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

Phillip Hallam-Baker phill at hallambaker.com
Mon Dec 14 20:18:57 EST 2015

On Sun, Dec 13, 2015 at 2:19 AM, Ron Garret <ron at flownet.com> wrote:

> On Dec 12, 2015, at 7:06 PM, Henry Baker <hbaker1 at pipeline.com> wrote:
> > I'm not a physicist, but I recall from my undergraduate days that one
> can produce a beam of essentially "pure" linearly polarized light.
> Furthermore, if one then splits this linearly polarized beam into two and
> passes one through another linear polarizer at 45 degrees and the other
> beam goes through a different linear polarizer also at 45 degrees to the
> first beam, but 90 degrees to the other polarizer, then each photon that
> gets through at all, must *randomly choose* whether it will align with the
> first polarizer or the second polarizer.

There was a booth at the 2013 RSA show where a company was selling one. I
forget the price.

The problem with such devices is that when you make a physical anything,
you end up with biases. And then when you try to correct for the biases you
lose the perfect theoretical security.

Like one time pads, quantum crypto is perfect in theory but the proofs tend
to be very brittle. I much prefer a system that isn't provably secure but
is demonstrably robust over one that is provably secure but has a single
point of failure.
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