Dr. P. C. Prabhu Kumar, P. Poojitha, K. Satheesh Kumar, M. Charan Kumar · 6 authors
The rapid digital transformation of the healthcare and drug sector has increased the reliance on cloud infrastructures for storing and exchanging Electronic Health Records (EHRs), raising significant concerns regarding privacy breaches, unauthorized access, and data integrity. To overcome these challenges, this project proposes a secure, patient-centric medical and drug data-sharing framework that integrates blockchain technology with distributed cloud storage. In this system, patients upload encrypted Personal Health Records (PHRs) to an untrusted cloud server while maintaining complete control over access permissions. A semi-trusted Setup and Re-Encryption Server (SRS) manage cryptographic key generation and re-encryption processes, enabling healthcare providers to access only the data explicitly authorized by the patient. All access requests, key operations, and permission updates are immutably recorded on a blockchain ledger, ensuring transparency, traceability, and accountability. The design further enforces forward and backward access control, automatically revoking past privileges when permissions are modified. Experimental evaluation demonstrates that the framework effectively ensures confidentiality, integrity, and access control while resisting tampering and supporting efficient real-time medical services, making it a promising solution for secure and scalable e-Health data exchange.
With the growing volume of sensitive data stored and processed in cloud environments, conventional security models are no longer sufficient to guarantee privacy, integrity, and trust. This paper proposes a blockchain-based framework that integrates Zero-Knowledge Proofs (ZKPs) and homomorphic encryption (HE) to enable secure and privacy-preserving data sharing. ZKPs are employed to verify user access rights without exposing identities or underlying information, while HE allows computations to be performed directly on encrypted data, ensuring confidentiality is preserved throughout the data lifecycle. The proposed framework addresses the limitations of existing approaches that either lack encrypted computation capabilities or expose sensitive data during processing. Formal and informal analyses demonstrate the feasibility of the model in terms of encryption time, ZKP verification latency, and computation overhead. The framework is designed to be applied initially in the healthcare sector and aligns with national digital transformation initiatives such as Saudi Vision 2030.
The security of modern public-key cryptography generally relies on computational intractability assumptions, such as integer factorization and discrete logarithm problems. This paper proposes a fundamentally different foundation for security: the intrinsic mathematical properties of tensor product categories—globalentanglement, rigid decomposition, and sensitivity amplification—are directly employed as security resources of the cryptosystem. Within the modular representation category of finite simple groups over finite fields, the private key correspondsto an irreducible modular representation, while the public key was originally conceived as the character vector of a tensor product of that representation. However, this paper reveals a fatal structural vulnerability: because the character ofthe base representation is public, an adversary can fully recover the private keycharacter through trivial division, causing the original security assumption to collapse completely. To address this, the paper accomplishes a paradigm shift from“character-exposure cryptography” to “structure-commitment cryptography,” redefining the public key as a cryptographic commitment to the multiplicity vectorof the tensor product decomposition. Building upon this, the commitment-basedrepresentation recognition problem and the commitment-based tensor product decomposition problem are formalized, and their hardness is argued under both classical and quantum computational models. At the protocol level, it is pointed outthat non-interactive key exchange faces a fundamental obstacle due to the lack ofrepresentation-category homomorphic commitments; consequently, the research focus is shifted to digital signature schemes. The proposed TC-Sig scheme bridges thegap between commitment hiding and multiplicity verification using zero-knowledgeproof techniques, with security reduced to the commitment-based representationrecognition problem in the random oracle model. A feasibility assessment indicatesthat, for candidate groups such as the Mathieu group M12, key generation and commitment computation can be completed within milliseconds, while the introductionof zero-knowledge proofs increases latency to the order of seconds or minutes, making the scheme suitable for low-frequency, high-security scenarios. The security ofthis framework rests on three cornerstones: the classification rigidity of finite simple groups, the one-wayness of commitment schemes, and the non-abelian quantumcomputing barrier, thereby offering a new pathway for post-quantum cryptographyrooted in pure mathematical structure.
