rough calculations

Lee Sonko (lee@networks.bgs.com)
Fri, 4 Apr 1997 15:05:16 -0500 (EST)


I just wanted to verify a couple numbers.....

Here are some rough calculations....

assumptions:
the Cray T3E-900 supercomputer can do 1.8 teraflops
http://www.cray.com/PUBLIC/WHATS_NEW/PRODUCTS/CRAY_T3E-900.html
a Pentium 120 runs at about 100 MIPS
http://www.bsdi.com/white-papers/becoming-an-isp-kolstad.html

ASS-U-M-ing 1 flop = 1 mip....

100,000,000 1
------------------- = ---------------
180,000,000,000,000 1,800,000

BEWARE: MIP numbers can be extremely unreliable but the order of magnitude is about
right

a Pentium 120 running linux (about 100 MIPS) and DESCHALL can break 600,000 keys/sec
a Cray Cray T3E-900 supercomputer can do 1.8 teraflops and break
600,000*1,800,000= 1080000000000 keys/sec

There are 72,057,594,037,927,936 DES keys
http://www.law.miami.edu/c6.html

1 Pentium 120 hunting 600,000 keys/sec will take 120095990063 seconds
or 3808 years to hunt the entire keyspace.

4.5 million P120's would crank out 2700000000000 keys/sec and hunt the entire
keyspace in 7 hours.

1 Cray T3E-900 hunting
600,000*1,800,000=1080000000000 keys per second will hunt the entire keyspace
in 18 hours.

The MIPS vs FLOPS thing could be off by up to 2 orders of magnitude, but, at it's
worst, the cray can crack DES in 1800 hours= 75 days