[Cryptography] Entropy Needed for SSH Keys?

[Tom Mitchell]

On Fri, May 27, 2016 at 5:53 PM, Sampo Syreeni <decoy at iki.fi> wrote:

> On 2016-05-27, Ray Dillinger wrote:
>
> IIRC, one nanosecond was once defined to me as the approximate amount of
>> time it takes for light to travel fifteen centimeters.
>>
>
> In vacuum (and mostly in dry air),
>
....

>
> Does this matter much, in terms of creating useful interference patterns?
>>
>
> In interference, it matters down to the twelfth digit.
>

Manufacturing  to the twelfth digit on a printed wiring board
would be a challenge nearly impossible.  So difficult that there
is a worthy nut of an invention to generate entropy.

A pair of modest wires of mildly dissimilar material would also
generate dynamics in the twelfth digit as the board temperature
changed.   A single patch wire could interfere with a PWB trace.
Multiple traces routed through different functional blocks would
see variability in temperature shift related length changes in the
12th digit as well.

Interesting idea especially when faithful reproduction of entropy sources
is
not a good idea especially when filtered and hidden behind a whitener
except for test.





-- 
  T o m    M i t c h e l l
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