Public blockchains impose an inherent tension between regulatory compliance and user privacy. Existing on-chain identity solutions require centralized KYC attestors, specialized hardware, or Decentralized Identifier (DID) frameworks needing entirely new credential infrastructure. Meanwhile, over four billion active X.509 certificates constitute a globally deployed, government-grade trust infrastructure largely unexploited for decentralized identity. This paper presents zk-X509, a privacy-preserving identity system bridging legacy Public Key Infrastructure (PKI) with public ledgers via a RISC-V zero-knowledge virtual machine (zkVM). Users prove ownership of standard X.509 certificates without revealing private keys or personal identifiers. Crucially, the private key never enters the ZK circuit; ownership is proven via OS keychain signature delegation (macOS Security.framework, Windows CNG). The circuit verifies certificate chain validity, temporal validity, key ownership, trustless CRL revocation, blockchain address binding, and Sybil-resistant nullifier generation. It commits 13 public values, including a Certificate Authority (CA) Merkle root hiding the issuing CA, and four selective disclosure hashes. We formalize eight security properties under a Dolev-Yao adversary with game-based definitions and reductions to sEUF-CMA, SHA-256 collision resistance, and ZK soundness. Evaluated on the SP1 zkVM, the system achieves 11.8M cycles for ECDSA P-256 (17.4M for RSA-2048), with on-chain Groth16 verification costing ~300K gas. By leveraging certificates deployed at scale across jurisdictions, zk-X509 enables adoption without new trust establishment, complementing emerging DID-based systems.
Document authentication remains a pressing challenge in various domains, including financial services, academic credentialing, healthcare, and supply chain management. Existing centralized verification systems are vulnerable to manipulation, inefficiency, and limited transparency. Blockchain technology, with its immutability and tamper-resistant capabilities, offers a strong decentralized alternative; however, many current implementations lack structured, issuer-bound relationships for documents. This paper proposes a blockchain-based model that leverages a hierarchical token structure to authenticate and trace the provenance of high-value digital documents, with a focus on financial records. The model introduces the concept of an issuer-bound parent token and document-linked child tokens, enforcing a structured trust relationship between a legitimate institution and the documents it issues. By combining on-chain cryptographic hashing with off-chain file references, the approach is designed to balance verifiability with scalability. We implement a proof-of-concept using Ethereum-compatible smart contracts on a permissioned blockchain and evaluate it in a consortium-style financial setting. Our functional analyses demonstrate the model’s ability to ensure document integrity, provenance, and resistance to document fraud. This work offers a practical and extensible foundation for secure digital document authentication and verification in financial and other trust-sensitive settings.
Open access
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
Abstract: Remote electronic voting systems require tamper-evident records of ballot submissions, yet the ledger integrity problem - ensuring that the record cannot be silently altered after the fact - has received less formal treatment than ballot-phase cryptography. Existing approaches rely on distributed blockchain consensus, digital signatures on bulletin boards, or external hash-tree timestamping services, each introducing dependencies on specialized infrastructure, continuously trusted parties, or computationally intensive proof systems. This paper provides a formal security analysis of a hash-chained append-only ledger instantiated in a standard relational database with quorum replication, establishing that equivalent tamper-evidence guarantees are achievable under the sole assumption of collision resistance of the instantiated hash function. We define five security properties in the Bellare-Rogaway game-based framework. Tamper-evidence (Proposition 1) bounds any PPT adversary's advantage at 2q(λ) · Adv^CR_H, with a tight reduction to collision resistance. Fork-resistance (Proposition 2) establishes that an adversary corrupting fewer than a quorum threshold of replicas cannot cause divergent chain histories at honest replicas. Retrospective modification resistance (Proposition 3) establishes that post-close modifications are detectable by any auditor holding a real-time replica copy. Cross-ledger binding security (Proposition 4) extends these results to the dual-ledger construction of the Arcaunt architecture, in which a public ballot ledger and a temporal credential ledger are cryptographically bound at insert time, making modifications to either detectable through the other with advantage bounded by 4q(λ) · Adv^CR_H. Selector integrity (Proposition 5) establishes that the last-valid-vote rule - operating on insertion sequence rather than timestamps, making it immune to clock manipulation - is integrity-secure conditional on credential security, formally delineating the boundary between ledger and credential security domains. We apply an eight-metric comparative framework to seven e-voting integrity architectures - hash-chaining, bulletin boards, homomorphic tallying, mixnet-based systems, blockchain, KSI timestamping, and VVPAT hybrids - establishing three findings: tamper-evidence basis is universal but mechanism-specific; fork-resistance is architecturally necessary specifically for revoting-based systems; and auditability complexity is inversely correlated with cryptographic sophistication. The hash-chained relational ledger achieves collision-resistance-based tamper-evidence with O(n) verification accessible to any SQL-capable auditor - a design point unoccupied by existing systems under the same combination of properties. Prototype validation on a Firebird 5.0 implementation confirms that each proposition is instantiated by a specific database trigger mechanism, with 6ms mean ballot submission latency and O(n) verification complexity empirically confirmed.