J. Rekha J. Rekha, N. Soujanya N. Soujanya, R. Sai Deepthi R. Sai Deepthi, S. Praveen Kumar S. Praveen Kumar · 6 authors
Cloud computing has revolutionized the way organizations and individuals store, process, and manage data by offering scalable and cost-effective solutions over the internet. However, despite its widespread adoption, cloud computing faces critical challenges related to data security, privacy, trust, and centralized control. Centralized cloud architectures are highly susceptible to cyber-attacks, unauthorized access, and data breaches, which can compromise sensitive information. To address these issues, this project proposes a blockchain-integrated cloud system called Cloud Chain, which leverages Ethereum blockchain technology to enhance security and trust in cloud environments.The proposed system utilizes smart contracts to automate access control and ensure secure data transactions. Blockchain provides an immutable and decentralized ledger, making it nearly impossible to alter stored data without detection. This system enables secure file storage, transparent data access, and efficient verification mechanisms. By integrating blockchain with cloud computing, the project enhances data integrity, reduces dependency on centralized authorities, and improves overall system reliability. The experimental results demonstrate that the proposed system provides a more secure and scalable solution compared to traditional cloud systems.
However, the centralized cloud storage poses a great threat to the security and privacy of the user. In the digital world, cloud storage is one of the most fundamental components of data storage and online services. In the traditional centralized approach, the data, including user information, credentials, and other access information, is stored centrally. This approach is highly vulnerable to attacks and data breaches. The main objective of the proposed research is to develop a system that improves the security, privacy, and control of the data, as well as providing a secure environment for storing and sharing digital assets. The system uses the Blockchain technology and the InterPlanetary File System (IPFS) to provide secure and tamper-proof storage. In the proposed system, Elliptic Curve Cryptography (ECC) is used to ensure the highest level of encryption using the smallest key sizes. In addition, the proxy re-encryption method is used to ensure the secure sharing of data among authorized users without revealing the original encryption keys. Zero-Knowledge Proof (ZKP) is used to ensure the highest level of privacy by verifying the user's authorization without revealing the actual credentials. The combination of decentralized storage, blockchain-based verification, and advanced cryptographic techniques provides a robust solution for mitigating cloud security threats, ensuring confidentiality, integrity, and transparency, and fostering a trustworthy environment for both individuals and organizations.
We establish an information-theoretic lower bound on the prover overhead of any zero-knowledge proof system that verifies arbitrary neural network inference. We prove a minimum multiplicative overhead of 2x for general circuits, rising to 4x for neural networks with ReLU activations due to activation encoding, weight commitment, and layer dependency costs. We further prove that composing ZK with fully homomorphic encryption produces multiplicative overhead blowup, making ZK+FHE verification impractical beyond approximately 10^4 gates. We survey six contemporary proof systems and show their observed overheads are consistent with our bounds. Our results formalize the intuition that free verification of AI computation is impossible and provide concrete bounds for system designers.
Open access
2 source records
Adversarial Robustness in Machine Learning
Cryptography and Data Security
Physical Unclonable Functions (PUFs) and Hardware Security
The rapid aging of the global population necessitates automated healthcare environments, yet current Intelligent Room architectures relying on centralized cloud servers face critical challenges regarding data opacity and single points of failure. This paper proposes a novel architecture that synergizes Distributed Ledger Technology (DLT) with Federated Learning (FL) to create a trustless, immutable audit trail for patient monitoring. Unlike traditional FL approaches, we introduce a blockchain-based aggregation mechanism that eliminates the central authority. Furthermore, to address the resource constraints of edge devices such as smartphones, we implement a specific Lightweight Neural Network (L-CNN) utilizing depthwise separable convolutions. The proposed system ensures that patient data remains local while model updates are cryptographically verified on-chain, offering a scalable, low-cost solution for resource-constrained healthcare environments.
