[Cryptech Tech] Suggested changes to TRNG

[Benedikt Stockebrand]

Hi folks,

Basil Dolmatov <dol at reedcat.net> writes:

> How one can be sure that this is enough? 
>
> Warmup delay is a possible solution to give system _some_ time to
> start, but should not be the only reason to consider entropy output as
> usable.
>
> Tests should be performed to make sure that the output has good quality and can be used. 

once again catching up with things...

Anyway, what I've done with the ARRGH firmware was to wait until I've
seen all 256 byte values from the source and only then start passing
random data out.

This is probably a bit over the top, but it's still reasonably fast to
start up.  It's reasonably easy to do in an MCU; don't know about FPGAs,
though.

Using a fixed interval is a bad idea because a fixed interval won't
adapt to tolerances of the components etc.  This is somewhat similar to
the reasoning why I rather measure the time between rising edges than
XORing a fixed number of readings.


Cheers,

    Benedikt

-- 
Benedikt Stockebrand,                   Stepladder IT Training+Consulting
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