[Cryptech Tech] Dieharder test of Cryptech RNG data

Benedikt Stockebrand bs at stepladder-it.com
Wed Apr 8 07:04:02 UTC 2015


Hi Pavel and list,

Павел Шатов <meisterpaul1 at yandex.ru> writes:

> I also don't quite understand why charge pumps are used? As far as I
> know, they have very limited output current, while during avalanche
> breakdown large current flows through transistor. Is this okay?

there are current limiting resistors in place, but other than that
Fredrik opted for the charge pump because it seems to generate less
ripple than a boost converter.

Unlike hime I personally prefer the boost converter for a number of
reasons, but this is one of the reasons why I like modular designs where
these things can be individually modified or replaced.

> What signal is fed into FPGA, btw? TP19 ("AMPLIFIED")? Is it okay to
> feed analog signal into digital input buffer?

I don't know about FPGAs, but when I built my stuff I eventually took a
very close look at the MCU datasheets, concerning voltage thresholds and
such.

Going Fredrik's way and using Schmitt triggers is more modular than
relying on the specs of the particular MCU or FPGA, but it adds some
extra complexity.


Cheers,

    Benedikt

-- 
Benedikt Stockebrand,                   Stepladder IT Training+Consulting
Dipl.-Inform.                           http://www.stepladder-it.com/

          Business Grade IPv6 --- Consulting, Training, Projects

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