P. Subramanya Sai, Bhukya Niranjan, Akula Tejaswini, A Varshitha · 5 authors
The exponential increase in digital data exchange and online communication has intensified the need for secure, transparent, and dependable file-sharing systems. Critical information such as financial records, healthcare data, confidential documents, and research outputs is frequently transmitted across distributed networks, where conventional centralized storage models introduce significant vulnerabilities. These traditional systems rely on single-point control, making them prone to data breaches, unauthorized access, service disruptions, and integrity violations. Furthermore, they lack transparency and robust audit mechanisms, raising concerns about data reliability and trustworthiness during storage and transmission. To overcome these limitations, this work proposes a decentralized and secure file-sharing framework that integrates blockchain technology, the Inter-Planetary File System (IPFS), and cryptographic techniques. The system ensures data confidentiality by encrypting files using the Elliptic Curve Integrated Encryption Scheme (ECIES) before storing them in the distributed IPFS network. Instead of placing the actual data on-chain, only essential metadata including file hash, ownership details, timestamps, and access permissions is maintained within a smart contract on the Ethereum blockchain. This design guarantees immutability, traceability, and protection against tampering, while enabling fine-grained access control. In addition to secure storage, the framework incorporates ChaCha20-based symmetric encryption to evaluate and compare computational performance with asymmetric methods. The combination of decentralized storage, cryptographic security, and immutable ledger technology eliminates reliance on centralized authorities, thereby reducing single points of failure and enhancing system resilience. The proposed approach ensures that only authorized entities can access and decrypt shared content while maintaining transparency of file transactions.
The rapid advancement of digital technologies in healthcare has increased the need for secure, transparent, and efficient management of medical data. However, most existing systems rely on centralized architectures, where sensitive patient information is controlled by a single authority. This creates vulnerabilities such as data breaches, unauthorized access, and single points of failure, which can compromise data integrity and patient privacy. The core problem addressed in this research is the lack of a decentralized and tamper-resistant mechanism for managing Electronic Health Records (EHR). Current solutions often suffer from limited transparency, inefficient data sharing between patients and doctors, risks of data manipulation, dependency on intermediaries, and scalability issues due to large medical files like reports and prescriptions. To address these challenges, this research proposes a blockchain-based healthcare management system integrated with the Inter-Planetary File System (IPFS). Blockchain technology, implemented using Ethereum and Web3, ensures secure, immutable, and transparent transaction handling through smart contracts. IPFS is used for decentralized storage of medical files, with only cryptographic hashes stored on the blockchain to reduce storage overhead while maintaining data integrity. The system enables patients to book appointments, upload medical reports, and securely share them with doctors. Doctors can access records, provide diagnoses, and generate prescriptions, which are also stored via IPFS and linked to the blockchain. This ensures that data cannot be altered without detection, enhancing trust. The proposed system improves data security, privacy, reliability, and scalability in healthcare data management.
In decentralized finance (DeFi), accidental cryptocurrency transfers to incorrect wallet addresses are a large usability and security issue, frequently causing permanent loss of funds. We present CryptoSafeSend, a smart contract-based safety protocol for transactions featuring a cryptographically secure passcode verification scheme supporting conditional transfers. This work addresses higher-level security issues by introducing a PBKDF2-based key derivation function, which generates strong encryption keys based on Firebase's Firebase Unique Identifier. Secret passcodes are encrypted in Advanced Encryption Standard operating in Galois/Counter Mode functions deployed underneath the Web Crypto API, and the initialization vector and ciphertext are Base64 encoded for off-chain reliable storage and Firebase Firestore-based messaging. The protocol prevents unauthorized exploitation by safely binding off-chain passcode transmission to a matching on-chain verification, reinforcing user trust without undermining decentralization. Also, to ensure recoverability, CryptoSafeSend integrates a 7-day on-chain escrow lock, after which unclaimed funds become permissionlessly refundable to the sender, preserving decentralization while eliminating reliance on trusted intermediaries. Testing on an Ethereum testnet confirms negligible gas overhead, immunity against double claims, and strong security guarantees, qualifying CryptoSafeSend as a valuable constituent in next-generation secure digital asset protocols.
