[Cryptech Tech] dev-bridge board

[Paul Selkirk]

On 11/17/2015 02:28 AM, Joachim Strömbergson wrote:
> The status bit order can easily be changed, no problem.

I initially backed off because different cores do it differently.

rosc_entropy.v:
  tmp_read_data[STATUS_ENTROPY_VALID_BIT] = internal_entropy_valid;

avalanche_entropy.v:
  tmp_read_data = {31'h00000000, entropy_valid};

trng_csprng.v:
  tmp_read_data = {30'h00000000, ready_reg, rnd_syn};

Note in the last case, the "ready" flag is never actually set, and it's
unclear what it would be used for. (In the hash and cipher cores,
"ready" means it's ready for new input, but the rng cores are output-only.)

> When it comes to the entropy providers and esp the rng, one should
> _always_ check status before reading. Even if its hardly worth asking.
> This is something we should stress in the documentation.

Okay, fair enough.

				paul