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Joined: Oct 2004
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Quantum Cryptography is a dirty joke.

Do not count on it to be any good.
Neither Physics nor Math are correct.
A bad example of wishful thinking, that is.


ES



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Physics considerations are suspicious.

But the Cryptography considerations are yet worse.

The whole thing misses the fact, that it is not avoiding "man in the Middle" attack. The story about any evesdropping being detectable, is based on simple mistakes.

Let's say that Evesdropper has the same equipment as Alice and Bob.
He does not need just "listen without interference".

Instead, he receives signals from Alice, and issues randomly generated signals to Bob (recording them).

Now, he listens to the open conversation between Alice and Bob, about which encoding was used at each signal.

He knows then what Bob thinks the key is.
He knows what Alice thinks the key is.

Now, if he stays in the middle in keyed conversation, he simply must decode Alice's messages by her key, encode them by Bob's key, and send them out.
And vice versa: he must decode Bob's messages by his key, encode them by Alica's's key, and send them out.


Concusion is that Quantum Cryptography is impossible or detectable :P


es

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"Neither Physics nor Math are correct."
I assume you're talking about the physics and math of QC in particular and not making the generalization that all of physics and math is incorrect.

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The whole post is about Quantum Cryptography.
I am saying that its claims and assumptions are incorrect.

es

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As this is the physics forum, it seems appropriate that you would attempt to enlighten us by critiquing the flawed physics and perhaps a few incorrect equations.

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The claim which whole concept is based upon, is that Eavesdropper can not overhear surreptitiously photon's polarization because doing so he is going to change photon's state.

Granted that the incoming photon's state can/will change due to measurement. But since the information acquired through the measurement allows to recreate an equivalent to the Alice's original photon using the same equipment that Alice used - the original photon can be discarded after measurement, and its equivalent photon send out to Bob. Which amounts to successful Man-in-the-Middle attack.

The measurement by Eavesdrpper can be done by use of light amplifier, splitter, and of pairs of orthogonal polarization filters placed on each of the obtained sub-beams with 45 degree turn relative to each other.

Polarization of the original photon and the base that Alice used, will be indicated by the orientation of the filter that produces brighter light than its orthogonal twin.

By the way, using of such device by Bob would make the subsequent public conversation between Bob and Alice redundant, as its only purpose is to synchronize the bases of messages.


There is an another flavor of QCryptography algorithm that relies on the entanglement - which is just a pure pseudoscience.

ES


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Originally Posted By: extrasense
The claim.............................>

There is an another flavor of QCryptography algorithm that relies on the entanglement - which is just a pure pseudoscience.

ES



[quote=Mike Kremer]

You know the wonderful thing about science is that, you can produce an abundance of theorys.....but they dont become
"science" until the theory has been proven absolute.

Well it just so happens that Entanglement, and in particular Quantum entanglement is a fact.
Scientists regulary produce entangled Photons or atoms linked by the strange phenomenon known as entaglement.By altering the state of one particle, instantly alters the state of the other particle, no matter how far away they are from each other.
This 'alteration' is achieved by measuring the state of one of the particles. Which can be either a 0 or 1, both at the same time.
If the measurement of one particle (spin) is 0, the other particle always settles on being a 1.
This has been proven time and time again.

This fact allows one to make a super fast Quantum Computer. One that could break any encrypted code......if it started off with enough entangled particles.
I believe scientists have been able to entangle 4 quantum particles, which has allowed them to produce a super fast computer.....One which only gives the answer to simple maths problems.

Building a larger Quantum Computer with say 20 entangled Qbits, has not been possible to date.
As the difficulty is the storage of the entangled particles.

Storage methods have been Crystals, where electrons are released by a Laser.
Ion traps, storage in Electomagnetic fields.
Particle storage in superconducting materials that exihibit no resistance at very low temperatures (using Helium)

One day a Super Quantum Computer will be built.
It might use Caesium atoms, or even Radioactive particles. The right storage conditions for the right Particles have yet to be found, but eventually it will be.
Then there will have to be total freedom of every type of information, for everyone everywhere.
Since the will be no such thing as a Secret









.

.
"You will never find a real Human being - Even in a mirror." ....Mike Kremer.


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@@@ it just so happens that Entanglement, and in particular Quantum entanglement is a fact. @@@

Sorry to rain on your parade, but so called "entanglement" is a groundless and incorrect speculation. It is based on the QM Projection Postulate, which has been deprecated 70 years ago. Poor computer scientists have not heard about it yet crazy

es



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What happend to your PRL paper on this topic?

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Hi,

You have a pretty good memory.
They've said they were not interested, without going into formal review.
But later on I have written an another paper, specifically on the Projection Postulate and its history. Submitted it to the Phycics Essay. They've send it to two reviewers, who opinionated that the topic is not interesting for their readers.
So I have sent it to the Foundations of Physics.
And they responded that topic does not belong to the foundations of Physics!

That is all. I have get the idea that it does not make sense to fight the wind mills smile

ES



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