[Cryptech Core] ModExp test results

[Joachim Strömbergson]

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Aloha!

Rob Austein wrote:
> I've been running some tests on the old (about a month ago) and
> latest (yesterday) ModExp core.  Results summarized below, notes
> follow.
> 
> 1024		2048		4096 
> --------------------------------------------------------------------------
>
> 
Old ModExp encrypt		5.837198	35.920986	267.222054
> Old ModExp decrypt		5.489668	35.583835	268.625344 Old CRT decrypt
> 14.142096	104.246679	802.028670 Old keygen/encrypt/decrypt	68.106694
> 679.259678	6305.303504
> 
> SW CRT decrypt			0.359630	0.396882	3.450447 SW keygen/encrypt/decrypt
> 2.406200	15.713556	377.959982
> 
> New ModExp encrypt		0.608936	[x] 0.497601	[x] New ModExp decrypt
> 3.711576	[x] 23.882598	[x] New CRT decrypt			9.749045	[x] 29.750953
> [x] New keygen/encrypt/decrypt	67.868772	[x] 512.707423	[x]
> 
> Notes:
> 
> - The [x] flags indicate cases for which the result was wrong.  The 
> new core handles 1024 bit keys correctly but returns all-zero results
> for 2048 bit and 4096 bit keys.

Ouch.

The numbers for 1024 bit operations is close to expected with the
optimizations committed so far, but all lengths should work. I'm doing
short exponent (encrypt) operations with 2048 bit modulus in simulation.
I will investigate why 2048 and 4096 does not work. Simulating 2048 bit
verification is hard, it takes days.

Working on more optimizations too and expect to complete the operand
size change the next couple of days. And I will continue to work until
this is done. It might be hard to reach parity with SW on Novena with
the size constraints of the FPGA. We would have to use at least 128 and
possibly 256 bit operands, and moving from 32->64->128->256 basically
doubles the number of slices needed in each step.

- -- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
========================================================================
 Joachim Strömbergson          Secworks AB          joachim at secworks.se
========================================================================
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