SECURE DATA STORAGE SYSTEM USING BLOCKCHAIN TECHNOLOGY

Abstract

To enhance the security and privacy of cloud storage, particularly when data is stored as ciphertext, a blockchain-based access control system has been proposed. This system eliminates the need for a trusted third party by combining Ethereum blockchain technology with ciphertext-policy attribute-based encryption (CP-ABE), utilizing a reduced attribute string for more efficient processing. In traditional systems, users rely on a third-party key to access encrypted data, which creates a vulnerability if a malicious actor gains control. However, with our proposed solution, the blockchain ensures a decentralized, immutable ledger for secure access control, preventing any unauthorized intervention. The system operates with three core components, each designed to optimize security and efficiency. Compared to conventional approaches, our method significantly reduces processing costs, encryption, and decryption times, providing a more scalable, reliable, and privacy-preserving cloud storage solution. This innovative design offers a superior alternative to traditional data access models, ensuring enhanced security without compromising performance.

Specification

Description:FIELD OF INVENTION
A secure data storage system using blockchain technology leverages decentralized, immutable ledgers to ensure data integrity, confidentiality, and availability. By utilizing cryptographic techniques and consensus mechanisms, the system protects against unauthorized access, tampering, and data loss. Smart contracts enable automated, transparent data management, while distributed storage ensures redundancy and fault tolerance, enhancing overall security and reliability.
BACKGROUND OF INVENTION
The rapid growth of digital data has raised significant concerns regarding data security, privacy, and integrity. Traditional centralized data storage systems, while widely adopted, face inherent vulnerabilities such as single points of failure, susceptibility to cyber-attacks, and unauthorized access. In these systems, data is stored in a centralized server, which can be compromised, leading to data breaches, loss, or tampering. Additionally, the reliance on intermediaries for data verification introduces delays, inefficiencies, and increased costs. Blockchain technology, with its decentralized, distributed ledger system, offers a promising solution to these challenges. Originally developed for cryptocurrencies, blockchain ensures data integrity and transparency through a consensus mechanism, where all participants in the network validate and agree on data transactions. Each data entry is encrypted and stored in a block, which is then linked to the previous block, forming a chain. Once a block is added to the blockchain, it is immutable, meaning it cannot be altered or deleted, providing robust data protection against tampering.
By decentralizing data storage across multiple nodes, blockchain eliminates the risk of a single point of failure. Moreover, it enables secure data sharing, ensuring that only authorized participants can access and modify the data through cryptographic keys. With the integration of smart contracts, automated and transparent management of data transactions becomes possible, further enhancing security and reducing the need for intermediaries. This approach promises to revolutionize secure data storage, addressing privacy concerns while ensuring greater transparency, reliability, and trust.
The patent application number 201947017126 discloses a blockchain data processing method and apparatus.
The patent application number 201947016412 discloses a blockchain data protection using homomorphic encryption.
The patent application number 202134048775 discloses a semiconductor device and massive data storage system including the same.
The patent application number 202211065908 discloses a blockchain-based system using the cloud of things for clean water data storage.
The patent application number 202341045020 discloses a secure document verification system using blockchain technology in the iot-based cloud environment.
SUMMARY
The Secure Data Storage System using Blockchain Technology provides a decentralized solution to traditional data storage challenges, ensuring enhanced security, privacy, and integrity. Unlike centralized systems, which are vulnerable to data breaches, unauthorized access, and single points of failure, this system utilizes blockchain's distributed ledger technology to store and manage data across multiple nodes in a network. Each data entry is encrypted and stored in a block, forming an immutable chain of records. Once a block is added to the blockchain, it becomes tamper-resistant, ensuring data integrity and protection against unauthorized modifications or deletions. The system employs consensus mechanisms to validate and verify data transactions, ensuring that only authorized participants can access or alter the stored data. This decentralization eliminates the need for intermediaries, reducing the risk of human errors and enhancing the efficiency and reliability of data management. The integration of smart contracts further streamlines data handling by enabling automated, transparent transactions and processes without manual intervention. Additionally, the system leverages cryptographic techniques, such as public and private key pairs, to ensure that data access is restricted to authorized users, enhancing confidentiality. Through its fault-tolerant and secure architecture, the blockchain-based data storage system offers robust protection against data loss, tampering, and cyber-attacks, making it ideal for applications that require high levels of security, such as healthcare, finance, and government sectors. This innovation revolutionizes data storage by providing a secure, transparent, and efficient alternative to traditional centralized systems.
DETAILED DESCRIPTION OF INVENTION
