pgp
#   (If this is a mailing list or news, please Cc: me on replies.  Thanks.)