Abstract: A system for quantum key distribution includes a first data processing device; a second data processing device; and a transmission line extending between the first data processing device and the second data processing device. The transmission line comprises an inner optical fiber, a shielding layer surrounding the inner optical fiber, and an outer optical fiber surrounding the shielding layer. The first data processing device and the second data processing device are configured to determine a shared key by quantum key distribution via quantum signals along the inner optical fiber. The system is configured to determine outer signal losses along the outer optical fiber.

Abstract: A system and method for authenticating an optical fiber key includes selecting a plurality of at least partially randomized challenge pulse parameters, generating a first optical challenge pulse based on the plurality of at least partially randomized challenge pulse parameters, determining an optical response signal based on a reflected signal of the first optical challenge pulse from the optical fiber key, applying a comparing algorithm the optical response signal and an expected response based on previously recorded optical response signals of the optical fiber key to a reference optical challenge pulse for determining a similarity metric, and authenticating the optical fiber key based on the similarity metric.