BB84

The BB84 protocol, named after its inventors Charles Bennett and Gilles Brassard in 1984, is a prepare-and-measure Quantum key distribution (QKD) protocol, in which, one party (e.g. Alice) performs the encoding by preparing the quantum states, and the other party (e.g., Bob) measures them. The BB84 QKD scheme is the first quantum cryptography protocol, and has become one of the most well-studied QKD protocols. The protocol is provably secure assuming a perfect implementation, relying on two conditions: (1) the quantum property that information gain is only possible at the expense of disturbing