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Introduction to Quantum Cryptography

 

One of the great potential applications of quantum mechanics is quantum cryptography. According to physicists, quantum cryptography is a safer method for transmitting the desired information, as it uses the logic of quantum mechanics, unlike classical cryptography.

What matters in quantum cryptography is quantum keying. For this, basically, two quantum algorithms or protocols have been created.

The first of these is the BB84 protocol, which is still used today. This method was developed by Charles Bennett and Gilles Brassard in 1984.

This protocol takes advantage of the polarization states of photons. Let's start to explain the protocol through familiar names.

Let Alice want to send the requested information, for example, 11010011, to the recipient Bob. Let Eve, our third character, be the person who captures the quantum information Alice sent before it reaches Bob.

Alice will transmit 11010011 information, which is made up of photons, to Bob via fiber optic cables. | Let the and / filters be used to measure the 0 qubit, and the - and \ filters to measure the 1 qubit.

Let Bob measure the disposable quantum information that reaches Bob without being subjected to any espionage situation, using the filters in his hand, and the information he obtained is 11010110. As you can see, the information that Bob reaches is different from half of the information that Alice wants to send. The main reason for this is that Bob and Alice do not inform each other about their filters beforehand. Therefore, if Alice and Bob use the quantum switching filters they have previously agreed upon, the information will be delivered to the receiver correctly.

However, there is a risk here. Eve, which we define as a third character, may be able to hack information. However, Eve must be able to find the correct measuring filter. In this way, he can reach half-true or half-false information. If encryption is done by squaring the key decided by Alice and Bob, the security of the system increases even more. Thus, quantum cryptography is provided.

The second quantum cryptography method is the EPRBE protocol. This method is created by exploiting the quantum uncertainty and entanglement state. This protocol is somewhat complex in nature and therefore difficult to implement up to date.

Generally speaking, quantum cryptography is a subject that has been studied a lot by scientists. Because of the use of classical cryptology electronic circuit devices, they are more robust. However, creating a quantum state between photons and transmitting the generated photons without loss is a disadvantage. Because, due to any external factor such as temperature and interference, quantum states can be disrupted immediately. For all these reasons, quantum cryptographic optimizations are being made for military studies, although it seems difficult to adapt them to daily life for now.

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