Noise-limited secret key agreement with twin optical physically unclonable functions
2026-07-06 • Cryptography and Security
Cryptography and Security
AI summaryⓘ
The authors study a way to use twin optical fingerprints, which are unique light patterns created by special optical components, to generate and share secret cryptographic keys. They develop a method that lets two users create a common secret key even when there is noise or small differences in the devices. Their approach includes steps to correct errors and protect privacy, and they also measure how much information might leak during the process. Finally, they explore how these twin optical fingerprints could help start secure communication in quantum key distribution systems without needing trusted third parties.
Physical Unclonable Function (PUF)Optical fingerprintSpeckle patternCryptographic key generationKey agreement protocolError reconciliationPrivacy amplificationInformation-theoretic securityQuantum key distribution (QKD)Secure sketches
Authors
Georgios M. Nikolopoulos
Abstract
We investigate the use of twin optical fingerprints derived from correlated physical unclonable functions (PUFs), as a hardware-based platform for cryptographic key generation and distribution. Each fingerprint is associated with a random, yet reproducible speckle pattern, generated when coherent light is scattered by a disordered optical structure. We consider a pair of correlated optical PUFs, and study the conditions under which two honest parties can establish a common secret key, despite fabrication-induced variability and environmental noise. An explicit information-theoretic key-agreement protocol is developed, incorporating secure sketches, error reconciliation, and privacy amplification. We quantify information leakage due to public helper data, and derive lower bounds on the length of the final secret key. The analysis identifies the noise regimes in which secure key agreement is feasible, and examines the performance of both practical and near-capacity reconciliation schemes. Finally, we discuss how twin optical PUFs could be integrated into quantum key distribution (QKD) networks, as a mechanism for establishing an initial pre-shared secret key between two honest users, without relying on computational assumptions or trusted third parties.