[Cryptography] A TRNG review per day (week?): ATSHA204A has low entropy

[Bill Cox]

On Thu, Dec 11, 2014 at 2:21 PM, R P Herrold <herrold at owlriver.com> wrote:
>
> On Tue, 9 Dec 2014, Bill Cox wrote:
>
> > I just did another simple test.  After cold-booting my Raspberry Pi, I
> > called "./haslet random" and recorded the 32-byte result.  I had the
> > update-seed parameter turned off
>
> Using an un-seeded RNG with the hashlet code requires patching
> out the protections which the code offers.  This seems a lot
> like complaining that it hurts when you stick a fork in your
> eye
>
> You were running something based on another's code, but
> after removing the in-built  guarding.  It is NOT:
>         ./hashlet random
>
> How is this a fair test?
>
> -- Russ herrold
>

Hi, Russ.  Especially if all you're using this device for is DRM of some
sort, feel free to use it exactly as Atmel recommends.  However, the EEPROM
seed is most likely a back-door.  I have to laugh at the phrased "unseeded
RNG" when talking about a hardware true random number generator.  There's
no such thing.

Bill
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