ABSTRACT A blockchain‐assisted quantum secret sharing (QSS) framework, denoted BQSS, is presented for function‐level dealer reduction. BQSS decomposes the conventional dealer/coordinator role into plaintext‐input, quantum‐resource, and classical‐coordination functions, and transfers the objectively verifiable coordination functions to a smart‐contract state machine. Candidate GHZ states are distributed off‐chain and sampled through stabilizer predicates; retained generation outcomes provide private mask components for a classical VSS sharing of the masked secret . The smart contract coordinates registration, active‐set freezing, commitments, deadlines, VSS evidence, reconstruction triggering, deposits, and mask openings, thereby producing a globally auditable transcript for the classical workflow. Security is analyzed under explicit system assumptions on blockchain execution, classical cryptographic soundness, measurement‐report authenticity, and dealer‐side masking correctness. The baseline instantiation adopts a public‐audit reconstruction mode for threshold‐authorized disclosure, with participant‐private opening treated as an extension. Performance is evaluated through an Ethereum‐style BN254/Groth16 on‐chain cost model and an analytical depolarizing‐plus‐loss quantum‐resource model.
ABSTRACT A blockchain‐assisted quantum secret sharing (QSS) framework, denoted BQSS, is presented for function‐level dealer reduction. BQSS decomposes the conventional dealer/coordinator role into plaintext‐input, quantum‐resource, and classical‐coordination functions, and transfers the objectively verifiable coordination functions to a smart‐contract state machine. Candidate GHZ states are distributed off‐chain and sampled through stabilizer predicates; retained generation outcomes provide private mask components for a classical VSS sharing of the masked secret . The smart contract coordinates registration, active‐set freezing, commitments, deadlines, VSS evidence, reconstruction triggering, deposits, and mask openings, thereby producing a globally auditable transcript for the classical workflow. Security is analyzed under explicit system assumptions on blockchain execution, classical cryptographic soundness, measurement‐report authenticity, and dealer‐side masking correctness. The baseline instantiation adopts a public‐audit reconstruction mode for threshold‐authorized disclosure, with participant‐private opening treated as an extension. Performance is evaluated through an Ethereum‐style BN254/Groth16 on‐chain cost model and an analytical depolarizing‐plus‐loss quantum‐resource model.
Quantum secret sharing (QSS) is a cryptographic protocol that leverages quantum mechanics to distribute a secret among multiple parties. With respect to the classical counterpart, in QSS, the secret is encoded into quantum states and shared by a dealer such that only an authorized subsets of participants, i.e., the players, can reconstruct it. Several state-of-the-art studies aim to transpose classical secret sharing into the quantum realm, while maintaining their reliance on traditional network topologies (e.g., star, ring, and fully connected), and require that all thenplayers calculate the secret. These studies exploit the Greenberger–Horne–Zeilinger state, which is a type of maximally entangled quantum state involving three or more qubits. However, none of these works account for redundancy, enhanced security/privacy features, or authentication mechanisms able to fingerprint players. To address these gaps, in this article, we introduce a new concept of QSS, which leans on a generic distributed quantum network, based on a threshold scheme, where all the players collaborate also to the routing of quantum information among them. The dealer, by exploiting a custom flexible weighting system, takes advantage of a newly defined quantum Dijkstra algorithm to select the most suitable subset oftplayers, out of the entire set onnplayers, to involve in the computation. To fingerprint and authenticate users, CRYSTAL-Kyber primitives are adopted, while also protecting each player’s privacy by hiding their identities. We show the effectiveness and performance of the proposed protocol by testing it against the main classical and quantum attacks, thereby improving the state-of-the-art security measures.
Quantum Secret Sharing (QSS) is an essential cryptographic primitive that distributes a secret among multiple parties using quantum information, ensuring that only authorized subsets of participants can reconstruct the secret. Existing QSS approaches predominantly rely on conventional network topologies and maximally entangled states such as the often requiring full participation of all key aspects such as redundancy, authentication, and privacy. In this work, we propose a novel QSS framework built on a generic distributed quantum network that incorporates a threshold-based scheme, allowing any t out of n players to collaboratively reconstruct the secret. Our protocol introduces a custom weighting system and a quantum variant of Dijkstra’s algorithm to dynamically select the optimal subset of players, enhancing flexibility and performance. Furthermore, we integrate CRYSTAL-Kyber post-quantum cryptographic primitives to provide robust user authentication and identity obfuscation, thereby bolstering security and privacy. Through comprehensive security analysis and simulations, we demonstrate that our protocol outperforms traditional QSS models, offering improved resilience against both classical and quantum adversarial threats.
