[Cryptech Tech] Alpha board main CPU change

[Joachim Strömbergson]

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Aloha!

Jacob wrote:
> STM32F4429 -> STM32F429
> 
> The ARM M4 has RTC in it, so I guess the external RTC chip is now 
> redundant.

No. Better precision and compartmentalization so we ware keeping it.
Instead we might use both.


> Also, realizing that I don't have any of the credentials required to 
> enter into the sanctum sanctorum of the crypto world, and I know
> that this is bordering on heresy, but since M4 has a TRNG, will you
> trust it? If yes, what benefit is provided by the noise board, if
> any? If not, why would you trust the M4 to manage your external TRNG
> and FPGA

As others have stated. No, we wont replace our TRNG with the one inside
the M4. And note that the noise board is only one of our noise sources.

If the TRNG inside is the same design as in the STM32L06, based on
testing with Dieharder it generates good random numbers. But it is a
black box. ST does not provide any real information on what the
underlying physical process is, how it is used to drive a CSPRNG. And of
course to real insight into what is actually on the chip.

We could use the TRNG in the M4 as an entropy source to feed the TRNG
inside the FPGA (basically a FIFO into which SW could write words
consumed during entropy mixing). But replacing the TRNG, no.

- -- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
========================================================================
 Joachim Strömbergson          Secworks AB          joachim at secworks.se
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