In a rapidly digitalizing world, identity verification has become the cornerstone of secure online interaction. Traditional authentication models, which depend on centralized authorities and password-based systems, are increasingly vulnerable to breaches, identity theft, and data manipulation. Blockchain-backed identity systems offer a promising alternative by decentralizing trust, ensuring immutability, and empowering users with self-sovereign control over their credentials. This review explores how blockchain technology enhances authentication reliability through decentralization, cryptographic assurance, and automation. The paper first examines the fundamentals of blockchain-based identity management, including decentralized identifiers (DIDs), verifiable credentials (VCs), and smart contracts that automate credential verification and revocation. It then presents the architectural components of blockchain identity systems, highlighting how cryptographic hashing, distributed consensus, and off-chain storage combine to create secure yet compliant authentication workflows. The analysis demonstrates that blockchain-backed identity frameworks significantly improve authentication reliability by removing single points of failure, enhancing data integrity, and enabling privacy-preserving verification through mechanisms like zero-knowledge proofs. Comparative evaluation with traditional systems reveals that blockchain ensures superior resilience, transparency, and user control, albeit with challenges in scalability, interoperability, and key management.
There is a large amount of redundant data among users of cloud storage services. Client-side deduplication helps reduce the cost for service providers by avoiding repeated uploads and storage. However, this technique brings new security risks. Malicious users may use illegally obtained deduplication tags, such as file fingerprints, to fake ownership of other users’ files. Proof of Ownership (PoW) can require users to prove they have the full file, but existing methods are inefficient. They often need multiple rounds of interaction or complex computation over the whole file. As a result, the verification time increases with file size. To solve this problem, we propose a non-interactive PoW scheme based on zk-STARK. The system selects a number of challenge blocks that meet cryptographic security. It uses arithmetic circuits to encode block selection, hash computation, and the correctness of accumulators. Users only need to generate a zero-knowledge proof on these blocks. This allows them to prove they own the full file without revealing its content. The verification time does not depend on file size and appears near-constant in practice. In tests on files from 64 MB to 1 GB, our scheme is 1.2 to 46 times faster than existing methods. Security analysis shows that only a small number of blocks need to be verified. Even if an attacker knows 90% of the file, the chance of forgery is still lower than 2 − 80 . This scheme provides an efficient and practical solution for deduplication in cloud storage with strong privacy protection.
Cloud computing has emerged as the dominant platform for contemporary data management and service provision. However, its centralized nature poses significant risks to security, privacy, and trust. Distributed systems can enhance data integrity and auditability by incorporating blockchain technology, which offers a decentralized and tamper-resistant approach. Nevertheless, the inherent transparency of blockchain conflicts with the confidentiality requirements of cloud environments. This review paper analyzes existing studies on privacy-preserving blockchain architectures designed to secure cloud-based information systems. A systematic literature review methodology was adopted, examining forty-eight peer-reviewed studies published between 2018 and 2024. The findings reveal that researchers have explored approaches such as encryption, zero-knowledge proofs, homomorphic encryption, and hybrid on/off-chain models to balance transparency and privacy. Scalability, interoperability, and regulatory compliance remain key challenges, particularly in permissioned blockchains, which nevertheless offer advantages in governance and compliance. The study identifies research gaps and future directions, including the development of common privacy frameworks, integration of confidential computing, and establishment of standardized evaluation metrics. Overall, privacy-sensitive blockchain architectures hold strong potential for creating trustworthy and secure cloud systems.
Zero-knowledge proofs (ZKPs) enable a prover to convince a verifier of knowledge of a secret without revealing it. The ZKP for the square-root problem has many applications in network and cloud security, such as user authentication and privacy-preserving cloud storage auditing. Classical protocols for the quadratic residuosity (square-root) relation require multiple iterations to reach negligible soundness error, incurring latency and communication costs that are critical in cloud settings. This paper proposes a new single-round zero-knowledge proof (SR-ZKP) for the square-root problem that achieves the same soundness as iterative schemes by increasing the challenge length. The protocol requires only one execution of a 4-message protocol (request, commit, challenge, response) and can be transformed into a one-message non-interactive ZKP via the Fiat–Shamir heuristic. The completeness, soundness, and zero-knowledge properties of the proposed scheme are formally proven. The results of this study show that the proposed protocol can achieve approximately \(97\%\) reduction in communication overhead and latency, when compared to an 80-round iterative ZKPs with RSA modulus n of size 2048 bits. This provides a substantial advantage for cloud applications.
