Encryption is a very important part of cyber security. It ensures that data is only viewed by intended users. According to Rouse (2014), Encryption is a process by which plaintext or plain data is transformed from readable form to encoded form that cannot be read or decrypted by any entity without a decryption key. Encryption is important because it ensures that data cannot be viewed even after it falls on the wrong hands.

Data stored in the database and files or data being transmitted over a network ought to be encrypted to secure it from access by intruders, cyber criminals and/or hackers. Since encrypted data uses decryption key, transferring the key becomes a challenge because if the data and the key lands in the wrong hands, the data can be decrypted and viewed. There are many ways to protect data and preserve both data confidentiality and integrity. Some of the encryption measures include: symmetric cryptography, one-time pad and quantum key distribution. This paper will discuss the Quantum key distribution concept, mechanisms involved, classification and future trends.

Quantum Key Distribution (QKD)

Quantum Key Distribution (QKD), although often wrongly termed as quantum transmission, is a secure communication approach that uses cryptographic protocol made up of quantum mechanics components (Ouellette, 2004). Unlike other encryption measures, QKD is only used between communicating parties to randomly generate and transmit a secret key used to either encrypt or decrypt data and/or information transmitted over the network (Lütkenhaus, 2014).

Basic Mechanism of QKD

The main reason as to why QKD has a promising future implementation is because it is based on the basics of quantum mechanics which measures the system, hence, the possibility to detect eavesdropper or intrusion. Additionally, intruders leave fingerprints which will alert the legitimate parties exchanging the information. Intrusion errors and leaks are fixed through error correction measures and privacy amplification steps that ensures the private key is only known to the communicating parties (Bos, Costello, Naehrig & Stebila, 2015).

According to Martin, Martinez‐Mateo, and Peev (2016), QDK requires a quantum channel or a fiber to send different quantum states of lights between the sender and receiver. The channel, although it is not necessarily secure, must be authenticated so as to allow post-processing steps to be conducted. Finally, a key exchanging protocol that is based on quantum mechanics is required.

Classification of QKD

There are different approaches of QKD. The first one is the Discrete Variable QKD, which converts or encrypts quantum information to discrete variables which are measured with single photon detectors on the receiving end so as to determine their quantum states (Xu, Curty, Qi, Qian & Lo, 2015). An example of different approaches of QDK is the E912 protocol. Continuous-variable QKD (CV-QDK) is the second approach used. CV-QDK encrypts quantum information onto amplitude and phase quadrature of a coherent laser, which can be measured using homodyne detectors on the receiving end. (Diamanti, & Leverrier, 2015). Both approaches have theoretically been proven to be secure even when there is an intruder.

Future Trends

Although invention and concepts of QKD begun in the 1980’s, there is still a promising future for these mechanisms. As technology progresses, existing encryption measures become weak because of high processing power of computers which can be used to crack them. Although research on development of quantum computers is still continuing, it is theorized that the existing encryption measures will be vulnerable to the processing power of quantum computers and systems, hence the need to develop encryption measures that will be strong enough for quantum systems. The fact that different companies are working on developing quantum systems, security experts should also work hard to develop security systems that will withstand either future high processing computer systems or quantum-based computers.


Bos, J. W., Costello, C., Naehrig, M., & Stebila, D. (2015, May). Post-quantum key exchange for the TLS protocol from the ring learning with errors problem. In Security and Privacy (SP), 2015 IEEE Symposium on (p. 553-570). IEEE.

Diamanti, E., & Leverrier, A. (2015). Distributing secret keys with quantum continuous variables: principle, security and implementations. Entropy17(9), 6072-6092.

Lütkenhaus, N. (2014). Quantum key distribution. In Quantum Information and Coherence (p. 107-146). Springer, Cham.

Martin, V., Martinez‐Mateo, J., & Peev, M. (2016). Introduction to Quantum Key Distribution. Wiley Encyclopedia of Electrical and Electronics Engineering.

Ouellette, J. (2004). Quantum key distribution. Industrial Physicist10(6), 22-25.

Rouse, M. (2014). Encryption. Retrieved from https://searchsecurity.techtarget.com/definition/encryption.

Xu, F., Curty, M., Qi, B., Qian, L., & Lo, H. K. (2015). Discrete and continuous variables for measurement-device-independent quantum cryptography. Nature Photonics9(12), 772.