Recent advancements, specifically the 2026 whitepaper by Google Quantum AI, Stanford University, and the Ethereum Foundation (arXiv:2603.28846), have demonstrated the resource feasibility of breaking secp256k1 elliptic curve cryptography using fault-tolerant quantum computation (≤ 1200 logical qubits and ≤ 90 million Toffoli gates). While their work validates this capability via zero-knowledge STARK proofs without disclosing explicit circuits, we provide the continuous operator-theoretic framework that explains the exact physical collapse mechanism underlying their discrete resource results. By modeling cryptographic hardness as a stable, invariant computational manifold, we show that quantum vulnerability is a manifestation of a Birman-Schwinger instability. We prove that, within this model, the introduction of a transverse quantum operator (e.g., Shor's algorithm implemented via Quantum Phase Estimation) forces a resolvent singularity in the classical generator when the resource perturbation parameter crosses a critical threshold (μ_c). We establish a strict Hardness Phase Transition, demonstrating that cryptographic security is equivalent to the point 1 remaining outside the spectrum of the Birman-Schwinger kernel. Furthermore, we formalize zero-knowledge proofs (such as the Groth16-wrapped STARK artifacts published by Babbush et al.) as highly constrained Boolean projectors. We show that these proofs trigger an epistemic spectral collapse via Zeno stabilization, certifying the non-invertible regime without decohering the raw computational state into the public domain. The manuscript includes an exact analytic toy model demonstrating bound-state collapse into the continuum, explicitly mapping the destruction of exponential cryptographic isolation to a polynomial scattering state. This formalization transitions cryptographic failure from a domain of discrete computational estimates to a continuous framework of operator-theoretic necessity.
This paper presents the first formally documented implementation of post-quantum cryptographic infrastructure within a production-grade institutional compliance enforcement system. It addresses a structural vulnerability endemic to the entire regulatory technology industry: every compliance record generated today under RSA or ECC encryption is potentially exposed to "Harvest Now, Decrypt Later" (HNDL) attacks — a documented, operationally active collection strategy confirmed by NSA, CISA, ENISA, and BSI — and will remain so until quantum computers capable of running Shor's algorithm at scale become available, currently projected between 2030 and 2035. Given mandatory regulatory retention periods of 5–30 years under DORA Art.10, GDPR Art.5(e), FinCEN BSA 31 CFR §103.33, Swiss OR Art.958f, and Solvency II, compliance records created today under classical cryptography will still exist — and may be decryptable — within their own legally mandated retention window. This paper documents the complete architectural response: the deployment of CRYSTALS-Kyber-1024 (NIST FIPS 203, 2024) as the primary cryptographic primitive for all compliance ledger operations in the immo.quick Core Machine Law Engine, combined with: A hybrid encryption architecture providing quantum security with full backward compatibility A Merkle Tree Batching scheme reducing post-quantum storage overhead by 99.99% (from 4.67 PB/year to 0.35 TB/year at Tier-1 clearing volumes) A multi-region HSM key hierarchy (EU/CH/US/UK) with Shamir Secret Sharing (3-of-5) and zero-downtime rotation A Zero-Knowledge Proof integration (Groth16, PLONK, Cairo zk-STARK) that resolves the structural contradiction between GDPR Art.17 erasure rights and immutable ledger requirements — by placing zero personal data on the ledger A crypto-agility policy engine enabling algorithm migration without application code changes or audit trail disruption Complete regulatory compliance mappings to DORA, GDPR, BSI TR-02102-1, and NIST FIPS 203 The immo.quick Core platform is presented as the first operational implementation of this architecture across fourteen regulatory frameworks and five institutional sectors (Real Estate, Banking, Insurance, Government, Cloud/FinTech). This paper is a standalone technical specification and supplements the immo.quick Core architecture series (DOI: 10.5281/zenodo.19301212 through 10.5281/zenodo.19457223). It provides the first focused, formally structured academic documentation of CRYSTALS-Kyber-1024 deployment within a deterministic gate enforcement environment with hardware TEE attestation and bi-temporal legal state management. The central argument: Post-Quantum cryptography is not a feature request for 2030. It is a structural prerequisite for any compliance system intended to produce legally defensible evidence chains beyond the quantum threat horizon. The architecture to achieve this exists, is formally specified, and is operationally deployed.