Hassan Raza, Tsendayush Erdenetsogt, Muhammad Mohsin Kabeer, Muhammad Arsalan Aslam · 5 authors
The block chain technology has become a potential solution to improving security, privacy, and trust on contemporary data management systems. Conventional centralized systems are easily breached, tampered with and unauthorized access makes it necessary to have decentralized systems that cannot easily be tampered with. Block chain offers immutability, transparency, and cryptographic security and smart contracts offer automated access control and auditing. Sensitive information is safeguarded using privacy-saving methods, such as encryption, a zero-knowledge proof, and decentralized identity schemes. Scalability and collaboration are further increased with integration with cloud and big data systems. This review identifies the uses of Block chain, challenges and future research direction, which shows that Block chain is capable of changing the way secure and privacy-conscious data management is achieved.
Zero-knowledge proofs (ZKPs) have evolved from foundational interactive proof systems to highly efficient, scalable, and trusted-setup-free constructions powering today’s privacy-preserving and blockchain applications. The field began with the seminal works of Goldwasser, Micali, and Rackoff (GMR) and Goldreich, Micali, Wigderson (GMW) in the 1980s, which introduced interactive proofs, knowledge complexity, and showed that all NP languages admit zero-knowledge proofs. The 1990s brought non-interactive ZK (NIZK) via the CRS model (Blum–Feldman–Micali) and practical sigma-protocols like Schnorr proofs, establishing foundational tools still used today. From the 2000s through early 2010s, research integrated pairings, PCPs, and cryptographic soundness, culminating in pairing-based NIZKs and early succinct argument systems. The SNARK revolution accelerated with QAP-based zk-SNARKs (Gennaro–Gentry–Parno), practical implementations like Pinocchio and libsnark, and the highly efficient Groth16 proving system that became a blockchain standard. Since 2018, the field has shifted toward transparent, universal, and post-quantum-secure systems. Innovations include Bulletproofs (short proofs without trusted setup), zk-STARKs (scalable and PQ-secure), PLONK (universal/updatable setup), and Halo/Halo2 enabling recursive proofs without trusted setup. These advances underpin modern Zcash deployments, zk-rollups, and privacy-preserving scaling systems across Web3. Overall, the ZKP landscape has progressed from theoretical constructs to practical, scalable, and secure systems central to modern cryptography and decentralized computation.
In today's digital age, cloud storage and computing have become indispensable. Resource-constrained clients such as individuals and small organisations increasingly rely on powerful servers to store, manage and process their data. However, outsourcing data to external servers leads to significant privacy concerns, particularly when dealing with sensitive information such as medical records, financial transactions, or personal data. Fully homomorphic encryption (FHE) is a cryptographic technique that allows computation over encrypted data. In secure outsourcing with FHE, a client sends encrypted data to a server, which can perform requested computations without accessing the original data. The server returns the resulting ciphertexts, which the client can decrypt to obtain the final output. Despite its strong privacy guarantees, the practical adoption of FHE is limited by two main challenges: efficiency, which arises from the substantial performance overhead of FHE; and integrity, which stems from the lack of mechanisms to verify the correctness of the outsourced computation. In this thesis, we contribute to addressing these challenges in three aspects. First, we optimise oblivious algorithms for use in FHE, achieving improvements in key performance metrics and accelerating both bootstrapping and a range of applications. Second, we build efficient privacy-preserving information systems based on FHE. These include (i) two private machine learning protocols, the k-nearest neighbour algorithm and decision tree evaluation, (ii) SQUID, a secure system for storing and analysing genotype-phenotype data, and (iii) a protocol for securely delegating zero-knowledge proof generation. Third, we construct verifiable secure delegation of computation through FHE techniques. We provide the notion of blind proofs to provide integrity guarantees and demonstrate its practicality using blind zkSNARKs, a concrete instantiation of blind proofs.