Web3 authentication stacks largely inherit ECDSA centric single-signature workflows that limit security and efficiency, while custody of identity data often remains application controlled rather than self-sovereign. We present S-Auth, an authentication layer that combines BIP340 Schnorr signatures with Decentralized Identifiers (DID), Verifiable Credentials (VC), and Content addressing (CID). The proposed solution utilizes Schnorr digital signatures, which have demonstrated improved security and efficiency over traditional schemes. The contributions of this work are as follows. Firstly, we apply the BIP340 standard to Schnorr digital signatures, bolstering security against various attacks including strong unforgeability under chosen message attack (SUF-CMA), non-malleability, linearity, related-key at tacks, hash collision, fault injection, nonce exfiltration, resource exhaustion, and domain separation. Secondly, we leverage the linearity property of Schnorr signatures to enable multi-signature aggregation and batch verification, addressing the inefficiency of existing schemes that rely on single signatures and thereby also enhancing privacy. Third, we combine the blockchain with DID, VC, and IPFS to provide a secure and self-sovereign identity that can be authenticated. Experiments comparing ECDSA, Ed25519, Schnorr, and BIP340 show that S-Auth reduces signature artifacts via aggregation, improves verifier throughput with batching, and decreases anchoring overhead while preserving user-controlled identity. S-Auth provides a self-sovereign, efficient, and secure authentication mechanism suitable for Web3 environments.
Password-based authentication systems remain the most widely used method for user verification despite being highly susceptible to offline dictionary attacks. To mitigate such attacks, server-aided password-based authentication schemes utilize an independent server, which helps to harden the credentials to be stored on the website database. Existing server-aided password-based authentication schemes rely on number-theoretic assumptions that are vulnerable to quantum-enabled adversaries and incorporate complex computations such as bilinear pairings, exponentiation, and Zero-Knowledge Proofs. In this work, we introduce a novel post-quantum secure server-aided password-based authentication scheme based on the Module Learning With Errors (M-LWE) problem. A defining feature of our protocol is its complete operational transparency as it integrates with existing web interfaces without requiring users to modify their login behaviour or perform additional computation. To ensure long-term resilience, our scheme includes a transparent key rotation mechanism that allows service providers to update the entire credential database with a fresh secret key without user intervention. We provide a formal security analysis in the Real-or-Random (RoR) framework. This analysis demonstrates that our protocol's resistance to offline dictionary attacks reduces to the underlying hardness of the M-LWE problem, and the system achieves forward secrecy through a key rotation mechanism. Through an optimized Number Theoretic Transformation (NTT)-based implementation for faster polynomial multiplications, our empirical analysis demonstrates high computational efficiency, with average registration and authentication latencies of 0.88 ms and 0.96 ms, respectively.
Jae Hyun Choi, Geontae Noh, Ji Young Chun, Ik Rae Jeong
Regulatory frameworks like MiCA mandate KYC and auditability for stablecoins, but existing solutions fail to simultaneously achieve privacy, compliance, and cross-chain compatibility. We propose zkA3 (Zero-Knowledge Address Abstraction with Auditability), enabling users to generate pseudonymous identifiers from web2 certificates with unlinkability guarantees while incorporating encrypted audit tokens for authorized identity tracing. We formally prove five security properties: pseudonymity, unlinkability, zero-knowledge authentication, auditability, and cross-chain consistency. Our implementation achieves 29.8ms proof generation with 9,917 constraints, demonstrating practical feasibility. zkA3 is the first scheme simultaneously supporting privacy-preserving cross-chain stablecoin operations and regulatory compliance.
