abstract
Quantum cryptography is a cryptographic technology first proposed by Stephen Wiesner in the early 1970s. The technology applies phenomena of quantum physics to secure network communications of two parties. This technology then was developed for distributing symmetric keys using a BB84 algorithm, called quantum key distribution (QKD). Two parties can produce a shared random secret key used to encrypt and decrypt data between them. The primary advantage of QKD is that it can detect eavesdropping using the laws of quantum mechanics. Therefore, QKD guarantees secure key distribution. Nevertheless, practical QKD implementations are vulnerable to imperfect assumptions and have been proved that they could be eavesdropped or attacked by hackers. However, there is a new research using the three-stage quantum cryptography protocol to make the QKD implementations more secure.