Quantum Encryption:Exploiting quantum physics.

Quantum Encryption

New ways of protecting our information have become necessary with the recent boom in cyber hacking, but what if instead of using fancy (and computationally intensive) algorithms, we could use the laws of physics to send messages securely? Quantum cryptography is just one way of eliminating the issue of “eavesdroppers”, Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best known example of quantum cryptography is quantum key distribution which offers an information-theoretically secure solution to the key exchange problem.

One popular encryption scheme, for instance, can be undone only by factoring a huge random number, a “key” unlocking encoded information, into two prime numbers. It’s a task that today is extraordinarily difficult, but not impossible. With enough computing power, a spying government could break the key.

IN the history of cryptography, quantum cryptography is a new and important chapter. It is a recent technique that can be used to ensure the confidentiality of information transmitted between two parties. quantum key distribution guarantees long-term secrecy of confidential data transmission. Long-term secrets encrypted today using classical ciphers could very well become illegitimately decryptable in the next decades. Quantum cryptography draws its strength from the weirdness of reality at small scales. The particles making up our universe are inherently uncertain creatures, able to simultaneously exist in more than one place or more than one state of being. They choose how to behave only when they bump into something else or when we measure their properties.

What is cryptography?-
Cryptography is the study and implementation of sending information securely between parties in the presence of unwanted listeners complex and more applicable to modern world products. The use of cryptography can be found in a range of products including bank cards, digital passwords, ultra-secure voting and power grids. But with these advancements comes smarter ways to hijack and decrypt these messages.


Quantum cryptography was proposed first by Stephen Wiesner, then at Columbia University in New York, who, in the early 1970s, introduced the concept of quantum conjugate coding. Quantum cryptography uses Heisenberg’s uncertainty principle, formulated in 1927, and the No-cloning theorem.first articulated by Wootters and Zurek and Dieks in 1982.
The No-cloning theorem demonstrates that it is impossible to create a copy of an arbitrary unknown quantum state. This makes unobserved eavesdropping impossible because it will be quickly detected, thus greatly improving assurance that the communicated data remains private. Random rotations of the polarization by both parties (usually called Alice and Bob) have been proposed in Kak’s three-stage quantum cryptography protocol. In principle, this method can be used for continuous, unbreakable encryption of data if single photons are used. The basic polarization rotation scheme has been implemented.

Modern-day physics behind Quantum Crpytion

We start with two parties: Alice and Bob. Alice wants to send Bob some information securely, such as establishing a “private key,” and does it via quantum cryptography.
●First, she gets a very low intensity laser capable of firing photons out individually. She then polarizes each photon in a specific way, For simplicity, Alice only uses 4 filters to polarize this light: vertical, horizontal, left diagonal and right diagonal.

●Now Bob on the other hand only has two filters: vertical-horizontal (plus sign) and left-right diagonal (cross sign), positioned in a detector ready to capture these photons.
They establish what each of the four polarizations correspond to in binary code:
•Vertical, left diagonal = 0
•Horizontal, right diagonal = 1

Steps followed.
Working of Alice and Bob description.

Now, as Bob receives each photon (step 2), he tells Alice which filter he uses. If the filter matches the polarization that Alice had set, she replies with “yes”. If it doesn’t, she replies with “no”. This is done for several photons until a sufficient number of photons have been accepted to constitute a “private key”.
Now if an eavesdropper came in and tried to intercept the message before it gets to Bob, Alice and Bob will notice a change in the polarization of the photons, alerting them to the eavesdropper. They will then know that the line is not secure, and to dump the current “private key”.



Along with QKD, quantum cryptography has a number of applications, including:
• Position-based quantum cryptography: instead of using a “private key”, a person must be in a specific location in order to receive the message.
Device-independent quantum cryptography: a protocol looking into a device’s security regardless of the quantum device’s truthfulness.

Post-quantum cryptography: refers to cryptographic algorithms (usually public-key algorithms) that are thought to be secure against an attack by a quantum computer.


Unfortunately, quantum cryptography does have its limitations. Although the theory is valid, scientists have yet to come up with perfect equipment for detecting these photons for a reasonable price. Not to mention, quantum systems aren’t perfect – whether it be human error or getting the photons to behave the way we want them to. This method still has a long way to go but provides a more secure method for sending and receiving confidential material.

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