Mr. Utsav Pandey, Ms. Sania Parkar, Mr. Anant Sarode, Prof. Amit Chakrawarti
Traditional banking systems rely on passwords, PINs, and centralized biometric storage, exposing users to phishing, SIM-swap attacks, and credential reuse vulnerabilities. This paper presents the ZKP Banking Interface, a pinless, context-aware financial authentication system built on Zero-Knowledge Proof (ZKP) technology. A unified ZK-SNARK circuit (Groth16), implemented in Circom, encodes three simultaneous security factors: identity commitment, trusted network context, and transaction threshold logic using Poseidon hashing. Conditional biometric and puzzle challenges are enforced cryptographically for higher-risk scenarios. Proof generation and verification are fully automated within the browser using snarkJS and WebAssembly artifacts, eliminating manual proof handling. The system supports two verification modes: local (device-only privacy) and on-chain (public auditability via a Solidity smart contract on a Hardhat network). Experimental evaluation across five test scenarios confirms correct contextual policy enforcement, successful proof validation in both modes, and a smooth, practical banking user experience. The proposed system demonstrates that ZKP-based authentication can replace traditional credentials while maintaining strong privacy guarantees.
Reputation systems are fundamental to fostering trust and cooperation in digital environments, yet existing solutions often struggle with centralization, vulnerability to manipulation, and limited portability. Centralized reputation platforms can be opaque, censored and susceptible to become single points of failure, while decentralized ones face challenges, such as Sybil attacks, malicious strategies (e.g., ballot stuffing, bad-mouthing) exercised by entities of high influence, i.e. "whales", and privacy concerns. This paper addresses these persistent issues by proposing a blockchain-based reputation framework that integrates robust identity verification, square root voting constraints, and dynamic stake-based incentives. Rating power is linked to the reputation of the rater that puts its reputation at stake. The model aims to ensure that reputation is earned and maintained through verifiable, community-aligned actions, while simultaneously limiting the potential for abuse by malicious actors or disproportionately influential participants. By leveraging decentralized identifiers, zero-knowledge proofs, and transparent incentive mechanisms, the proposed system seeks to balance transparency, fairness, and privacy. Extensive simulation experiments prove that the approach is effective to reveal the true quality of entities, even in presence of 49% colluding voters. The approach is designed to be adaptable across diverse domains, ranging from marketplaces and collaborative platforms to decentralized finance and governance.
This work proposes TLS2VC, a decentralized WebProof framework that distributes trust across multiple Notaries. Notaries attest to TLS session authenticity—server identity and encrypted transcript integrity—without accessing plaintext, then issue Verifiable Credentials (VCs) that Verifiers can validate. To prevent concentration of malicious Notaries, we employ verifiable random selection via Verifiable Random Function (VRF) combined with threshold signatures. We provide probabilistic security analysis showing that honest Notaries are included with high probability, and derive formulas to compute the minimum number of Notaries k required for a target security level. A lightweight prototype demonstrates practical feasibility, enabling reuse of existing web information as trusted credentials in Web3 and self-sovereign identity environments.
K. Sundara Krishnan, R. Chithra Devi, Christo Ananth, D. Easwaramoorthy · 8 authors
E-commerce platforms incorporate reviews and reputation systems, allowing retailers and customers to manage and track their financial transactions. Consequently, it is crucial to design a reliable reputation system for the e-commerce environment, as it faces well-documented threats, including sybil attacks, feedback collusion, impersonation, review tampering, and whitewashing attacks. Current centralized systems are vulnerable to impersonation attacks, feedback manipulation, and lack automated verification against collusion-based reputation distortion. These unwanted ratings and reviews are highly correlated with abnormal cyber-attacks that damage both seller reputations and buyer experiences. To address these challenges, we propose a Blockchain-based Two-Level E-Commerce Trustable Reputation Framework (BTL-ETRF) utilizing deep learning-embedded transformers and redactable blockchain systems. Initially, we implement Multi-Factor Authentication for e-commerce users, utilizing three factors: PIN, OTP, and biometric fingerprint, to mitigate impersonation attacks. Only authenticated users are allowed to proceed to the reputation verification stage, where the proposed work considers five major metrics to classify user reputation using the Residual Dilated Convolution Transformer. To automate the reputation verification process, we design and employ two smart contracts, the Authentication Smart Contract and the Reputation Smart Contract which trigger automated actions based on the BTL-ETRF results. All transactions include reputation classification, and triggered actions are stored in the redactable blockchain, which can modify the stored transactions if needed. Finally, we demonstrate the performance of the proposed BTL-ETRF using Python and Ethereum Solidity, and conduct a formal analysis that shows the proposed model outperforms the compared works.