Nov 28, 2025·2025 IEEE 1st International Conference on Smart Innovations in Systems, Infrastructure, Mechanical, Power, AI and Computing Technologies (SISIMPACT)
The proposed privacy-preserving identity management framework in this research is the combination of blockchain technology, zero-knowledge proofs, and adaptive sharding, which improves security, scalability and regulatory compliance and cybersecurity system. In contrast to current blockchain-based identity mechanisms, the presented mechanism involves encryption of identity attributes and distributes them on dynamic permissioned shards with the ability to selectively disclose identity information without leaking sensitive information. Comparison to Sovrin SSI, uPort and Civic show off impressive results, with a$33-63$percent increase in the transaction rate, 32 percent reduction in the duration of verification and 27 percent less time to generate the proofs. Compliance is achieved by reducing the storage overhead during which the immutability is preserved with chameleon hash-based redaction. There is a huge probability of leakage of privacy and efficiency of the consensus is 97 percent, so identity operations are sound and resistant to tampering. The architecture even makes it possible to have safe cross-domain authentication within heterogeneous environment. These results reassure that the framework will provide secure, efficient, and privacy-compliant identity management and thus will be very useful in enterprise, government, and IoT-based cybersecurity environments.
Neeraj Purushotham, Mallepula Likhitha, Y Sai Pragathi, C RaviKiran · 5 authors
Secure and verifiable cloud storage auditing is a significant issue of concern with identity-based systems, especially against malicious auditors and forged proof attacks. In this paper, the enhanced identity-based public audit protocol has been enhanced with blockchain-supported federated trust and quantum resilient cryptographic priming. The suggested Quantum-Resistant Federated Identity-Based Auditing (QFIBA) scheme does not have a single-point dependency on the PKG and proposes a lattice-based identity encryption that ensures post-quantum security. The proposed system implements privacy-preserving audits via zero-knowledge verification made using zk-SNARK without exposing user metadata. The results of experiments carried out on the JPBC and CRYSTALS-Dilithium schemes show that the tag generation cost is reduced by 19.6 per cent, the proof generation overhead is reduced by 14.2 per cent and the verification rate is 12.8 times faster than the better IBPA scheme with the same audit soundness and forgery resistance. Security guarantees: It has been shown that QFIBA is secure to the CDH and LWE assumptions. Such findings confirm the practical effectiveness of the scheme and its resilience to the future cloud ecosystems where federated trust and quantum resilience is needed.
T J E N N I N G, Kalokhe Omkar Nanabhau, Takale Ram Arjun, Borge Akash Sandip
The proliferation of digital documents and academic credentials in today's interconnected world has created both opportunities and vulnerabilities. Traditional certificate issuance and storage mechanisms are highly susceptible to forgery, duplication, and unauthorized manipulation, undermining the trustworthiness of academic and professional qualifications. To address these challenges, this research proposes a blockchain-based certificate generation and verification system that ensures transparency, immutability, and trust across stakeholders. Leveraging distributed ledger technology, the system securely records certificate metadata and unique identifiers, enabling real-time, tamper-proof validation without reliance on intermediaries. The architecture integrates modern web technologies such as Next.js for frontend and backend services, MongoDB for scalable storage, JWT for authentication, and cryptographic techniques including bcrypt for enhanced security. Additionally, smart contracts deployed on Ethereum/Ganache enable decentralized storage and validation, while certificate data is simultaneously linked with non-fungible tokens (NFTs) to provide verifiable ownership and authenticity. This integration not only eliminates certificate fraud but also facilitates seamless verification across institutions, employers, and regulatory authorities. By combining blockchain's decentralized security with user-friendly web applications, the proposed approach aims to create a globally interoperable, cost-effective, and future-ready framework for academic and professional certification systems.
On the other hand, the buzz around modern technology like decentralized identity management (DCI) is somewhat frozen in time on a blockchain to ensure its security and efficiency for cross-border digital services. The traditional way of identity management relies on a centralized authority and, therefore are very vulnerable to data breaches, extremely inefficient, and continuously quite hard to control. Concepts of self-sovereignty such as self-sovereign identity, decentralized identifiers, and verifiable credentials drive the DCI evolving way where persons can control their own personal data and usually share it selectively by themselves without the mediation of any third party. Cryptographic techniques such as zero-knowledge proof, are highly relevant to privacy and security, whereas a non-repudiable blockchain ledger is the security and necessarily provides auditability, ensuring authentication and non-repudiation. This paper examines how a blockchain Digitalized decentralized identity can serve to resolve some pertinent issues with regard to regulatory compliance in cross-border digital transactions, therefore thwarting identityrelated frauds and facilitating their international interoperability. The practical cases would showcase leaps in technology speed, one trust of the user, and regulatory harmonization with regard to the travel biometric credential systems being currently exhibited with reference to the e-Residency program in Estonia. Scalability and key management, though still some issues linger, the trend shows that upcoming innovations in the blockchain protocol-game and in the regulatory framework contribute to DCI being one of the major pillars of the trusted user-centric secure digital identity solution of the future global economy.
