Quantum Key Distribution and BB84 Protocol

Quantum Key Distribution:

Quantum Key Distribution enables the sharing of cryptographic keys such as a private key between two or more parties so that they can securely share information such as a private key. The key can then be used to encrypt messages that are being communicated over an insecure channel. The distribution of keys is a major weakness of private key cryptography.

BB84 Protocol:

Bennet and Brassard inspired by Wiesner’s scheme, proposed a quantum key distribution (QKD) protocol, this protocol is known as BB84. This allows a sender (Alice) to send photons to a receiver (Bob). Alice and Bob communicate via a one-way quantum channel and a two-way public channel. Alice has a source of single photons and two polarizing filters – One rectilinear and one diagonal. The quantum channel, however, is vulnerable to any possible manipulation from an eavesdropper. Alice and Bob must ensure that the eavesdropper usually called Eve. It can’t tap on the quantum channel and listen to the exchanges over the classical channel.