The rapid adoption of digital healthcare systems has significantly increased the use of Electronic Health Records (EHR), online appointment platforms, and digital prescription management. While these technologies enhance accessibility and operational efficiency, they also introduce critical challenges related to data confidentiality, secure authentication, record integrity, and protection against unauthorized access. Healthcare data contains highly sensitive personal and medical information, making security a primary concern. Ensuring secure communication and verified access between patients and doctors remains a major challenge in maintaining trust and privacy within digital healthcare environments. Many existing healthcare management systems rely on centralized storage models and basic authentication mechanisms, exposing them to risks such as data breaches, impersonation attacks, and unauthorized record modification. Although basic encryption mechanisms may be applied to protect stored data, key management and authentication processes often rely on standard approaches without decentralized verification or advanced cryptographic reinforcement. As a result, centralized architecture creates a single point of failure, increasing vulnerability to unauthorized access, data tampering, and weak identity verification. Limited transparency and auditability further restrict effective monitoring of data usage and system activities. To address these issues, the proposed system introduces Quantum Crypt (QC), a hybrid security approach that integrates blockchain technology with Post-Quantum Cryptography (PQC) concepts and advanced encryption mechanisms. Medical reports and prescriptions are secured using the Advanced Encryption Standard in Cipher Block Chaining mode (AES-CBC), with encryption keys generated through a quantum-inspired mechanism. Authentication is enhanced through a lattice-inspired model implemented via Qiskit-based quantum circuit simulation to ensure secure key validation between patients and doctors. Blockchain integration using Web3 and smart contracts ensures immutable storage of healthcare records, improving transparency, strengthening data integrity, and enabling controlled access within the digital healthcare ecosystem.
Traditional selling systems often limit products to local markets and rely heavily on intermediaries, resulting in reduced profit margins, inconsistent quality, and limited market reach. Maintaining consistent quality and ensuring market transparency remain significant challenges in these legacy frameworks. To address these issues, this project proposes a secure and efficient Double Auction System for multi-category product trading. To enhance security, privacy, and trust, the project integrates advanced cryptographic mechanisms. zk-SNARKs (Zero-Knowledge Succinct Non- Interactive Arguments of Knowledge) are employed for sealed bidding, ensuring that both bidder identities and bid values remain hidden while maintaining mathematical verifiability. Conversely, Linked Ring Signatures are used for open bidding, allowing bid values to remain transparent while masking the identities of the bidders. A Commit-Reveal Scheme is implemented to prevent bid manipulation and ensure fairness during the submission phase. Additionally, a Reputation Score Algorithm incentivizes honest participation by rewarding users with a trust score based on their historical behavior. Finally, Blockchain technology is integrated via a private blockchain to record all auction data and reports in an immutable and tamper-proof manner. This multi-layered approach ensures a fair, secure, and sustainable trading ecosystem, benefiting both producers and buyers across diverse sectors.
The rapid evolution of cloud computing has revolutionized digital data storage and sharing, enabling users to access information anytime and anywhere. Despite these advantages, cloud-based systems face major challenges related to data security, privacy protection, and trust management, particularly when handling sensitive user information. Conventional cloud storage solutions operate on centralized architectures, where a single cloud service provider manages and controls the stored data. This centralized model introduces significant risks, including single points of failure, unauthorized data access, data manipulation, and limited visibility into data-sharing activities. In many traditional systems, data protection mechanisms rely on basic encryption methods without strong auditing or verification features, leaving them vulnerable to insider attacks and external cyber threats. Furthermore, the absence of immutable transaction records and robust key management practices reduces accountability and weakens user confidence in cloud environments. To address these shortcomings, the proposed system presents a secure cloud data sharing framework that combines Elliptic Curve Cryptography (ECC) with blockchain technology. In this approach, user files are encrypted using ECC before being uploaded to the cloud, ensuring strong data confidentiality and protection against unauthorized access. Simultaneously, blockchain technology is employed to record file metadata and transaction details in a decentralized and tamper-resistant ledger, enabling transparent and verifiable audit trails. The decentralized architecture eliminates reliance on a single authority, enhances trust, and prevents unauthorized modification of stored records. Additionally, secure authentication and controlled access mechanisms further reinforce system security. By integrating advanced cryptographic encryption with decentralized verification, the proposed solution enhances data integrity, improves transparency, and establishes a reliable and accountable framework for secure cloud data sharing.
