Juan Antonio Vieira Giestinhas

arXiv2026

Information-Theoretic Solutions for Seedless QRNG Bootstrapping and Hybrid PQC-QKD Key Combination

This paper considers two challenges faced by practical quantum networks: the bootstrapping of seedless Quantum Random Number Generators (QRNGs) and the resilient combination of Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD) keys. These issues are addressed using universal hash functions as strong seeded extractors, with security foundations provided by the Quantum Leftover Hash Lemma (QLHL). First, the 'randomness loop' in QRNGs -- the requirement of an initial random seed to generate further randomness -- is resolved by proposing a bootstrapping method using raw data from two independent sources of entropy, given by seedless QRNG sources. Second, it is argued that strong seeded extractors are an alternative to XOR-based key combining that presents different characteristics. Unlike XORing, our method ensures that if the combined output and one initial key are compromised, the remaining key material retains quantifiable smooth min-entropy and remains secure in exchange of longer keys. Furthermore, the proposed method allows binding of transcript information with key material in a natural way, providing a tool to replace computationally based combiners to extend ITS security of the initial key material to the final combined output. By modeling PQC keys as having HILL (Hastad, Impagliazzo, Levin and Luby) entropy, the framework is extended to hybrid PQC-QKD systems. This unified approach provides a mathematically rigorous and future-proof mechanism for both randomness generation and secure key management against quantum adversaries.

quant-ph↗

arXiv2025

On Post-Quantum Cryptography Authentication for Quantum Key Distribution

The traditional way for a Quantum Key Distribution (QKD) user to join a quantum network is by authenticating themselves using pre-shared key material. While this approach is sufficient for small-scale networks, it becomes impractical as the network grows, due to the total quadratic increase in the number of pre-shared keys required. To address this scalability issue, Public Key Infrastructure (PKI) combined with Post-Quantum Cryptography (PQC) offers a more scalable solution, allowing users to authenticate the QKD traffic remotely to obtain information-theoretical secure (ITS) keys under the presented assumptions. Unlike traditional PKI, which relies on classical cryptographic algorithms such as RSA, the approach presented in this paper leverages PQC algorithms that are believed to be resistant to quantum attacks. Similarly to the SIGMA or TLS protocols, authentication, confidentiality, and integrity are achievable against bounded adversaries to ensure secure and scalable quantum networks.

quant-ph↗