In recent years, with the rapid growth of cloud computing, many individuals and start-up ventures have opted to upload their data to cloud servers. However, much of the data stored in the cloud, such as private medical records and confidential business information, is highly sensitive. To safeguard this data and preserve user privacy, it is typically stored in an encrypted form as ciphertext. Encryption technology ensures better control over who can access the data, providing a security guarantee. However, implementing effective access control for encrypted data remains a challenging task. Ciphertext-policy attribute-based encryption (CP-ABE), first introduced in 2007, associates private keys with specific attribute sets and encrypts data according to defined access policies. In this scheme, users can only decrypt ciphertext if their attribute set aligns with the access policy specified by the data owner. The key generation center plays a critical role in issuing secret keys based on user attributes, allowing data owners to control who can access their information. However, the reliance on a centralized authority introduces the risk of system compromise if the center's power is corrupted. Therefore, a decentralized solution is necessary to mitigate the threat posed by a trusted central authority. While some research and organizations have explored blockchain-based secure access control systems, the field is still in its infancy. Blockchain offers a promising avenue for decentralizing access control without relying on a central authority. This paper proposes an attribute-based encryption scheme using Ethereum blockchain technology to provide decentralized, secure cloud storage. It integrates Ethereum smart contract technology to monitor and track data access behaviors, storing access records on the blockchain network. This solution enables fine-grained access control while ensuring that only authorized users can decrypt data within a specified time period. The proposed system is resilient to various attacks and is tested on the Ethereum test RPC, demonstrating its effectiveness in securing cloud storage and managing access control. Furthermore, the framework is compared with existing solutions to highlight its advantages in decentralization, security, and efficiency.
Centralized Authority and its Risks in Attribute-Based Encryption (ABE)
The current attribute-based encryption (ABE) access control system largely depends on a centralized authority. However, this centralized approach introduces the risk of key leakage, especially if the authority becomes untrustworthy or is deliberately attacked. To mitigate this risk, researchers have explored decentralizing the power of the central authority in ABE systems. This decentralization aims to improve the security and reliability of the system by distributing authority across multiple entities.
Decentralized Solutions to Attribute-Based Encryption Access Control
1. Multi-Authorization Approach: One proposed solution involves a multi-authorization cryptosystem, where multiple authorities assign attributes to users. This reduces the dependency on a single central authority, making the system more robust against failures.
2. Threshold Multi-Authority Systems: Another approach involves a "threshold multi-authority" fuzzy identification technique, which does not rely on a central authority. This enhances security by ensuring that multiple authorities must collaborate to grant access, increasing the overall resilience of the system.
3. Decentralized Attribute-Based Encryption (DABE): A decentralized encryption method, effectively implementing a "multi-authorization" system without a central authority, has been proposed to distribute control while maintaining security.
4. BlendAC for IoT Systems: A decentralized access-control method called "BlendAC" was proposed to ensure secure data access for different services within a large-scale Internet of Things (IoT) system.
5. Blockchain-Based Data Sharing: Blockchain technology can be used to record, maintain, and enforce data-sharing agreements, ensuring secure and transparent access control.
6. Blockchain for Secure Authentication: Blockchain-based systems can enforce fine-grained access control restrictions while ensuring privacy and security during authentication processes.
Combining Blockchain and Access Control Mechanisms
The integration of blockchain technology with access control mechanisms has gained traction in academic research as it effectively addresses trust issues associated with centralized systems. Notable studies have explored:
• Access Control Lists on Blockchain: Blockchain technology is used to store user access control lists, providing a decentralized and tamper-proof method for managing access rights.
• Blockchain in Biomedical and Healthcare Applications: Blockchain is being applied for access control in biomedical and healthcare settings, ensuring secure and efficient management of sensitive data.
• Blockchain for IoT Access Control: Blockchain and smart contracts can manage access control for Internet of Things (IoT) devices, ensuring secure and transparent interactions.
• Secure Cloud Access with Attribute Updates and Revocation: A framework for secure cloud access incorporates dynamic updates to attributes and a revocation policy, demonstrating the potential of blockchain for managing cloud-based access control.
Single Attribute and Access Structure
In this proposed scheme, a single attribute string, denoted as As, is used to represent a collection of attributes such as {at1, at2, ..., atn}. This approach reduces storage requirements and enhances execution efficiency during encryption and decryption processes. For a user set U = {u1, u2, ..., un}, the attribute set As ⊆ 2{u1, u2, ..., un} is considered monotonic, meaning that if a subset of authorized users X is included in As, any superset Y of X will also be part of As. Unauthorized users are those not included in the set As.
Blockchain Technology
Blockchain is a distributed ledger technology used for storing and distributing information securely and transparently. It offers several key advantages over conventional systems: it is tamper-proof, transparent, and auditable. Each block in the blockchain is linked to the previous one, forming an immutable chain. The use of secure hash algorithms, such as SHA-256, ensures the integrity of the data stored in each block. Blockchain technology is increasingly being applied across various sectors, including cloud computing, e-healthcare, and digital document sharing, due to its inherent security and decentralization features.

