[Cryptography] Photon beam splitters for "true" random number generation ?

John Denker jsd at av8n.com
Sun Dec 13 19:44:23 EST 2015

```On 12/13/2015 12:19 AM, Ron Garret wrote:

> there are much easier ways to avail yourself of (essentially) the
> same physics.  Thermal noise, for example, gives you just as much
> “true randomness” as quantum measurements

Very true.

On 12/13/2015 02:43 PM, Hanno Böck wrote:

> Essentially what you're doing is you create a complex physical device
> for a non-problem. Use a good PRNG and you're fine.

Very untrue.

In reality, every PRNG requires a seed ... whereupon you have reduced
the task to the problem previously *NOT* solved:  where are you going
to get the seed????

> There are very few
> problems with random numbers and complicated physics devices don't solve
> any of them.

There is a long and sordid history of problems with random number
generators.

The physics doesn't have to be complicated, but it is absolutely
necessary for generating true randomness ... necessary for seeds
and for other high-grade applications.  You can't do it with physics
alone or with algorithms alone;  you need both.

BTW, as I have said before:
There is no such thing as a "random number".
If it's random, it's not a number.
If it's a number, it's not random.
You can have a random distribution over numbers, but then
the randomness is in the distribution, not any any particular
number that might have been drawn from such a distribution.

Or as John von Neumann put it:
Anyone who considers arithmetical methods of producing
random digits is, of course, in a state of sin.  For, as has been
pointed out several times, there is no such thing as a random
number -- there are only methods to produce random numbers, and a
strict arithmetic procedure of course is not such a method.
```