[Cryptech Tech] trng ready for play

[Joachim Strömbergson]

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Aloha!

Bernd Paysan wrote:
> Multiple instances seeded with their own seed.  Actually, when you
> generate random numbers, the deterministic scalability of ChaCha is
> not needed - you only need that for cryptography (and there, you'd
> need scalable authentication to scale as well - e.g. tree hash based.
> The issue with a stream cipher is that you need another run over the
> data to get the authentication, unless, of course, you are only
> interested in random numbers).

Good point. There is one reason we want to have the deterministic
scalability is for testing. Given a specific seed we must be able to
generate a given sequence to allow somebody testing the design to get
the sequence they expect. But that would be solvable by allowing seeds
for all instances and then state the order from which we extract each data.

And no, in the trng we are only interested in generating random numbers.
Authenticated encryption would be another core (or two).


>>> I'd love to have a Keccak primitive in a CPU core with 1 cycle
>>> per round, giving about 5 bytes per cycle...
>> Which would be slower than running ChaCha in SW for long sequences.
>> ;-)
> 
> Well, the independently seeded per-core generators would still allow
> each core to emit 5 bytes per cycle - 0.2 cycle per byte,
> considerably faster than ChaCha in software.

Yeah, sorry I read your numbers as 5 cycles/byte.

- -- 
Med vänlig hälsning, Yours

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