Continuous Variable Quantum Distance Bounding

Quantum distance bounding (QDB) protocols verify the physical distance between communicating parties, crucial for secure authentication. Existing QDB protocols use discrete variable (DV) quantum technologies, which require specialized equipment and face scalability challenges. In contrast, continuous variable (CV) techniques in quantum key distribution (QKD) have demonstrated practicality and compatibility with existing telecommunications infrastructure.We introduce a CV QDB protocol that uses entangled EPR states and simple operations by the prover based on a shared secret for secure and precise distance measurements. By utilizing CV, our protocol benefits from quadrature measurements, enhancing practicality in real-world implementations.This work represents the first exploration of CV techniques in QDB protocols, offering a feasible and robust alternative to DV methods. Our CV QDB protocol aligns with advancements in CV QKD, overcoming limitations associated with DV approaches and paving the way for practical implementations of QDB in secure communication systems.