What is Quantum Key Distribution?
Both the sender and the receiver share a common secret key. This is also called Symmetric Cryptography. The Sender will encrypt the information with the secret key and the receiver will decrypt the information using the same key. Thats the idea.
So where does Quantum [Security] come in?
When the Sender and Receiver decide to communicate securely. They have to agree on the secret key for the purposes of the secure communication. This process of exchanging pre-communication information aka the secret key before the encrypted communications can occur is done using Quantum Principles.
QKD works in two modes
Over The Air — The sender and receiver communicate via a satellite in space. The Sender sends packets to it and the satellite relays it back to the Receiver. And vice versa. This happens in the air. Both the sender and receiver are on the ground (Earth’s Surface).
Over Optical Fiber Networks — The Sender and Receiver are connected together via an Optical Fiber Network. Very much like the internet optical fiber networks we use today.
How is Quantum Secure Communication different from the Normal Optical Fiber Communication?
In Normal Fiber communication, you send a lot of photons which signify 1, and if the clock ticks and there is darkness then it signifies 0. Thats basically how it works.
The way QKD works is NOT by Amplitude/Intensity of photons. But rather by transmitting The Quantum State of Photons. QKD can be overlaid with Normal Optical Fiber Communication Lines.
Can QKD be used for other Cryptographic Applications like Storage, Messaging, Digital Signatures, Transactions, Voting, Email, Chatting, Documents etc.?
Short Answer: No!!!
Long Answer: QKD is not a Full Fledged Cryptographic Framework. The only niche it enables for you is Quantum Secure Communication by solving the most important part of that, which is Secure Secret Key Exchange Using Quantum Secure Methods.
And hence by virtue of its design it CANNOT be used as a General Purpose Cryptographic Scheme. And hence cannot be applied to securing Storage, Documents, Messaging, Transactions, Voting, Email, Chatting etc.
Which can be done using Post Quantum Cryptography. For which Automatski has the worlds first commercial implementation since 2014 CE
QKD does exactly what it does, which is … it secures the transport layer of the communication channel between 2 parties.
Has QKD Been Compromised Ever? How Secure is it in Reality? Everyone says that QKD aka Quantum Security can NEVER be Compromised!
Yes! Actually Each and Every/All Known production QKD system has/have been/can be hacked/compromised using Side Channel Attacks.
We Bet Nobody Told You This Teeny Weeny Detail…
We explained to you how normal Optical Fiber Communication works vis-a-vis QKD.
We are sure everyone who is using Hyperbole and Powerpoint’s about QKD & Quantum Security didn’t tell you just one teeny weeny bit of detail.
Well, you see as Photons travel they loose intensity due to various environmental reasons, absorption etc.
So normally Photons can travel about ~100km in an optical fiber before requiring an amplifier/relay, to reamplify and retransmit the photon signals again.
This is NOT a problem in normal Optical Fiber communication because they simply work by 1’s and 0’s represented by Light and Darkness (simply stated). So basically all that an amplifier/relay has to do every ~100kms is basically detect if there is Light, then produce more Photons and pump them down the other side alongside the original photons. Simple! Thats how the internet works.
But in Quantum Computing there is a Fundamental No Cloning Theorem. Which basically stated that Quantum State “CANNOT” be copied/duplicated. If you try measuring Quantum State you cannot do that without collapsing it to 0’s and 1’s.
Which basically means that there is no way you can have amplifiers/relays in QKD Communication after every ~100kms. Because to amplify the signal they will have to measure, copy and create more of photons with the exact same quantum state as is in the original signal. Which as per proven Quantum Physics is NOT Possible.
So the best that can be done is that the relay will also actively part take in the communication. And will also store a copy of the secret key. And will decrypt all messages/photons and re-encrypt the messages/create-lots-of-new-photons and send them over the next ~100km leg before the next relay does the exact same thing.
This basically means that every ~100kms your so called Quantum Secure Encrypted Message is Available in Clear Text for anyone to read.
So what happens with Over The Air — Satellite Mediated Communications?
Well it is reasonably assumed that there wouldn’t be too many motivated people with enough money and resources who will fly into space, locate the exact satellite and bug it to send copies of clear text messages to your receivers on earth. So that you can snoop on all encrypted communication.
How does China do it? China is the world leader in QKD and has spent Billions of Dollars on Developing it.
Again we bet nobody told you this but the way China has setup QKD Optical Fiber Networks between its Military Locations is simply by having The Chinese People’s Liberation Army Battalions every ~100kms Physically Guarding and Securing The Quantum Relays 24×7.
And they also use Satellite Mediated QKD Communications between multiple locations.
So what are the QKD Vendors saying about all this?
They are claiming they are working on Top Secret Projects which will enable them to create Optical-To-Optical Quantum State Copying And Amplifying Relays.
Which are impossible as per Quantum Physics. We are not sure why everyone is NOT calling their Bluff.
So much so for Quantum Secure Communications!
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