Bennett-Brassard protocol (BB84)

The Bennett-Brassard protocol (BB84) is a method for secure communication using quantum physics. It involves sending bits of information encoded as tiny particles of light (photons) in different polarizations. The sender (Alice) randomly chooses two bases to encode each bit, and the receiver (Bob) measures in random bases. Because of quantum principles, any eavesdropper trying to intercept the communication disturbs the photons, revealing their presence. Afterward, Alice and Bob compare a subset of their measurements over a classical channel to detect any interception. If no eavesdropper is detected, they can securely generate a shared encryption key.