Quantum Cryptography or Quantum Key Distribution (QKD) is a new technique that uses principle of quantum mechanics to generate the shared, secret key between sender and receiver (most commonly known as Alice and Bob). With the help of QKD, it is now possible to construct cryptographic system which can detect unauthorized eavesdropping and gives guarantee of safe communication.
Quantum Cryptography is based on the use of subatomic particles (photons) and their intrinsic quantum properties (photon polarization) to develop an unbreakable system. It is not possible to measure the quantum state of any system without affecting the system. This property provides secure transmission of key between sender and receiver. Quantum Cryptography is a way to combine the relative ease and convenience of key exchange in public key cryptography with the ultimate security of a one-time pad.
BB84 is the first Quantum cryptography protocol. It is most widely used for quantum key distribution, which allows two users to establish an identical and purely random sequence of bits at two different locations while allowing revealing any eavesdropping
Source: Montclair State University
Author: Shubhra Mittal