In this paper, we presented BlockShare, a blockchain-based system developed to facilitate privacy-preserving data sharing across decentralized networks. The proposed system enables users to retain control over their sensitive data while enabling secure, verifiable sharing with authorized parties.We implemented an authenticated data structure (ADS) to support decentralized verification and utilized zero-knowledge proof mechanisms to validate conditions without exposing the underlying data. Experimental analysis demonstrated that BlockShare performs efficiently in constructing data structures, generating proofs, and verifying them with minimal computational overhead. The platform successfully reduced privacy risks and enhanced trust in cross-organization data exchanges.
Decentralized file systems (DFS) offer secure and transparent and resilient data storage through the integration of peer-to-peer storage protocols and blockchain technologies. Such systems are, nevertheless, vulnerable to a range of threats to security at an application, smart-contract, or network level. We present a profound discussion of the weaknesses of a DFS developed based on IPFS as a file-storing engine, Ethereum as metadata storage, and MetaMask as authentication in this paper. With a combination of tools of superior quality in security-related analyses, like Slither, MythX, and Metasploit, we model attack-related situations in the form of reentrancy, content poisoning, and Sybil, as well as phishing. The evidence highlights the main threats, with chief ones being contract-logic defects, file-integrity breaks and session socialists. We suggest the relevant countermeasures, including the best practices in smart-contract writing, cryptographic assurance of content identifiers (CIDs), strong session management, and defences against nodes. The findings provide a security benchmark to system developers and researchers keen on enhancing the robustness of decentralized systems of storage.
Farhad Asgarov, Fatih Said Duran, Namig Samadov, Şerif Bahtıyar
Cite this article as: F. Asgarov, F. S. Duran, N. Samadov and Ş. Bahtiyar, “Blockchain based ownership and DNS configuration with ethereum rollups,”Electrica, 25, 0051, doi: 10.5152/electrica.2025.25005.
Academic certificate fraud has become a significant concern for universities, institutions, and employers worldwide, as it directly affects the credibility and reliability of academic qualifications. Conventional methods for verifying certificates are largely manual, tedious, and prone to errors or manipulation, as they lack a centralized and tamper-resistant validation mechanism. The emergence of blockchain technology offers a revolutionary solution by enabling decentralized and immutable storage of certificate data, ensuring trust and transparency. This paper proposes and implements a blockchain-based academic certificate authentication framework that utilizes Ethereum smart contracts to securely record and manage certificate metadata. Additionally, the InterPlanetary File System (IPFS) is integrated to facilitate decentralized and permanent storage of certificate files. The proposed system ensures that certificates are verified transparently, instantly, and without reliance on third-party intermediaries, thus streamlining the overall verification process. It empowers academic institutions to issue certificates securely while enabling verifiers to authenticate them efficiently, reducing administrative burden and minimizing the risk of document forgery. The results of the implementation demonstrate superior data integrity, operational performance, and user trust when compared to traditional verification approaches. This paper presents the existing challenges in certificate validation, details the methodology and design of the system, and provides experimental evaluations to establish its effectiveness for secure academic certificate verification.
In an age where knowledge is power and credentials are the currency of trust, securing academic qualifications while preserving individual privacy has become paramount. Traditional verification methods are costly, slow, and prone to fraud, and centralized digital systems risk exposing sensitive personal data. To address these challenges, we propose a novel framework the Blockchain Academic Credential Interoperability Protocol (BACIP) - that leverages blockchain technology and zero-knowledge proofs (ZKPs). BACIP integrates smart contracts and a dual-blockchain architecture with privacy-preserving ZKP circuits (implemented via Circom/SnarkJS) to automate issuance, storage, and cross-border verification of educational credentials. Our methodology combines on-chain integrity (via Ethereum/Polygon smart contracts) with off-chain confidentiality (using AES encryption and IPFS storage) and self-sovereign identities (DIDs). The distinguishing innovation of BACIP is the seamless integration of ZKPs throughout the credential lifecycle, enabling verifiers to validate specific academic attributes-such as degree completion or GPA-without accessing or exposing any underlying personal data. This approach ensures cryptographic trust while upholding strict privacy standards. Initial results demonstrate a considerably well proof success rate, improved compliance with data protection regulations such as GDPR, and a significant reduction in on-chain computational load. By uniting the transparency of blockchain with the confidentiality of zero-knowledge techniques, BACIP offers a scalable and interoperable framework for secure academic credentialing. Institutions and employers benefit from faster, automated verification workflows, while learners maintain full control over their digital identities and credentials. Ultimately, BACIP paves the way for trustworthy, efficient, and privacy-respecting academic mobility across borders and platforms.