Privacy-preserving aggregation is a cornerstone for AI systems that learn from distributed data without exposing individual records, especially in federated learning and telemetry. Existing two-server protocols (e.g., Prio and successors) set a practical baseline by validating inputs while preventing any single party from learning users' values, but they impose symmetric costs on both servers and communication that scales with the per-client input dimension $L$. Modern learning tasks routinely involve dimensionalities $L$ in the tens to hundreds of millions of model parameters. We present TAPAS, a two-server asymmetric private aggregation scheme that addresses these limitations along four dimensions: (i) no trusted setup or preprocessing, (ii) server-side communication that is independent of $L$ (iii) post-quantum security based solely on standard lattice assumptions (LWE, SIS), and (iv) stronger robustness with identifiable abort and full malicious security for the servers. A key design choice is intentional asymmetry: one server bears the $O(L)$ aggregation and verification work, while the other operates as a lightweight facilitator with computation independent of $L$. This reduces total cost, enables the secondary server to run on commodity hardware, and strengthens the non-collusion assumption of the servers. One of our main contributions is a suite of new and efficient lattice-based zero-knowledge proofs; to our knowledge, we are the first to establish privacy and correctness with identifiable abort in the two-server setting.
Modern digital financial systems continuously face the fundamental trilemma of transaction confidentiality, computational efficiency, and cryptographic security. While existing blockchain technologies have made significant progress in security and decentralization, they are limited in ensuring confidentiality of financial information due to their public distributed ledger structure. To overcome these limitations, we present Epsilon, an innovative protocol that fundamentally addresses this complexity by directly combining Elliptic Curve-based Partially Homomorphic Encryption with parallel processing architectures. This paper introduces the Cryptora Protocol, a complete end-to-end operational framework that implements a two-tiered architecture where transaction processing is performed off-chain in a peer-to-peer manner, with results recorded on smart contract-based on-chain distributed ledgers. Our experimental results demonstrate that Epsilon achieves 500,000 TPS with end-to-end latency of 50-100ms while maintaining strong cryptographic guarantees including semantic security, unlinkability, and double-spending resistance.
We present COMET-MPC (Commitment-Oriented Multi-Party Computation with Equality Testing), a novel MPC framework that fundamentally reimagines multi-party computation as a commitment verification problem rather than a traditional secret-sharing problem. COMET-MPC achieves dealerless, one-round setup by reducing all MPC coordination tasks—input binding, consistency verification, and replay prevention—to homomorphic equality testing over elliptic-curve commitments. Unlike classical MPC protocols (Shamir’s secret sharing, FROST) that require multi-round polynomial verification or interactive zero-knowledge proofs, COMET-MPC performs verification through a single algebraic check: testing whether a group element equals the identity. This zero-detection paradigm exploits the structural identity between EC-Pedersen commitments and EC-ElGamal ciphertexts, enabling decrypt-free verification with perfect correctness and computational hiding under the Decisional Diffie-Hellman (DDH) assumption. We provide complete algorithmic specifications, formal security proofs including binding, hiding, replay resistance, and a rigorous security level analysis demonstrating ≈ 128-bit security for standard 256-bit elliptic curves. COMET-MPC is particularly suited for real-world ledger systems, authentication protocols, confidential databases, and privacy-preserving regulatory compliance where minimal interaction, minimal trust, and minimal leakage are paramount.
Recently, developing technologies for smart cities, although scalable and cost-effective, have been challenging to provide anonymous verification and on-chain integrity with low overhead due to the increasing attack surface. We propose ZkPSLB, a layered end-to-end security framework to address the problem. ZkPSLB utilizes a Zero-Knowledge Concise Non-Interactive Knowledge Argument (zk-SNARK), a type of Zero-Knowledge Proof (ZKP) scheme, embedded within the Constrained Application Protocol (CoAP) for anonymous device authentication. Sensor payloads are encrypted with elliptic curve cryptography (ECC) and stored in a decentralized cloud storage system (IPFS). IPFS CIDs are committed to the chain, ensuring both off-chain confidentiality and on-chain integrity. In the evaluation conducted with 500 devices/5000 metadata, the authentication communication overhead was measured at 1952 bits. The event-based smart contract (EBSC) reduces on-chain payload and gas growth compared to storage-based designs, and its cost advantage has been validated.
