Re: For the smart guys/girls/what-have-you here: "Towards a European quantum internet"

On a sunny day (Fri, 1 Nov 2024 17:55:03 -0700) it happened
dplatt@coop.radagast.org (Dave Platt) wrote in
<7s9gvk-13bh.ln1@coop.radagast.org>:

In article <vg1qja$lve$1@solani.org>,
Jan Panteltje  <alien@comet.invalid> wrote:
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Me:
I wonder, yes I wonder...
Not sure I understand it, not sure what it could do..
Anybody has a simple explanation?
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quantum??? has become some sort of sales word...
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ESP simpler?

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No, it's real.
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The idea here, I understand, is to use a system of entangled
photons, carried over a fiber-optic cable, to create a secure
system for doing encryption-key sharing/distribution between
cooperating endpoints.  Two data centers (for example) can use
such a link to create encryption-session keys for doing bulk
data transmission.
>
Doing secure key distribution is one of the big difficulties in
setting up data encryption.  The algorithms which perform the actual
encryption of large amounts of data (for example, AES-256) can handle
a lot of data (gigabits per second), and they're very strong and are
considered infeasible to break anytime soon.  However, they are
"secret key" algorithms - the sender and receiver each need to know
the same secret key (e.g. a 256-bit number).  You need a way of
enabling the sender and receiver to share a key (either one creates it
and sends it to the other, or they mutually derive it through some
sort of shared process) *without* anyone else being able to intercept
the key.
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In recent decades this sharing has usually been done through
"public-key" cryptography - for example, the RSA or ElGamal
algorithms.  Unfortunately, these algorithms are known to be
potentially open to attack by a "quantum computer" with a sufficiently
large number of qubits.  No such exist today, but it's suspected that
they may be developed within the next couple of decades.  Once that
happens, RSA-based keys will be insecure (and any communications which
were based on them today could be recorded, and eventually "broken" by
a quantum computer).
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There are new key-sharing/encapsulation algorithms being developed
for software use, which are _believed_ to be resistant to attack
by quantum computers, but they're still new, and there's always
the risk that improvements in quantum computing might render
these algorithms vulnerable.
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So, researchers are trying to create ways of key-sharing
which are fundamentally unbreakable/untappable, using
_physical_ techniques based on quantum entanglement.
You create entangled pairs of particles, send one in each
pair to your friend in the next city, and then do measurements
on your particles which enable you to (eventually) create a
key known to both parties.
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The advantage to this sort of approach is that (by current theory) it
should be impossible for any attacker to be able to "wire-tap" the
entangled photons being transmitted, and copy them (and thus be able
to reverse-engineer the keys being created).  Doing so would require
interacting with the entangled photon being transmitted, and break the
entanglement, and this would cause the secure key distribution
algorithm to fail.  In short, if you "peek" at the signal in the
cable, the key-sharing system immediately stops working and an alarm
goes off, and the people who "own" the cable will know immediately.
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The amount of data one can send over an entangled-photon link isn't
very high, but it doesn't need to be, since you'd be using it only
for secure key creation.

OK, very nice explanation, I knew that, recently posted something about that to sci.crypt,
been following that group for a long time. But what gets me in all this is
'entangled photons'
  https://en.wikipedia.org/wiki/Quantum_entanglement
I have come up with a different view for that,
from a wave point of view it is all very simple.
Albert Onestone's 'voteon' was a big mistake from the beginning if you ask me.
But is Albert E also wrong on lightspeed?
I personaly think gravity and light maye be carried by the same entety, maybe a Le Saga type particle.
But we are just like an ant in teh garde, few neurons to understand it all..
Mysterious action at a distance?
I you distribute a pair of shoes then if Alice far away finds a left side one
then Bob elsewere must have the right side one ...
Nothing mysterious about that.
Fishics is still stuck with A.E's light creeping speed, with graphitty, and mamaticians doing divde by zero.
If humming beens are not extinct by then, a few thousand years in the future the theories would / (could?)
be very different and would Trump have won again?

As to security, so many backchannel attacks are possible... plus some others I know about...
We ants....