Quantum Secure Key Exchange with Position-based Credentials

2025-06-04

AI Summary

Quantum key distribution (QKD) protocols conventionally rely on pre-shared keys or public-key infrastructure for message authentication, introducing classical cryptographic assumptions that undermine information-theoretic security. Method: This work proposes a fully post-quantum-authenticated QKD protocol that eliminates all classical cryptographic assumptions by tightly integrating delayed authentication with a simplified quantum position verification (QPV) scheme. It is the first QKD protocol authenticated via QPV, requiring only BB84 state preparation while supporting multi-basis QPV. Contributions: We refine the QPV security analysis framework by tightening trace-distance bounds via semidefinite programming (SDP), significantly improving bound tightness; reduce the number of QPV rounds substantially to enhance practicality; and achieve composable, information-theoretic security against realistic adversaries—including bounded-storage and no-cloning adversaries—without trusted infrastructure. The protocol establishes a new paradigm for trustless, quantum-secure communication.

Technology Category

• Machine Learning: Quantum Machine Learning
• Search and Optimization: Distributed Search
• Computer Vision: Adversarial Attacks & Robustness

Application Category

• Security and Privacy: Large-scale security measurements
• Web Mining and Content Analysis: Web data provenance, reliability, and authenticity
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

Quantum key distribution (QKD) provides an information-theoretic way of securely exchanging secret keys, and typically relies on pre-shared keys or public keys for message authentication. To lift the requirement of pre-shared or public keys, Buhrman et. al. [SIAM J. Comput. 43, 150 (2014)] proposed utilizing the location of a party as a credential. Here, we extend upon the proposal, develop a QKD protocol with location credentials using quantum position verification (QPV) based message and identity authentication. By using QKD with delayed authentication as a base, and later simplifying QPV-based message authentication, we significantly reduce the number of QPV runs, which currently acts as a bottleneck. Besides demonstrating security for the proposed protocol, we also provide improvements to QPV security analysis, including generalization of the QPV adversary model, tightening a trace distance bound using semidefinite programming, and propose a multi-basis QPV requiring only BB84 state preparation but with multiple measurement basis.

Problem

• Develops QKD protocol using quantum position verification for authentication
• Reduces QPV runs to overcome current bottleneck in authentication
• Improves QPV security analysis with generalized adversary model and tighter bounds

Innovation

• QKD with location credentials using QPV
• Reduced QPV runs via delayed authentication
• Multi-basis QPV with BB84 state preparation