[Cryptography] TRNG review: Arduino based TRNGs

[dj at deadhat.com]

> I fail to see what possible use a > 1bps entropy source would have in
> an arduino-like environment.

There probably isn't. There certainly are datacenter applications for
multi gigabit random number generators and we make those. But sources for
resource constrained chips are in the 10s of megabits/s and are switched
off most of the time. The speed is usually a function of the clock speed
of the device. E.G. 100MHz, 8 clocks per bit => 12.5Mbits/s.

Where the need for random bits is low, there is no longer a need for a
DRBG/PRNG. A source and extractor will be sufficient.

In either case, an entropy source is the thing you can't do without, be it
fast, slow, fully or partially entropic, you need something. The rest you
can fix up with algorithms.

>
> Even if you want high-quality randomness for your Internet of Trash
> application, a few hundred bits over its lifetime will do.
>

Storing state is often a problem in resource constrained chips. A few
hundred fresh random bits per power cycle is more practical.

I know why the term IoT is popular. I get weary of typing "resource
constrained" all the time.