We present DSKAG-IT-SIG, a family of information-theoretic transaction signature schemes that achieve unconditional existential unforgeability under adaptive chosen-message attack by computationally unbounded adversaries. The construction derives per-transaction MAC keys through DSKAG, a deterministic symmetric key agreement protocol requiring no key transmission, no handshake, and no public key infrastructure. We prove (Theorem 1) that the forgery advantage of any unbounded adversary making q queries is at most q * 2^{-128} in standard mode, reducing to the statistical uniformity of DSKAG-derived keys and the pairwise independence of HMAC-SHA256 under a uniform key. We prove (Theorem 2) that cross-domain forgery advantage is at most 2^{-128} + negl(lambda), reducing to the statistical key isolation of DSKAG across policy domains. Both bounds are unconditional and independent of any computational hardness assumption. Standard-mode signatures are 30 bytes, a 97.8% reduction versus Falcon-512 (666 bytes) and compatible with ISO 20022 SWIFT message fields without re-engineering. The NexusKey composite policy digest binds asset class, jurisdiction, KYC level, and chain identity into the key derivation path; policy bypass is cryptographically equivalent to key forgery. A four-layer UltraHonk zero-knowledge proof system (143,802 gates, no trusted setup, 16 KB proof) enables permissionless on-chain compliance verification, deployed on Ethereum Sepolia and Arbitrum Sepolia. Version 2.2. 17 pages, 7 tables. Three independent academic institutions validated the construction: no structural attacks found.
The value of proof-of-work cryptocurrencies critically depends on miners having incentives to follow the protocol. However, the Bitcoin mining protocol proposed by Nakamoto (2008) and implemented in practice is well known not to constitute an equilibrium: Eyal and Sirer (2018) construct a profitable deviation called ``selfish mining'' which relies on strategically delaying disclosure of newly mined blocks rather than publishing them immediately. We propose inertial mining, a novel mining protocol. When miners follow inertial mining, they produce the outcome intended by Nakamoto, i.e., a single longest chain. But unlike the Bitcoin mining protocol, inertial mining constitutes an equilibrium (assuming no miner controls more than half of the mining power). Indeed, neither selfish mining nor any other deviation is profitable. Furthermore, inertial mining only changes miners' behavior in the event of off-path forks, and can be implemented in Bitcoin without any changes to its consensus mechanism or blockchain architecture.
The Legendre Pseudorandom Function (PRF) is a highly efficient cryptographic primitive built upon the Legendre symbol, valued for its low multiplicative complexity in Multi-Party Computation (MPC) and Zero-Knowledge Proof (ZKP) protocols. While its security over prime fields $\mathbb{F}_p$ is well-documented, recent interest has shifted toward instantiations over extension fields $\mathbb{F}_{p^r}$. This paper presents the first comprehensive cryptanalysis of the single-degree Legendre PRF operating over $\mathbb{F}_{p^r}$. First, we analyze polynomial input encoding under a standard passive threat model (sequential additive counter queries). We demonstrate that while the absence of polynomial carry-overs causes an asynchronous "no-carry fracture" that neutralizes classical sliding-window collision attacks, the fracture itself is deterministically periodic. By introducing a novel "Differential Signature" bucketing technique, we prove that an adversary can systematically group fractured sequences by their structural shapes to bypass this defense, recovering the secret key in $\mathcal{O}(U \cdot p^r/M)$ operations, where $U$ is the unicity distance. Second, we evaluate the PRF under an active Chosen-Query threat model. We demonstrate that an adversary can circumvent the additive fracture by evaluating the PRF along a geometric sequence generated by a primitive polynomial. This structure invokes strict multiplicative homomorphism over $\mathbb{F}^*_{p^r}$, permitting a direct generalization of state-of-the-art table collision attacks to extract the key in $\mathcal{O}(p^r/M)$ operations. Finally, we establish the cryptographic boundaries of these attacks, formally proving the necessity of higher-degree key variants ($d \ge 2$) to achieve exponential security against structural reduction in extension fields.
Marc Dordal Carreras, Gloria Christina Heesen, Kohei Kawaguchi
Proof-of-stake deters attacks by keeping validator stake exposed to slashing and depreciation losses. Liquid staking lets operators obtain voting power using pooled stake while reducing their own exposure by selling liquid staking tokens (LSTs) and shifting uncovered slashing losses onto token holders. We study the security implications of this control-exposure wedge and the protocol design problem it creates. Competitive LST pricing can partly deter attack by lowering the resale value of claims when risk rises, but it cannot fully restore deterrence because liquid staking participants do not internalize ETH-wide depreciation losses. A fee-charging protocol prefers the no-attack regime because it maximizes total stake, yet collateral requirements alone do not generally make that outcome unique. Robust security may therefore require additional tools, including permissioned participation, screening or reserve capacity.