Seung Kwon Lee, Seok Bin Son, Joongheon Kim, Hoh Peter In
Quantum machine learning (QML) has attracted growing interest for their ability to achieve superior performance with significantly fewer parameters. However, the high cost and scarcity of current hardware push inference to cloud-hosted quantum devices, creating a tension between verifiability and confidentiality. This work proposes a novel framework that converts quantum neural network operations into classical arithmetic circuits that faithfully approximate genuine quantum computations. By encrypting these circuits with zero-knowledge proofs, it ensures computational validity while concealing internal parameters. Experimental results show that our classical circuits achieve fidelity above 0.9996 and total variation distance below 1% compared to actual quantum computations, verifying the practicality of trustworthy and privacy-preserving quantum inference.
Open access
Quantum Computing Algorithms and Architecture
Physical Unclonable Functions (PUFs) and Hardware Security
Abstract E-commerce platforms are increasingly targeted by sophisticated cyber-attacks that exploit the inherent vulnerabilities of centralised authentication architectures. Password-based systems, two-factor authentication, and centralised identity stores have demonstrated persistent susceptibility to phishing, credential stuffing, man-in-the-middle interception, and large-scale data breaches. This paper investigates the design, implementation, and evaluation of a blockchain-based authentication system as a structural response to these limitations. The proposed system leverages Ethereum’s public-key cryptographic infrastructure, MetaMask wallet integration, Web3.js, JSON Web Tokens (JWT), React.js, and Node.js to deliver a decentralised, tamper-proof, and privacy-preserving authentication flow for e-commerce applications. A proof-of-concept prototype was built and evaluated against conventional authentication methods across eleven analytical dimensions, including security architecture, data integrity, identity management, scalability, trust models, and regulatory alignment. Results confirm that the blockchain-based approach eliminates credential database attack surfaces, enables non-repudiable transaction signing, supports Zero-Knowledge Proof (ZKP) verification, and implements Self-Sovereign Identity (SSI) principles that return data ownership to users. Scalability under high transaction volumes and user onboarding complexity are identified as the primary adoption barriers, suggesting that hybrid architectures may offer the most pragmatic near-term deployment pathway. The study contributes an empirically grounded, real-world implementation perspective to the growing literature on blockchain security applications, and provides actionable guidance for e-commerce operators, security practitioners, and researchers exploring decentralised identity systems. Keywords Blockchain Authentication, E-Commerce Security, Ethereum, Metamask, Decentralised Identity, Zero-Knowledge Proofs, Self-Sovereign Identity, JWT, Smart Contracts, Credential Stuffing, Public-Key Cryptography.
Integrating third-party Machine Learning (ML) models into industrial Operational Technology (OT) creates a procurement deadlock: operators cannot verify vendor performance claims without sharing representative evaluation data with vendors, while vendors refuse to reveal proprietary model weights before purchase, rendering traditional safeguards such as Non-Disclosure Agreements technically unenforceable. This paper introduces a framework combining Zero-Knowledge Proofs (ZKPs) with smart contracts to enable trust-minimized, cryptographically verifiable competitive model procurement in Industrial Cyber-Physical Systems (ICPS). Vendors cryptographically prove that their model outperforms a legacy baseline without disclosing proprietary weights, a process we term cryptographic performance attestation, while the on-chain workflow automates escrow, proof verification, and best-vendor selection with arbiter-based dispute resolution. ZKP privacy is scoped to vendor model weights; operator-side evaluation-data confidentiality is managed separately via synthetic, de-identified, or public benchmark data. We analyze three ZKP workflow variations and evaluate them on consumer-grade hardware, achieving proving times of approximately three seconds and sub-dollar on-chain verification costs under Layer-2 fee assumptions for the recommended single-proof variation, while identifying computational trade-offs of recursive proof aggregation. The entire verification phase operates offline with no impact on real-time OT control paths, bridging the IT/OT pre-transaction trust gap while deferring artifact deployment to existing OT tooling.