Abstract Organizations increasingly require secure document management with integrity guarantees beyond traditional audit logs, particularly in regulated industries where external accountability is critical. While blockchain technologies provide strong tamper-detection, they present significant enterprise adoption challenges including cost volatility, low throughput, and unpredictable operational expenses. This thesis proposes a Centralized Ledger System (CLS) that provides blockchain-inspired integrity verification through self-hosted architecture without external dependencies. The system implements a three-phase entry lifecycle, signature collection and verification, supporting multi-party transactions with asynchronous workflows. A multi-ledger architecture enables organizational segregation of business domains while maintaining referential integrity. Key contributions include automated receipt generation for independent verification, selective payload erasure preserving cryptographic validation, entry linking for audit simplification, and integration of security services with two-factor authentication and key management. The modular design enables flexible deployment while maintaining cryptographic guarantees equivalent to blockchain systems. The solution addresses the gap between traditional audit systems and distributed ledgers by providing cost-predictable, vendor-independent functionality that integrates into existing workflows without specialized blockchain expertise.
The Verification and Validation of Certificate Using Blockchain system is designed to provide a secure, transparent, and tamper-proof mechanism for issuing and verifying educational and professional certificates. Traditional verification methods are often prone to forgery, delays, and administrative inefficiencies due to centralized databases and manual validation. This system leverages blockchain technology to store certificate data in an immutable distributed ledger, ensuring authenticity and preventing manipulation. Additionally, the integration of the InterPlanetary File System (IPFS) provides decentralized, lowcost storage for certificates, while an Android-based interface simplifies issuance and verification processes. By enabling decentralized trust, rapid verification, and cross-border accessibility, this system enhances transparency, reduces fraudulent activities, and establishes a reliable digital framework for secure credential management
Amol Murgai, M. Vijay Bhasker Reddy, M. P. Vani, Prof. Supriya Jagtap · 6 authors
Cloud edge convergence is enabling real time personalized learning but come with security and trust issues. Centralized models cause single points of failure, and lack transparency. This paper proposes a framework for decentralized access control and auditability of blockchains and tamper resistance to try to make smart contracts work well. Prototype using Ethereum and IPFS: low latency in authorization, better discretion is achieved comparing with the centralized approaches. This paper presents a blockchain technology framework that will facilitate secure data sharing process in cloud-edge learning networks. The framework has smart contracts that enforce the dynamic policy of access to provide auditable records of all data transactions. A prototype implementation that is tested in a simulated federated learning scenario shows how the system can deal with access decisions with low latency and data integrity and audit beyond. These findings indicate that blockchain can be one of the possible ways of moving to decentralized, policybased information cooperation in the education sector, where information protection and institutional trust are critical.
Secure authentication along with malware detection are very important steps in modern cloud or IoT environment, with, privacy, accountability, and resilience against advanced threats. The present day anonymous authentication protocols reportedly have a high cryptographic overhead, low traceability, or static privacy mechanisms, while the current IoT malware forensic approaches happen to suffer from gradient leakage, low adaptability to zero day attacks, and slow resilience. This paper presents a comprehensive multi model framework combining five novel methods. The Dual Ledger Accountability Embedded Authentication (DLAA) model combines a primary blockchain with a secondary lightweight audit ledger and zero knowledge proofs, enabling revocable accountability without identity disclosure. The Layered Privacy Gradient Synthesis (LPGS) network applies adaptive differential privacy through learned gradient perturbations, balancing anonymity with service utility. The Quantum Inspired Entropy Guided Authentication Matrix (QEAM) replaces the key exchange with entropy driven, quantum inspired encoding, enabling faster keyless authentication. For IoT forensics, the Federated Swarm Vector Autoencoder Forensics (FSVAF) framework uses swarm optimized federated learning to detect anomalies in compressed latent space, reducing gradient leakage and improving zero day detection possibilities. The Temporal Hybrid Graph Reasoning Engine (THGRE) fuses symbolic rules with neural inference over evolving knowledge graphs for quick malware traceback. The experimental output reveals that the authentication time is reduced by 38%, with 94% malware detection accuracy in adaptive attack conditions, and is able to resolve forensics up to 67% more rapidly than previous static approaches with significantly reduced overhead. This framework collectively enhance privacy, accountability, scalability, and forensic dependability, making it efficient solution for next generation cloud and IoT ecosystems.
