Eugen Leitl wrote:
On Sat, Feb 19, 2005 at 03:53:53PM +0000, Dave Howe wrote:
I wasn't aware that FPGA technology had improved that much if any - feel
free to correct my misapprehension in that area though :)
FPGAs are too slow (and too expensive), if you want lots of SHA-1
performance,
use a crypto processor (or lots of forthcoming C5J mini-ITX boards), or an
ASIC.
Assuming, fast SHA-1 computation is the basis for the attack -- we do not
know that.
Indeed so. however, the argument "in 1998, a FPGA machine broke a DES key in 72 hours, therefore TODAY..." assumes that (a) the problems are comparable, and (b) that moores law has been applied to FPGAs as well as CPUs.
I am unaware of any massive improvement (certainly to the scale of the comparable improvement in CPUs) in FPGAs, and the ones I looked at a a few days ago while researching this question seemed to have pretty much the same spec sheet as the ones I looked at back then. However, I am not a gate array techie, and most of my experience with them has been small (two-three chip) devices at very long intervals, purely for my own interest. It is possible there has been a quantum leap foward in FPGA tech or some substitute tech that can perform massively parallel calculations, on larger block sizes and hence more operations, at a noticably faster rate than the DES cracker could back then.
Schneier apparently believes there has been - but is simply applying moore's law to the machine from back then, and that may not be true unless he knows something I don't (I assume he knows lots of things I don't, but of course he may not have thought this one though :)




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