Tourism relies on central review platforms which produces three major systemic issues that include fake content, unclear moderation activities and inadequate compensation systems for authentic consumer contributions. TrustChain resolves industry review challenges using a blockchain formation that combines Layer-2 scaling solutions with zero-knowledge proofs (ZKPs) and tokenized governance system. The transaction cost reductions are huge following the implementation of a Proof-of-Stake consensus system on the Polygon-based architecture although the system maintains confirmation times shorter than 2 seconds. The implementation of Self-Sovereign Identity framework alongside transaction-linking smart contracts maintains highly accurate review authenticity in prototype evaluations through TripAdvisor datasets. Through its DAO governance structure users can verify review authenticity by using multi-signature checks which resolve all major disputes in less than one day. The integration of IPFS for multimedia storage generates an 83% decline in blockchain bloat that does not affect cryptographic security.
Asmart-contract framework for patient identity management in digital health platforms. A major gap in current digital health ecosystems is the absence of a portable and verifiable patient identity layer across fragmented electronic health record (EHR) systems. The problem addressed is the lack of a portable, verifiable, and patient-centric identity layer across fragmented electronic health record systems, which weakens access accountability and privacy. The proposed solution couples fast healthcare interoperability resources (FHIR) with self-sovereign identity (SSI), storing FHIR payloads off-chain in the InterPlanetary file system (IPFS) and committing only encrypted pointers and policies on Polygon smart contracts. Patient identifiers and content addresses are protected with AES-256 GCMauthenticated encryption and elliptic-curve key wrapping (ECIES) for both the healthcare administrator and the patient. A web implementation in Next.js using thirdweb automates wallet creation, keystore handling, encryption, and on-chain commits. In evaluation with 50 synthetic registrations, success reached 100 percent, median end-to-end latency was 5.86 seconds, mean on-chain latency 3.77 seconds, average transaction fee 0.0401 POL/MATIC, encryption time 13.9 milliseconds, and all decryptions validated. The results indicate practical feasibility for portable identity and auditable access, with on-chain latency as the main bottleneck to be reduced through batching, cheaper layers, and broader field trials. However, this study is limited because the evaluation uses only synthetic data and singleprovider testing, without real-world patients or multi-institutional environments. Zero-knowledge proofs (ZKP) are discussed conceptually as future integration and are not implemented or benchmarked in this work.
Existing high performance blockchains verify one signature per transaction on the critical path, which creates O(N) verification cost, high hardware pressure, and difficult post quantum migration. This paper presents ACE Runtime, a ZKP native execution layer built on identity authorization separation. We replace per transaction signature checks with lightweight HMAC attestations in the hot path, then generate one aggregated zero knowledge finality certificate per block in an asynchronous prove stage. The system is organized as an Attest Execute Prove pipeline with two tier finality: soft finality from BFT voting and hard finality from proof verification. Under standard cryptographic assumptions, we provide formal arguments for attestation unforgeability and hard finality irreversibility. We also define a two phase timeout and backup proving path with witness availability gossip for liveness under builder failure. Quantitative results combine analytical modeling with reference implementation measurements. The prototype shows low CPU orchestration overhead, while model driven analysis projects constant per block verification cost, lower validator hardware requirements for non builders, and better bandwidth efficiency than per transaction signature designs. These results indicate that identity authorization separation is a practical architecture for sub second cryptographic finality with a clear path toward stronger post quantum components.
Post-quantum signature schemes impose kilobyte-scale on-chain artifacts. Verifying them inside ZK circuits merely relocates the cost via expensive lattice arithmetic in prover circuits. We present ZK-ACE (Zero-Knowledge Authorization for Cryptographic Entities), which replaces transaction-carried signature objects with identity-bound ZK statements. Given a deterministic identity derivation primitive (DIDP) as a black box, the prover demonstrates in zero knowledge that an identity consistent with an on-chain commitment authorized the transaction; no signature object is produced or verified on-chain. We provide game-based definitions and reduction-based proofs for authorization soundness, replay resistance, substitution resistance, and cross-domain separation, under knowledge soundness, collision resistance, and DIDP recovery hardness. Structural data accounting shows an order-of-magnitude reduction in per-transaction authorization data versus direct PQC deployment. A reference implementation offers two backends: Circle STARK (341 active rows / 361 AIR constraint expressions, 14.5 ms prove, 1.1 ms verify, approx. 107 KB proofs, transparent setup, post-quantum-oriented) and Groth16/BN254 (2,155 R1CS constraints, 37.3 ms prove, 128-byte proofs). Both are roughly 500--2,300x smaller than in-circuit PQC signature verification. Under mandatory per-block STARK aggregation, per-transaction consensus-visible data is approx. 160 bytes.