Figure 1: Blockchain Technology
The proposed model involves four entities: Data User (DU), Blockchain with Smart Contract (SC), Cloud Server, and Data Owner (DO). In this system, the Smart Contract (SC), built on the Ethereum blockchain, plays a critical role in securely storing transaction details such as file IDs, hashes, and encrypted keys. SCs execute the encryption and decryption processes while ensuring that all transactions are recorded on the distributed ledger, making them non-tamperable and non-repudiable. The flow of information between data consumers and data owners remains secure, as shown in Figure 2.

Figure 2: Proposed System Model
System Framework and Functions
The proposed framework follows a series of steps:
1. DO Deploys SC: The Data Owner (DO) deploys a smart contract to the blockchain to save transaction records.
2. Smart Contract Address: The DO stores the contract address on the blockchain.
3. File Metadata Storage: The DO stores the file ID along with the corresponding hash ID.
4. Encrypted File Upload: The DO uploads the encrypted file to the cloud, linking it to the smart contract address.
5. DU Request: The Data User (DU) sends an access request to the DO.
6. Access Time and Period: The DO adds the access time and duration to the DU's request and stores this in the smart contract.
7. Secret Key Storage: The DU's secret key is encrypted and stored within the smart contract.
8. Smart Contract Address Sent: The DO sends the smart contract address to the DU.
9. File Download: The DU downloads the encrypted file from the cloud.
10. Secret Key Retrieval: The DU retrieves the encrypted secret key from the smart contract.
Setup Phase
In the Setup Phase, the DO executes a setup algorithm with a predefined set of attributes (U) and parameters (k) as inputs. This results in the generation of a public key and a master key (MSk). Simultaneously, the Ethereum smart contract "save record" is deployed.


Key Generation Phase
In the Key Generation Phase, the DU sends an access request to the DO, which assigns the access time and duration. The DU generates a secret key (SK), and the encrypted key is stored in the smart contract.
• Secret Key:

Data Encryption
The DO performs encryption using an attribute string (Ati), the plaintext message (M), and public parameters. This results in a ciphertext (CT):
• Ciphertext (CT):


Data Decryption
When the DU receives the request to access the encrypted data from the cloud, the data is in an encrypted form. To decrypt the data, the DU applies a decryption algorithm using the attribute string (As), the ciphertext (CT), and the secret key (SK):
• Decryption Formula:

where the decryption process recovers the original message (M) from the ciphertext.
Performance Evaluation and Analysis
The performance of the proposed scheme is evaluated on an experimental platform with the following configuration: an Intel(R) Core(TM)2 Duo CPU E8350@2.85GHz processor, 8 GB RAM, and operating systems Windows 10 and Ubuntu 18.04 LTS. The Smart Contract (SC) is written in Solidity. All evaluations are repeated 50 times, and the average value is considered. For the experiment, ten files of varying sizes (in KBs) are examined. The calculation overhead, including key generation, encryption, ciphertext share construction, and other processes, is compared with the scheme presented. Figure-3 illustrates the comparison of computational overhead. The proposed scheme requires less time due to its reduced attribute length concept, outperforming other systems in terms of time efficiency. The encryption and decryption times are plotted in Figure-4 and Figure-5, respectively. Table-1 presents a comparison of the proposed scheme with on different parameters.