Location-based systems that combine encrypted geographic search with zero-knowledge proximity proofs typically treat the two phases as independent. Under an honest-but-curious server, this leaves an authorization provenance gap: once session state is purged, no forensic procedure can attribute a proof to its originating search session, because the proof's public inputs encode no session-identifying information. We formalize this gap as the search-authorized proof (SAP) security notion and show via a concrete audit re-association attack that proof-external mechanisms, where authorization evidence remains outside the proof, cannot prevent forensic misattribution when the same drop parameters recur across sessions. Search-Bound Proximity Proofs (SBPP) realize the SAP requirements without modifying the ZKP circuit: session nonce, Merkle-root result-set commitment, and signed receipt are decomposed into independently auditable components, enabling property-level fault isolation in offline audit. Experiments on synthetic and real-world data (110,776 OpenStreetMap POIs) show sub-millisecond absolute overhead on a 125 ms Groth16 baseline.
Maritime shipping carries over 80% of global trade, yet cold-chain compliance verification forces a choice between disclosing sensitive telemetry and issuing unverifiable declarations. The EU's Digital Product Passport mandate requires verifiable provenance, but maritime IT systems lack a harmonized event model for interoperability. This thesis presents Ocean DPP, integrating EPCIS 2.0, oneM2M, IOTA anchoring, and Groth16 zero-knowledge proofs to verify compliance without revealing sensor data. Merkle-tree batching amortises on-chain cost, and sixteen experiments over 10,000+ events confirm 48 ms baseline latency, sub-10 ms proof verification, 37% scaling improvement, and zero message loss. The results demonstrate that privacy-preserving, standards-compliant DPPs are viable for maritime supply chains.
Blockchain technology faces increasing security threats from post-quantum vulnerabilities, sophisticated cyberattacks, and fragmented cryptographic implementations. This study proposes a comprehensive multi-layer cryptographic framework that integrates Zero-Knowledge Proofs (ZKPs), Homomorphic Encryption (HE), post-quantum algorithms, threshold cryptography, and Secure Multi-Party Computation (SMPC) across data, network, consensus, and application layers to realize a defense-in-depth model. Grounded in the Confidentiality, Integrity, and Availability (CIA) triad and defense-in-depth ethics, the framework is implemented on Hyperledger Fabric v2.5.4 with modern cryptographic libraries and evaluated over 10⁵ transactions, where baseline performance (245 ± 12 ms, 1,250 tx/s) versus the full framework (2,150 ± 78 ms, 168 tx/s) quantifies the overhead of enhanced security. The work contributes a multi-tier framework, a quantum-resilient consensus with Verifiable Delay Functions (VDFs) for 51% attack detection, a standardization roadmap for cross-chain cryptographic substantiation, and practical operations in healthcare, finance, and supply chain setups. Results demonstrate strengthened confidentiality, integrity, and authentication via encrypted computation, Byzantine Fault-Tolerant (BFT) consensus, and threshold multi-signatures, with hybrid classical–Post-Quantum Cryptography (PQC) and mitigation strategies such as off-chain computation and hardware acceleration offsetting computational costs. Unlike fragmented prior efforts, this integrated, governance-elastic blueprint enables quantum-aware, multi-layer security assurance for regulated enterprises without sacrificing decentralization or scalability.
In the context of banking systems increasingly relying on cloud computing platforms, protecting sensitive data while maintaining processing performance is a major challenge. This paper presents and evaluates a cloud banking data processing model that integrates Homomorphic Encryption (HE), Zero-Knowledge Proof (ZKP), and the ORAM protocol to achieve a balance between security and performance. Experiments were conducted on a real Bank Marketing (UCI) dataset with 5000 records, using DSL query operations to calculate the average balance, count high-balance customers, total call duration, and savings deposit acceptance rate. The results show that the combination of HE, ZKP, and ORAM significantly improves security but increases computational cost; however, a suitable configuration can significantly reduce latency while still meeting security requirements. A detailed analysis of the security-performance trade-off provides an important empirical basis for implementing banking data security solutions in the cloud.
