The rapid development of quantum computing poses severe threats to traditional blockchain security mechanisms, while existing full-quantum blockchains face challenges regarding high hardware costs and limited scalability. To address these issues, this paper proposes a secure and practical semi-quantum blockchain system. Specifically, a Semi-Quantum Delegated Proof of Stake consensus mechanism is constructed by integrating an adapted semi-quantum voting protocol with the Borda count method and a malicious behavior penalty model. Furthermore, a lightweight transaction verification framework is designed based on semi-quantum key distribution, enabling classical users with limited quantum capabilities to participate securely. Theoretical analysis demonstrates that the system achieves unconditional security against quantum attacks while maintaining high throughput. These results indicate that the proposed asymmetric resource design significantly lowers hardware barriers compared to full-quantum schemes, effectively balancing security, practicality, and cost-effectiveness for post-quantum blockchain networks.

Quantum key distribution (QKD) provides unconditional security but relies on repeaters to extend coverage, thereby introducing repeater trust risks—compromised repeaters may leak keys. Brakerski/Fan-Vercauteren scheme (BFV)-based QKD addresses this issue through key encryption and quantum attack resistance. However, Fast Fully Homomorphic Encryption over the Torus (TFHE) outperforms BFV in encryption/decryption speed for single-qubit homomorphic XOR operations, which is critical for the real-time requirements of QKD. We propose TFHE-based QKD (TQKD), a quantum key distribution protocol based on public-key TFHE. During key forwarding, it leverages the “usable-but-unobservable” property of homomorphic encryption to prevent key exposure. A reduction proof verifies the scheme’s Indistinguishability under Chosen-Plaintext Attack (IND-CPA) security. To validate TQKD’s computational speed advantage, we developed code using the Open-Source Fully Homomorphic Encryption Library (OpenFHE) platform and designed single-pass and multi-hop relay experiments. We compared the computational efficiency of TQKD against QKD schemes based on similar homomorphic encryption algorithms, Brakerski-Gentry-Vaikuntanathan scheme (BGV) and BFV. Results demonstrate that our scheme achieves faster key encryption/decryption speeds in both scenarios, significantly reducing processing time compared to similar algorithms. Furthermore, while enhancing the scalability of quantum key distribution networks, the added computational overhead is negligible, indicating higher practical value.

An implementation that passes internal round-trip tests may still produce artifacts that another library cannot consume. We present an auditable workflow for selected-vector conformance and raw-artifact interoperability testing of ML-KEM and ML-DSA in liboqs and PQMagic. The workflow links FIPS 203/204 Automated Cryptographic Validation Protocol (ACVP) projections, bidirectional producer–consumer cases, and deterministic negative tests to vector and binary hashes. For pinned liboqs 0.15.0 and PQMagic-SHAKE builds, both adapters matched all 690 expected implementation-vector outcomes across ML-KEM-512/768/1024 and ML-DSA-44/65/87. All 1200 bidirectional positive cases and 90 deliberately sparse deterministic one-bit mutation cases produced their specified outcomes. A supporting regression check passed 12 persisted-artifact replay cases between two PQMagic builds from the same commit; it does not establish cross-version compatibility. Performance measurements provide a descriptive single-session snapshot on one Windows host, with 50 timed batch observations per operation. Aigis and SHAKE/SM3 comparisons are supporting configuration analyses, not extensions of the standardized cross-library compatibility claim. The accompanying deployment considerations are a taxonomy and checklist, not a validated decision procedure. The contribution is an auditable record of specified artifact-level behavior, bounded by the selected vectors, recorded commits, host, and interfaces. It does not establish product certification, protocol interoperability, or stable performance rankings across sessions.

Quantum Key Distribution (QKD) ensures secure key establishment through the principles of quantum mechanics; however, its effectiveness in practice hinges on dependable identity verification via classical channels during the post-processing phase. Current QKD implementations typically depend on pre-existing symmetric-key authentication, which suffers from limited scalability and complicated key management in extensive networks. Authentication methods utilizing post-quantum cryptography (PQC) signatures, based on complex mathematical assumptions, introduce extra and uncertain security dependencies, potentially compromising the security model integrity that QKD aims to maintain. This paper explores the application of hash-based signatures (HBS) for identity verification in the post-processing of QKD. HBS methods derive their security from cryptographic hash functions, which are integral to QKD protocols, allowing for scalable public-key-style authentication without the need for new computational assumptions. A detailed authentication framework is proposed, incorporating HBS-based verification into all essential phases of QKD post-processing, such as mutual certificate validation, basis sifting, parameter estimation, error correction verification, and privacy amplification. Security assessments indicate that the suggested framework maintains the security model integrity of QKD by relying cryptographically solely on the collision resistance of hash functions—without introducing new computational assumptions. At the system deployment level, it adheres to standard PKI trust assumptions which are necessary for public-key-style authentication and consistent with practical QKD network operations. Additionally, system-level evaluations affirm the scalability and practical applicability of HBS-based authentication, while also addressing the operational trade-offs among various HBS approaches in realistic QKD deployment contexts.