Quantum network security

This talk gives a brief overview of how to use basic concepts of quantum mechanics to achieve unconditional network security. Quantum key distribution (QKD) is used for this purpose to enhance Vernam ciphers. A protocol used for QKD is the Bennett-Brassard (BB84) protocol, which uses 4 nonorthogonal quantum states. Ideally, it uses single photon generators and a quantum channel assisted by a classical channel to achieve secure key generation. Sometimes, for ease of implementation, weak coherent laser pulses are used instead of single photons. In this case, the protocol is vulnerable to photon number splitting (PNS) attack. In order to counter this attack, decoy state method could be used. A brief outline will be given for this approach. Other types of QKD use entangled photon states, and an example for such protocols will be briefly outlined. QKD has reached the commercial stage, and a number of companies that have available products and solutions will be listed.