We present a new framework for constructing practically efficient publicly verifiable secret sharing (PVSS) with non-interactive dealers , in that the dealer may go offline after sending a single message, and is not involved in the share verification process. We use identity-based encryption (IBE) and commitments as the main ingredients and avoid expensive zero-knowledge proofs. By instantiating them with post-quantum secure schemes, a lattice-based IBE and a hash-based commitment, we obtain our first construction: a post-quantum secure PVSS with non-interactive dealers that outperforms the prior lattice-based practical construction by Gentry et al. [Eurocrypt 2022]. However, to enable the aggregation of PVSS transcripts (which facilitates many additional applications such as secure voting), we propose our second construction by replacing hash-based commitments with Pedersen's homomorphic commitments. While this does not achieve full-fledged post-quantum security (as Pedersen's scheme is not quantum safe), it still provides privacy against a post-quantum adversary. We prove the security of this construction in a new model, which we call long-lasting security. This model guarantees that the protocol is secure in the present (pre-quantum era) while maintaining privacy in the long term (post-quantum era). This new model is of independent interest for constructing efficient schemes that are resilient to the harvest-now-decrypt-later line of attacks. In this model, we propose a blockchain-compatible secure voting scheme using our PVSS scheme. Our PVSS schemes demonstrate practical efficiency: our post-quantum PVSS shares a secret among 1024 receivers in 667 ms and verifies the dealing in < 5 ms, and communicates 4.4MB, overall whereas the state of the art [Gentry et al., Eurocrypt 2022] communicates 251MB and requires 2060s for dealing the secret.
The security of a secret sharing protocol is compromised if one or more dishonest participants can reconstruct the secret by deviating from the prescribed protocol, particularly when such malicious behavior remains undetected. Semi-Quantum Secret Sharing (SQSS) is a variant of secret sharing in which the participants possess only classical capabilities, such as preparing and measuring qubits in the computational (Z) basis, while a quantum-capable third party assists the dealer in generating and distributing quantum shares of a classical secret. The limited quantum capabilities of the participants in SQSS protocols may introduce vulnerabilities to collusion attacks, enabling an assisting quantum third party, in collaboration with a dishonest classical participant, to jointly recover the secret even without detection. In this work, we propose a novel SQSS protocol that eliminates this vulnerability and achieves information-theoretic security against collusion attacks. We further prove that the proposed protocol is secure against a broad class of external and internal attacks. Finally, a comparative analysis demonstrates that our construction advances existing SQSS protocols by simultaneously optimizing qubit efficiency, involves a classical dealer, and resilience against DCNA attacks using basic Bell states.
We present DQ-(5,11), a dealer-based (5,11) threshold quantum secret sharing (QSS) scheme where any 5 of the 11 participants can find a dealer's secret and 4 or fewer get nothing about it. A key point is that, due to the Cleve-Gottesman-Lo no-cloning bound, there is only a (k,n) threshold scheme for any quantum secret if n < 2k. Since 11≥10, is a (5,11) quantity, the threshold scheme is impossible for quantum secrets, and in any (5,11) quantum secret sharing scheme there is a classical secret that is encrypted in a way that is protected by quantum communication. DQ-(5,11) is a combination of Shamir's polynomial sharing over GF13 and a single-qudit reconstruction in dimension d=13. Each of the five cooperating participants in DQ-(5,11) performs one phase operation with the share of the quantum secret and a zero-sum mask so that the intermediate states will not have any partial sum. Decoy qudits from two mutually unbiased bases detect eavesdropping, and a dealer-published commitment lets participants check the reconstructed value. We achieve correctness of all 462 subsets of the network, information-theoretic secrecy against coalitions of up to four insiders and a requirement for the success of intercept-resend attacks to be (d+1)/2d)m for m decoys (8.6×10-9) for m=30). We use numerical data to verify the deterministic reconstruction for all 2,310 runs and show the effect of depolarizing noise (79.1% success at 5% noise at each stage) and channel loss. Furthermore, we compare our orbital-angular-momentum and time-bin qudit model to Trojan-horse countermeasures and other schemes.
Abstract With the rapid development of quantum computing, traditional encryption methods face growing security threats. Quantum Secret Sharing (QSS) has emerged as a promising solution, using quantum principles to improve communication security and prevent internal and external attacks. This study proposes a new (t, n) Threshold Quantum Secret Sharing (TQSS) protocol based on single-qubit unitary operations and Lagrange interpolation. The protocol allows secret reconstruction without third-party or dealer assistance and remains efficient even when some participants are absent. To address more complex real-world scenarios, we extend our previously proposed (t, n) TQSS protocol into a Conditional Dynamic TQSS (CDTQSS). This approach uses resource-based share splitting to allow new participants to join without requiring the dealer to redistribute information. However, the protocol is ‘conditional’ because existing participants must take on extra responsibility-they must assist in generating shares for new members and also participate in the secret reconstruction process together with them. The protocol maintains strong security, reduces resource consumption, and offers better flexibility, making it well-suited for practical and dynamic quantum communication needs.