commitment schemes

This study addresses the inherent tension between user privacy—encompassing anonymity, confidentiality, and unlinkability—and regulatory compliance—particularly auditability—in privacy-enhancing digital currencies, including cryptocurrencies and central bank digital currencies (CBDCs). Method: We propose a design-oriented privacy analysis framework, formalizing three generations of evolutionary models that systematically map privacy objectives to cryptographic primitives (e.g., zero-knowledge proofs, ring signatures, homomorphic encryption), protocol mechanisms, and system architectures. Our analysis draws on a horizontal comparison of over 120 privacy-preserving schemes. Contribution/Results: We identify three critical technical bottlenecks: cryptographic construction limitations, consensus mechanism constraints, and inadequate regulatory interface design. The framework yields a practical, implementable technology roadmap for next-generation CBDCs—informing system design, policy formulation, and international standardization efforts aimed at reconciling privacy protection with lawful oversight.

Traditional commit-reveal schemes are vulnerable to the “last-revealer attack,” wherein malicious participants delay revealing their commitments to bias the resulting randomness—compromising security in validator elections, zero-knowledge proof generation, and DeFi applications. To address this, we propose a two-layer commit-reveal protocol: the first layer collects commitments and randomizes the revelation order; the second layer generates the final randomness deterministically from the ordered revelations. We integrate lightweight offline P2P coordination to minimize network overhead. Our design is the first to systematically eliminate the last-revealer attack surface. A prototype implementation demonstrates a 37% reduction in communication cost compared to baseline schemes, exhibits Byzantine fault tolerance, and maintains compatibility with mainstream blockchain platforms. The reference implementation is open-sourced.

This work addresses the frequent disconnect between the mathematical certainty of numerical values in cryptographic protocols and their concrete representations, which undermines interoperability and formal verification. Drawing from representation theory, the paper introduces three classes of representations—algorithmically approximable, finitely precisely describable, and canonically normalizable—and proves that no universal computable canonicalizer can transform arbitrary approximate programs into a unique finite encoding. It extends the canonical encoding paradigm of the rational number system Σ_Q to practical cryptographic objects. By integrating computability theory with canonical serialization techniques, the approach is applied to symmetric and asymmetric encryption, hashing, and blockchain integrity protocols. Case studies such as Snaproot demonstrate that canonical representations are essential for achieving precise protocol specifications, ensuring interoperability, and enabling byte-level correctness arguments.

This paper addresses the inherent tension between transaction transparency and user privacy in public blockchains by proposing a trustless on-chain privacy-preserving transaction scheme. Methodologically, it designs a privacy architecture integrating Twisted ElGamal elliptic-curve commitments with EC Diffie-Hellman key exchange, and employs zk-SNARKs to enable publicly verifiable encryption, decryption, and commitment procedures. The core contribution is the construction of cWETH—a composable, Ethereum-compatible privacy-preserving wrapped asset—that achieves end-to-end hiding of transaction amounts and participant identities on a fully transparent ledger, while preserving public verifiability of transaction validity. Experimental evaluation demonstrates that the scheme significantly enhances the practicality and security of on-chain private transactions without compromising decentralization or composability.

This work addresses the challenge of enabling efficient, trustless off-chain double-spending prevention while preserving privacy for both users and service providers. To this end, the authors propose a modular off-chain execution layer that leverages a public-key-based token ownership model combined with a novel multi-public-key signature scheme. This design supports stable identities and transaction unlinkability while minimizing key management overhead. Through a formal security model, the system is proven to satisfy three core properties: double-spending resistance, censorship resistance (non-blocking), and bidirectional privacy. Notably, this is the first construction to achieve a private off-chain payment mechanism that simultaneously offers high efficiency and rigorous security guarantees under a general cryptographic setting.

To address the secure and trustworthy release of conditional information—such as electronic voting results—under specific spatiotemporal constraints, this paper proposes the first decentralized conditional information release system supporting *reveal verifiability*. Methodologically, it integrates time-release encryption with verifiable secret sharing to design a high-precision, trustless timing-based decryption mechanism, formally verified for security using Tamarin. Blockchain-based smart contracts enable cross-scenario key validation and globally distributed deployment. Contributions include: (1) the first reveal-verifiable secret sharing scheme; (2) a practical, formally verified time-release cryptosystem; and (3) empirical validation within a real-election-data-driven e-voting system, demonstrating significant improvements in security, fairness, and auditability of the voting process.

This work addresses the vulnerability of encrypted mempools to economically lagging and security risks arising from self-authorized state manipulation—such as perpetual contract funding rate manipulation—due to their inability to inject corrective transactions into already committed batches, despite offering protection against victim-dependent MEV attacks. The paper proposes a micro-correction mechanism grounded in executable arbitrage, modeling how correctors optimally choose order sizes balancing price impact and inventory costs, while evaluating exploitable opportunities through the lens of protocol disclosure timing. It introduces a novel local security index incorporating attacker blind spots, correction shielding, and capitalization shielding, revealing how private transactions suppress predictive capitalization of funding rates and induce dual amplification effects. By integrating game theory, market mechanism design, and encrypted mempool architecture, the study establishes a dynamic security framework driven by information scheduling and response factors, proving that closed-phase correction rates fall below adaptive correction rates and quantifying both state distortion and its responsive amplification.

This work addresses the challenge of enabling secure and programmable spending conditions without relying on consensus participants. To this end, we introduce, for the first time, a predicate mechanism into the Unicity model, extending token ownership to programmable spending predicates executed off-chain by dependent parties. This extension preserves the original system’s security guarantees while supporting off-chain smart contract functionality. Leveraging the unforgeability of predicate families, we construct a formally secure spending model and design a complementary off-chain execution architecture together with an atomic swap protocol. Our approach successfully realizes trustless atomic swaps, demonstrating the practical applicability of the proposed framework.

This work addresses the challenge of achieving transaction privacy on Algorand—a high-throughput public blockchain—where smart contracts face severe resource constraints and lack global state-based concurrency control. The authors propose a decentralized, non-custodial privacy protocol that leverages LSAG ring signatures with on-chain verification to ensure anonymity. Innovatively, they replace the conventional global Merkle accumulator with an O(1) commitment membership check based on Box Storage. To overcome opcode budget limitations, an embedded application call pool is introduced for dynamic budget expansion, enabling, for the first time on Algorand, efficient signature-obfuscating privacy without trusted setup. By integrating BN254-based cryptography with lightweight on-chain verification, the protocol delivers strong privacy guarantees and selective auditability while preserving Algorand’s high throughput, all without relying on zk-SNARKs or trusted setup assumptions.

This work addresses a critical incentive misalignment in existing Proof-of-Stake (PoS) blockchains, where validators receive identical rewards regardless of their actual contribution to proof validation. To remedy this, the paper introduces a novel consensus mechanism that defines a validator’s voting weight as the product of its staked stake and a reputation factor derived from the quality of its proof-generation work—thereby embedding proof quality directly into consensus weight computation for the first time. The proposed scheme employs an additive, fee-weighted, non-transferable, and round-limited reputation update rule, integrated within a Byzantine Fault Tolerant (BFT) framework alongside an adaptive burning ratio, forming a six-layer defense against Sybil and reputation-gaming attacks. The authors prove a significant lower bound on the economic cost of reputation manipulation. Under recommended parameters (r_max/r_min ∈ [4,10]), the cost for capital-rich adversaries to mount attacks increases by 4–10× compared to pure PoS, while preserving BFT safety and liveness guarantees.