Point to multi-point physical-layer key generation and distribution in passive optical networks

Area of Science:

• Optical communication security
• Quantum key distribution principles

Background:

• Passive Optical Networks (PONs) are widely used for broadband access.
• Existing security measures in PONs often rely on higher layers, leaving physical layer vulnerabilities.
• Need for robust, integrated physical layer security solutions in optical networks.

Purpose of the Study:

• To propose and demonstrate a physical-layer secure key generation and distribution (SKGD) scheme for PONs.
• To enhance the security of PONs by utilizing the unique properties of optical fiber links.
• To achieve high-speed, error-free key generation compatible with current infrastructure.

Main Methods:

• Implementation of a point-to-multi-point SKGD scheme in a PON.
• Broadcasting optical signals with fast fluctuating states of polarization (SOPs) from the Optical Line Terminal (OLT) to Optical Network Units (ONUs).
• Utilizing the high sensitivity of SOP dynamics to specific fiber link characteristics for security.
• Employing a Sagnac interferometer-based polarization scrambler as a high-speed random source.

Main Results:

• Demonstration of a 3.9 Gb/s SKGD over 11 km of single-mode fiber.
• Generation of highly correlated key waveforms shared between OLT and ONUs.
• Verification of generated key sequences as error-free and truly random.
• High-level security guaranteed by the sensitivity of SOP dynamics.

Conclusions:

• The proposed SKGD scheme offers a flexible and effective solution for enhancing security in PONs.
• The scheme is compatible with existing PON infrastructure, facilitating easier adoption.
• Physical-layer security using SOP dynamics presents a promising approach for future optical networks.