Figure 3: Plot for comparison of Computation overhead

Figure 4: Plot for comparison of Encryption Time

Figure 5: Plot for comparison of Decryption Time
A. Security Analysis
Case 1: Cloud Storage of Sensitive Information
In the proposed architecture, sensitive data stored on the cloud is fully protected. Data security is a major concern for cloud-based service users, especially when operating over unstable networks that increase the risk of hacking and data leakage. In this model, all data is encrypted, and decryption requires access to the smart contract along with the blockchain transaction ID. Each authorized user is assigned a unique random value (denoted as r) from Zp. If an unauthorized user fails to meet the access policy defined by the CO, the mapping e(g,g)rs cannot be generated during the decryption process, preventing the unauthorized user from recovering the original message M.
Case 2: Protection Against Collision Attacks
The proposed model also protects against collision attacks. If a malicious user gains access to the system and attempts to interact with another user, there is a risk of exchanging confidential key characteristics. The system recalculates and verifies the hash data against the current data. If the hash values (denoted as h and h′) match, the data is confirmed to be unaltered; otherwise, it indicates tampering. This approach significantly reduces the risk of collision-based attacks, ensuring the integrity of the data.
Case 3: Audit Record Generation
The proposed methodology ensures accurate and comprehensive generation of audit records. By integrating blockchain technology into the data-sharing strategy, a reliable access log is generated each time a user requests access. This log is immutable, ensuring that it cannot be altered. Both the data owner and the data user can verify the stored records in accordance with the access policy and request. The use of blockchain guarantees the auditability of the process, providing transparency and accountability.
Table 1: Performance and Security Analysis Comparison

This study proposes a framework that leverages blockchain for secure cloud-based storage access. By utilizing Ethereum's smart contract technology, transactions are automatically recorded on the blockchain. To ensure complete access control, an attribute-based cryptography method with a simplified attribute string is employed. The use of blockchain in the proposed framework eliminates the reliance on a central authority for distributing keys, thereby reducing vulnerability to attacks. Communication between the Data Owner (DO) node and the Data User (DU) node is only possible through the distributed access control mechanism. Experimental results demonstrate that, due to the reduced attribute string concept, the computational cost of accessing data is relatively low. However, further research is required. Additionally, while the current framework is built on cloud storage infrastructure, future work will explore the integration of decentralized storage systems like the InterPlanetary File System (IPFS). The implementation will also be tested in real-world environments.
DETAILED DESCRIPTION OF DIAGRAM
Figure 1: Blockchain Technology
Figure 2: Proposed System Model
Figure 3: Plot for comparison of Computation overhead
Figure 4: Plot for comparison of Encryption Time
Figure 5: Plot for comparison of Decryption Time , Claims:1. Secure Data Storage System Using Blockchain Technology claims that Eliminates reliance on a central authority for key distribution, ensuring resistance to single points of failure and enhancing overall system security.
2. Blockchain ensures that all transactions, including access requests and data modifications, are securely recorded and cannot be tampered with or altered.
3. Utilizes attribute-based encryption with a simplified attribute string to provide fine-grained and efficient access control for authorized users.
4. Smart contracts on Ethereum autonomously log all access and storage transactions, ensuring transparency and auditability.
5. Implements secure cryptographic mechanisms to prevent unauthorized users from forging or colliding attribute keys for data access.
6. The simplified attribute string mechanism minimizes encryption and decryption costs, enabling faster and more efficient data access.
7. Protects sensitive information from brute-force, hopping, and traditional cryptographic attacks, as well as mitigating potential collision-based attacks.
8. Blockchain technology ensures reliable and tamper-proof access logs, enabling data owners and users to verify all interactions and transactions.
9. The system can be integrated with decentralized storage solutions like IPFS for enhanced scalability, reliability, and data redundancy.
10. The design is adaptable for implementation in real-world environments, making it a robust foundation for secure and scalable data storage solutions.