A communications system and method includes first circuitry for receiving plurality of data streams and processing the plurality of data streams to associate with each of the plurality of data streams a orthogonal function to cause each of the plurality of composite data streams to be mutually orthogonal to each other on a link to enable transmission of each of the plurality of data streams on the link at a same time. Quantum key processing circuitry generates a secret key for transmission to second circuitry using a quantum key generation process and for encoding the plurality of data streams for transmission on the link using the generated secret key. Third circuitry transmits the encoded plurality of data streams on the link.