[Cryptech Tech] About the TRNG

[Basil Dolmatov]

dol@ с iPad

> 19 дек. 2015 г., в 1:22, Jacob <jacob at edamaker.com> написал(а):
> 
> 
> A question to the experts:
> 
> I fully understand the trust gained by having a custom made external analog TRNG as we do here, but wouldn't be better to XOR the bitstream received from our generator with the one embedded in the CPU(*)?
What means 'better' in this case?
Mixing two really good sources of entropy does not make output 'better' considering entropy quality.
This mixing can give one some hope that having mediocre entropy sources one can make the result better. 

Having a good source of entropy I can not see any reason for mixing it with other data.

> I mean, if the CPU 's TRNG is tainted, we will not be worse off, and if it is not, the board will probably exhibit higher security in case our generator would have some issues.
> 
> (*) from the STM32F429 datasheet: All devices embed an RNG that delivers 32-bit random numbers generated by an integrated analog circuit
> (analog noise feeding into a shift register)
> 
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