In the field of cryptography, there are various algorithms used to secure the data and key plays an important role. There are two keys one is public that are available to everyone and one is a private key only available to the person whose public key is signed digitally for transferring the data or information.
But in the quantum computer there is also one key that plays a major role in data security it is Quantum key distribution. So let’s understand what is QKD, the workings of QKD, and its real-world applications.
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Introduction and basic overview of Quantum key distribution
QKD is a cryptography method with the help of quantum mechanics which later used to establish secured communication between any two entities. The quantum key distribution key is used for encryption as well as decryption in communication or messages. It ensures the confidentiality of the message and verifies that only the receiver can read the message sent by the sender.
Let’s understand the working of the key by example
To keep it simple, Alice is called the sender and Bob is called the receiver. At the start of the process, Alice prepares a pair of particles a and b. Particle c, which contains private information that needs to be transferred, is then subjected to a joint measurement, known as a bell measurement, by Alice with particles a and c in order to obtain the result that needs to be transmitted.
Due to the change in the state of a particle, the technique is also known as the no-cloning principle of quantum mechanics. After receiving the outcome from Alice through the traditional protocol, Bob applies a unitary transformation to retrieve the result and state of particle a along with the associated information.
In the above figure, the quantum mechanics concept of particle entanglement is used where any two particles are connected where distance between them are unknown. This mechanism and exchange of information is called the Quantum distribution key (QKD) and it provides secure communication between two entities.
Superposition in quantum mechanics is an important concept where every quantum state represents itself as a sum of two or more distinct states.
The addition of vectors can place a single qubit in a superposition of two states. A qubit holds quantum information in a superposition. This combination of all conceivable configurations of the qubit is referred to as this. “Entities in superposition can create complex, multidimensional computational spaces.” Particles can be in both states simultaneously, representing 0 and 1.
In the above figure, particle means photon so the sender Alice sends multiple series of photons in different states to the receiver Bob with the help of one dedicated quantum channel.
When Bob measures the photons he communicates with Alice using classical channels. After communication, both will share the secret code, and they will compare the measurement. If that is the match on both sides the key is considered valid and secured. If there is a mismatch during measurement comparison the key is attacked by a third person, and it is considered a compromised key, and the key is not considered valid and no longer usable.
Step generation in Quantum key distribution (QKD)
QKD includes various steps after completion of these steps a secure channel for communication is established.
Generation Alice and Bob sender and receiver respectively create and share their keys through entanglement and encoding.
Transmission: Alice sends the encrypted key to Bob with the help of a quantum channel.
Measurement: on receiving the key from Alice, Bob calculates the distance and details of particles.
Verification: After sharing the key Alice and Bob perform multiple tests to ensure the security of the shared key.
Security of QKD
QKD also checks for additional security measures to check for valid keys. For that, Alice and Bob can use error checking and correction algorithms that are available in the cryptography for checking of errors during the communication. QKD also uses quantum repeaters to improve the strength in long-distance communication and regenerates the signal if it is unreachable or breaks in midway.
Applications of QKD
The quantum key distribution provides one secure channel for communication that is resistant to cyber-attacks. Some industry use cases are listed below.
Secured transaction: QKD provides secure and reliable communication channels for payments and financial transactions that can not be hacked easily.
Government Sector: An institute like a government agency can use QKD for communication and transferring of important files and sensitive data to protect from other people who are not authorized to access that information.
Medical sector: Using QKD health-related data and patient information can be secured.
Internet of Things: Generally communication over IoT devices is prone to cyberattacks as channels are vulnerable to attack so with the help of QKD it can be secured.
Cryptography: QKD can improve the existing cryptography methods by integrating quantum mechanism techniques for secure communication in the future.