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International Conference on Sensors and Information Technology (ICSI)

Finite Size of Gaussian-Modulated Continuous-Variable Quantum Key Distribution with an Untrusted Entanglement Source

Yourui Yang

Published Mar 21, 2025• 0 citations
Publisher

Abstract

The Gaussian-modulated continuous-variable quantum key distribution (GMCVQKD) scheme based on untrusted entanglement sources simulates scenarios where the source may be controlled by an attacker. However, Existing analyses often assume ideal settings and overlook finite-size effects. This paper addresses these gaps by evaluating the GMCVQKD scheme under specific attack scenarios, considering limited signal exchanges between Alice and Bob. We examine the secret key rate under finite-size conditions, analyzing factors such as the positioning of the entanglement source and the effectiveness of the reconciliation process., and compares results to the asymptotic regime. The findings reveal a decline in key rate under finite-size effects, highlighting the influence of statistical fluctuations. This work advances practical CVQKD implementation and offers theoretical guidance for system deployment.

DOI
10.1109/icsi64877.2025.11009996

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We perform security analysis of a passive continuous-variable quantum key distribution (CV-QKD) protocol by considering the finite-size effect. In the passive CV-QKD scheme, Alice utilizes thermal sources to passively make preparation of quantum state without Gaussian modulations. With this technique, the quantum states can be prepared precisely to match the high transmission rate. Here, both asymptotic regime and finite-size regime are considered to make a comparison. In the finite-size scenario, we illustrate the passive CV-QKD protocol against collective attacks. Simulation results show that the performance of passive CV-QKD protocol in the finite-size case is more pessimistic than that achieved in the asymptotic case, which indicates that the finite-size effect has a great influence on the performance of the single-mode passive CV-QKD protocol. However, we can still obtain a reasonable performance in the finite-size regime by enhancing the average photon number of the thermal state.