Optimization of intensity-modulation/direct-detection optical key distribution under passive eavesdropping

Abstract

We analyze theoretically optimal operation of an optical key distribution (OKD) link based on fine intensity modulation of an optical signal transmitted over an attenuating channel to a direct detection receiver. With suitable digital postprocessing, the users may generate a secret key that will be unknown to an unauthorized party collecting passively a fraction of the signal that escapes detection by the legitimate recipient. The security is ensured by the presence of the shot noise that inevitably accompanies eavesdropper's attempt to detect the collected signal. It is shown that the key amount depends on a ratio that compares legitimate recipient's and eavesdropper's capabilities to detect the signal, including noise contributed by their respective detectors. A simple proportionality relation is derived in the strong eavesdropping regime and closed expressions for the optimal depth of binary intensity modulation as well as the discrimination thresholds for hard-decoded direct detection are given. The presented results substantially simplify design of practical OKD systems operating under changing external conditions, e.g. variable atmospheric absorption in the case of free-space optical links.

arXiv comment13 pages, 4 figures, 1 table

References in corpus (19)

• The Security of Practical Quantum Key Distribution
• Advances in Quantum Cryptography
• Secure quantum key distribution with realistic devices
• Quantum key distribution using gaussian-modulated coherent states
• Continuous Variable Quantum Cryptography - beating the 3 dB loss limit
• Continuous-Variable Quantum Key Distribution with Gaussian Modulation -- The Theory of Practical Implementations
• Long Distance Continuous-Variable Quantum Key Distribution with a Gaussian Modulation
• Virtual Entanglement and Reconciliation Protocols for Quantum Cryptography with Continuous Variables
• Squeezed-state quantum key distribution upon imperfect reconciliation
• Quantum Limits in Optical Communications
• Long-distance continuous-variable measurement-device-independent quantum key distribution with discrete modulation
• Numerical Study on Secrecy Capacity and Code Length Dependence of the Performances in Optical Wiretap Channels
• Continuous-variable quantum key distribution with a leakage from state preparation
• Preventing side-channel effects in continuous-variable quantum key distribution
• Secret key distillation across a quantum wiretap channel under restricted eavesdropping
• Quantum Keyless Privacy vs. Quantum Key Distribution for Space Links
• Hacking Alice's box in CV-QKD
• Secret key distillation over satellite-to-satellite free-space optics channel with a limited-sized aperture eavesdropper in the same plane of the legitimate receiver
• Low-cost limit of classical communication with restricted quantum measurements

Cited by in corpus (9)

• Optimizing state-discrimination receivers for continuous-variable quantum key distribution over a wiretap channel
• Probabilistic amplitude shaping for continuous-variable quantum key distribution with discrete modulation over a wiretap channel
• Quantum Pulse Gate Attack on IM/DD Optical Key Distribution Exploiting Symbol Shape Distortion
• Continuous-variable quantum key distribution over multispan links employing phase-insensitive and phase-sensitive amplifiers
• Employing weak-field homodyne detection for quantum communications
• Modeling Optical Key Distribution over a Satellite-to-Ground Link Under Weak Atmospheric Turbulence
• Quantum communications in continuous variable systems
• Simultaneous IM/DD Data Transmission and High-Rate Secret Key Distribution over a Single C-band Channel
• Optical downlink modeling for low-earth-orbit and medium-earth-orbit satellites under atmospheric turbulence with a quantum-state-tomography use case