In today’s educational landscape the proliferation of forged or manipulated student certificates undermines trust in academic credentials. This paper presents a blockchain-based solution for issuing and validating student certificates by recording cryptographic hashes of credential metadata on a distributed ledger and optionally storing full certificate files off-chain. Smart contracts govern issuance and verification, eliminating intermediaries and enabling instant, tamper-proof checks. The proposed system enhances transparency and integrity, reduces verification overhead, and empowers students and employers with direct access to credential authenticity. Challenges such as scalability, privacy of student data, cost of transactions, and institutional adoption are discussed with suggestions for future work.
Polygon Chain Development Kit (CDK) Validium is a Layer 2 blockchain scaling solution that processes transactions off-chain. It uses Polygon’s distinctive approach to Zero-Knowledge Proofs (ZKPs) implemented within their Zero-Knowledge Ethereum Virtual Machine (zkEVM). A key factor in its successful deployment is robustness, ensuring that users can trust their transactions will be processed accurately and promptly. This research concerns developing robust validation methodologies and comprehensive testing strategies targeting the “double-spending” problem within Polygon CDK Validium. We indicate theoretical scenarios where double-spending vulnerabilities could arise in Polygon CDK Validium by identifying how execution errors can combine with a specific category of flawed constraints to create vulnerabilities. When combined with what we classify as Invalid PIL Constraints For EVM Specification Vulnerabilities (IPCFESV), these errors can trigger problematic behaviours. We further illustrate how erroneous behaviour resulting from IPCFESV can lead to cascading involvement in withdrawal operations resulting in irreversible cross-layer double-spending. We also illustrate how a protocol anti-censorship mechanism bypasses standard validation checks, thereby intensifying reliance on constraint correctness. We then propose ways to determine the correct behaviour. We propose a method to utilise Polygon’s integration testing framework for generating execution traces for de-facto ERC-20 fungible token standard. The outcomes of this study will form the foundational basis for the subsequent development of practical testing and verification methods for Polygon CDK Validium. Implementation and empirical validation remain as future work.
Luiz Eduardo Folly de Campos, Reinaldo Cézar de Morais Gomes
Trust on the internet is an essential pillar for online interactions, and blockchain technologies offer a new paradigm of trust based on data integrity and decentralization, enabling innovative solutions such as theWeb3 applications. This paper presents the experimental infrastructure for blockchain research and development currently being built within the ILIADA project at RNP, and its use for the development of new Web3 applications.
Cloud infrastructure refers to the dynamic provisioning of computing resources over the internet, enabling scalable and flexible enterprise operations. However, such environments face significant security challenges, particularly in access management. Cloud infrastructure delivers scalable computing resources, yet traditional Identity and Access Management (IAM) mechanisms face challenges such as centralized control, misconfigurations, and limited auditability. This study addresses these challenges by proposing a Hyperledger Fabric-based decentralized access control framework integrated with Amazon Web Services (AWS) for healthcare data security. The framework employs Zero Knowledge Proof (ZKP) for identity validation, Ciphertext Policy Attribute Based Encryption (CP- ABE) with Proxy Re-Encryption (PRE) for fine-grained data access, and machine learning driven anomaly detection for continuous monitoring. Experimental evaluation achieved throughput of 15000 transactions per second, latency of 350 milliseconds, privacy preservation up to 99.1 percent, and anomaly detection accuracy of 99.63 percent, surpassing prior models significantly. Storage analysis demonstrated predictable scalability with encrypted medical records up to 20 MB, while token revocation time remained within 1.9 seconds under network stress. The results confirm that blockchain-based access control enhances security, privacy, and auditability while maintaining operational efficiency. This research establishes a scalable and tamper-resistant model for secure healthcare data management in cloud environments.