As we are on the verge of the quantum computer era, the coming years will be inclined more towards the modernising and optimisation of various technologies. However, this will bring more challenges and threats especially in the fields of data encryption and numerous encryption algorithms which are highly used in various ecommerce platforms and Virtual Private Networks (VPN) today.
THE REAL PROBLEM STATEMENT :
Traditional computers may take hundreds or thousands of years to solve and break complex mathematical algorithms and equations, which quantum computers can address in a few hours or minutes. These computers can be used by hackers who apply numerous attacks to break encryption algorithms widely used today.
This will make cybersecurity and data encryption vulnerable to the outside world. Some of the public key cryptography algorithms like RSA,ECC encryption will be broken in a few hours, and it will be a high threat to the private data of the individual. Also,Transport Layer Security (TLS) and VPNs, could be cracked and exposed by a hacker equipped with a large enough quantum computer using Shor’s algorithm.
Shor’s algorithm is a powerful algorithm with exponential speed over classical algorithms. Consider, we are doing transactions on any ecommerce site, our credit/debit card information is stored in the enterprise’s site in the form of encrypted data via an encryption key.
HOW ENCRYPTION WORKS :
Encryption is a process in which any message or file is scrambled into any unreadable format, also called cipher text. This process helps in the security of data in the process of transmission. When the required recipient gets the file, then the message can be decrypted into a readable form by means of a secret encryption key. A secret encryption key is nothing but a collection of algorithms used to scramble and unscramble the data.
So, we have following important components in the process of encryption:

ENCRYPTION KEY

THE EXCHANGE

ENCRYPTION ALGORITHM
How can Quantum computing make encryption vulnerable:
ENCRYPTION KEY is basically thought of as a pseudo random number generator, which generates almost random numbers at every stint. But, monitoring a process of generating these random numbers over a few years time can be enough for quantum computers to predict the behaviour and break the algorithm behind this and thereby making the process vulnerable. The problem with this solution is with quantum physics. Quantum Random Number Generation (QRNG) generates random numbers with a high source of entropy using unique properties of quantum physics.
THE EXCHANGE is basically the medium or channel through which encryption key is transmitted from a sender to the intended receiver. Without the encryption key, the data would be nothing but a scrambled set of numbers which is of no use to hackers. So, exploring the exchange would help hackers to get the encryption key. This is the most vulnerable channel of data encryption. So here, by exploiting our classical algorithms through quantum computers, anybody can take control over the encryption key. To avoid this, the actual use of quantum cryptography helps in the safe transmission of encryption keys.
ENCRYPTION ALGORITHM involves various security threats posed by quantum computers. Although it’s true the RSA and ECDH algorithms are vulnerable to Shor’s algorithm on a suitable quantum computer, various researchers are working to develop replacement algorithms that will be safe from quantum computers as part of its postquantum cryptography (PQC) efforts.
HOW QUANTUM CRYPTOGRAPHY WORKS :
Quantum cryptography, or quantum key distribution (QKD), uses a series of photons (light particles) to transmit data from one location to another over a fiber optic cable. By comparing measurements of the properties of a fraction of these photons, the two endpoints can determine what the key is and if it is safe to use.
If the photon is read or copied in any way by an eavesdropper, the photon’s state will change. The change will be detected by the endpoints. In other words, this means you cannot read the photon and forward it on or make a copy of it without being detected
Detailed mechanism of quantum cryptography:

The sender transmits photons through a filter (or polarizer) which randomly gives them one of four possible polarizations and bit designations: Vertical (One bit), Horizontal (Zero bit), 45 degree right (One bit), or 45 degree left (Zero bit).

The photons travel to a receiver, which uses two beam splitters (horizontal/vertical and diagonal) to “read” the polarization of each photon. The receiver does not know which beam splitter to use for each photon and must guess which one to use.

Once the stream of photons has been sent, the receiver tells the sender which beam splitter was used for each of the photons in the sequence they were sent, and the sender compares that information with the sequence of polarizers used to send the key. The photons that were read using the wrong beam splitter are discarded, and the resulting sequence of bits becomes the key.
Therefore, there are two ways to be ready for quantum computer threats:

Quantum Cryptography which uses quantum physics to ensure safe transmission of encryption keys.

Development of strong algorithms which can nullify the effect of quantum computers which comes under postquantum cryptography methods
CONCLUSION
The combination of quantum mechanics and classical cryptography when compared with traditional computing techniques, provides higher optimisation and unconditional security. These characteristics can solve cyberspace security and numerous critical problems for the future Internet.
REFERENCES :
 Photo Sources :

https://www.qmunity.tech/post/quantumcryptographyexplained

https://www.ssl2buy.com/wiki/whatisencryptionanddecryption
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