[Cryptech Tech] ent for rosc entropy in the Xilinx FPGA

[Bernd Paysan]

Am Montag, 8. Dezember 2014, 22:09:35 schrieb Fredrik Thulin:
> On Monday, December 08, 2014 10:03:06 PM Bernd Paysan wrote:
> ...
> 
> > > Optimum compression would reduce the size
> > > of this 67121200 byte file by 0 percent.
> > > 
> > > Chi square distribution for 67121200 samples is 227.52, and randomly
> > > would exceed this value 89.14 percent of the times.
> > 
> > That could be higher...
> 
> If it behaves like the avalanche noise sources I've been testing, it would
> likely rise a bit with more data (Joachim only had 67 Mbytes when he ran the
> tests it seems).

The Chi square test should be around 50% for whatever number of samples you 
have.

> > > I'm doing extraktion of more data. And if anybody wants the current raw
> > > data to do further analysis just tell me.
> > 
> > Sure, where can I get it?  A histogram plot over the bytes is the thing I
> > do first to check if there's something odd; from the ent results, there
> > probably isn't.
> 
> You've got a Novena, right? Maybe Joachim can send you a dump of what you
> need to get the rosc into your device.

Yes, that would work, too.

> If you are interested in more than the rosc, I would gladly make a prototype
> noise source board for you - although I'm out of PCBs at the moment. Are
> you going to 31c3?

Yes, I'm going to 31c3, giving a talk on the #wefixthenet self-organized 
podium.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/