Abstract: Methods, nodes and systems for secure symmetric key distribution are described. A method of creating symmetric keying material shared between a first node and a second node is provided. The method comprises: establishing a key-generation channel between the first node and the second node; generating shared symmetric master keying material using physical layer security methods on the key-generation channel; generating random numbers as local keying material on the first node; encrypting the local keying material using some or all of the shared symmetric master keying material to generate encrypted local keying material on the first node; sending the encrypted local keying material from the first node to the second node over a communication channel; and decrypting the encrypted local keying material on the second node using the corresponding shared symmetric master keying material to create symmetric keying material.

Abstract: A method of key distribution, a key distribution system, a single photon source system and a method of generating single photons. The method of key distribution comprises the steps of: providing a free space optics, FSO, link between a transmitter and a receiver; detecting whether an eavesdropper is present along the FSO link; transmitting individual photons or weak coherent pulses, as an approximation of individual photons, each encoding a basic unit of the key according to a binary or higher number base system from the transmitter to the receiver; and comparing timing information associated with the transmission and reception of the individual photons for determining the key when it is detected that no eavesdropper is present along the FSO link.

Abstract: A method of key distribution, a key distribution system, a single photon source system and a method of generating single photons. The method of key distribution comprises the steps of: providing a free space optics, FSO, link between a transmitter and a receiver; detecting whether an eavesdropper is present along the FSO link; transmitting individual photons or weak coherent pulses, as an approximation of individual photons, each encoding a basic unit of the key according to a binary or higher number base system from the transmitter to the receiver; and comparing timing information associated with the transmission and reception of the individual photons for determining the key when it is detected that no eavesdropper is present along the FSO link.