In an aspect, the present invention provides an optical encryption terminal for generating and distributing a cryptographic key signal in a cryptography key distribution system having at least two optical encryption terminals. The optical encryption terminal comprises an electronic processing unit and the optical encryption terminal is configured to selectively receive optical input signals generated by a source of electromagnetic radiation and optical input signals generated by a further optical encryption terminal, and to selectively output first optical output signals to a detection element and second optical output signals to the further optical encryption terminal, wherein the first optical output signals are based on the optical input signals generated by the further optical encryption terminal and transformed in accordance with an optical encryption pattern provided at the optical encryption terminal. Furthermore, the optical encryption terminal is configured to determine, using the electronic processing unit, a cryptographic key signal on the basis of at least one radiometric and/or photometric quantity associated with the optical output signals detected by the detection element.