We prove that for planted k-SAT instances with k >= 7 at clause density alpha/alpha_s >= 0.21, a positive fraction of variables are frozen directly in the planted model---without requiring transfer from the random model via quiet planting. The expected number of "support clauses" per variable (clauses in which that variable is the unique satisfying literal) exceeds 1 at remarkably low density: alpha/alpha_s ~ 0.20 for k = 7, compared to the random-model freezing threshold at alpha_f/alpha_s ~ 0.90. We prove that the resulting frozen-core structure implies topological disconnection of the solution subgraph across cluster boundaries, with a cycle-robustness argument showing that short cycles in the factor graph cannot quench the supercritical repair cascade. As an immediate corollary, the Hilbert space spanned by satisfying assignments decomposes into orthogonal sectors preserved by any unitary generated by the adjacency matrix---blocking quantum walks, QAOA at all depths, and quantum annealing. We construct a post-quantum commitment scheme whose binding property reduces to the hardness of solving planted k-SAT, provide formal proofs of completeness, soundness, and zero-knowledge, and derive a digital signature scheme with existential unforgeability via the Fiat-Shamir transform. We present a six-vector quantum attack analysis with proved barriers against five algorithmic families. We give concrete parameter recommendations at NIST security levels 1, 3, and 5, and position the scheme within the landscape of SAT-based and CSP-based cryptographic constructions. We prove that the Grover query complexity for breaking the binding property is Omega(2^{fn/2}); empirical cryptanalysis of Glucose and MiniSat CDCL solvers on our exact distribution yields a classical attack cost of 2^{0.234n} operations, enabling concrete parameter selection at NIST security levels 1, 3, and 5. Empirical validation across 100 random seeds at n = 16 confirms complete cluster isolation at every instance tested.
AIGP-Σ (AI Governance Protocol — Sigma) is a post-quantum cryptographic identity and authorization framework designed for autonomous AI agents operating in multi-agent and agentic payment environments. The protocol suite consists of five interconnected specifications: WP-01: Core Protocol — ML-DSA (CRYSTALS-Dilithium) based identity anchoring with STARK zero-knowledge proofs via RISC0, Bitcoin blockchain timestamping, and a cryptographic Kill Switch mechanism for emergency AI halt. WP-02: Kill Switch — Formal specification of the HALT proof system enabling verifiable, tamper-proof shutdown of AI agents without revealing operational state. WP-03: SSL for Agents — A mutual TLS-equivalent handshake protocol adapted for AI agent-to-agent communication, providing forward secrecy and post-quantum resistance. WP-04: Agentic Payments — Authorization layer for autonomous financial transactions executed by AI agents, with cryptographic scope limitation and audit trails. WP-05: Multi-Agent Orchestration — Trust propagation and delegation model for hierarchical multi-agent systems with verifiable credential chains.
This study presents ZK-EHR, a decentralized access control framework designed to enable secure and privacy-preserving sharing of encrypted electronic health records across institutional boundaries. Unlike existing blockchain-based EHR access control systems that expose user identities on-chain or lack cryptographic privacy guarantees, ZK-EHR decouples authorization from identity disclosure by integrating zk-SNARK-based proofs with blockchain smart contracts to verify policy compliance without revealing user roles, affiliations, or credentials. The framework employs three differentiated actor roles—Patient (Data Owner), Doctor (Care Provider), and Researcher (Authorized Analyst)—with distinct policy-driven access workflows, a custom Groth16 zero-knowledge circuit for role-based constraint enforcement, and a modular architecture combining on-chain verification with off-chain encrypted storage via IPFS. Concrete design proposals for access revocation and replay attack prevention are introduced to address operational security requirements. The system was evaluated under multiple operational and adversarial scenarios. Experimental results indicate consistent on-chain verification latency (approximately 390 ms), reliable rejection of tampered submissions, and per-verification gas consumption of 216,631 gas. A comparative analysis against representative baseline systems demonstrates that ZK-EHR uniquely combines identity anonymity, on-chain cryptographic policy enforcement, and auditable encrypted record retrieval. These findings establish the feasibility of zk-SNARK-based access control for decentralized, verifiable, and privacy-aware EHR management.