Blockchain for Secure Cloud Storage

Objective:

To develop a secure, decentralized cloud storage system using blockchain technology that ensures data privacy, integrity, and availability while eliminating reliance on central storage providers and reducing the risks associated with data breaches and unauthorized access.

Key Features:

Decentralized Data Storage – Data is fragmented and distributed across a network of nodes, rather than being stored on a centralized server, ensuring better security and fault tolerance.

Data Encryption & Privacy – Data is encrypted before being stored, ensuring that only authorized users can access it, with decryption keys managed securely.

Blockchain-Based File Integrity – Files are hashed, and their hashes are stored on the blockchain, ensuring that the integrity of stored data can be verified and cannot be tampered with.

Smart Contracts for Access Control – Smart contracts define and enforce who can access the stored data and under what conditions, automating access management.

Redundancy and Fault Tolerance – Since data is distributed across multiple nodes, the system ensures that even if some nodes go offline, data remains accessible.

Transparent Audit Trails – Blockchain provides an immutable, transparent record of who accessed the data and when, ensuring accountability.

File Sharing and Collaboration – Securely share files with other users, while maintaining control over access permissions via blockchain-based smart contracts.

Technologies Used:

Blockchain Platform: Ethereum / IPFS / Filecoin / Storj / Hyperledger Fabric

Smart Contracts: Solidity (for automating access control and data sharing rules)

Encryption Algorithms: AES-256 (for file encryption), RSA (for secure key management)

Distributed Storage Networks: IPFS (InterPlanetary File System) / Filecoin / Storj (decentralized file storage)

Frontend: React.js / Vue.js (for user interface to upload and manage files)

Backend: Node.js / Express.js

Storage: IPFS or other decentralized storage networks for storing encrypted data

Consensus Mechanism: Proof-of-Work (PoW) / Proof-of-Stake (PoS) for validating transactions and data integrity

How It Works:

File Upload and Encryption:

When a user uploads a file to the cloud storage system, the file is first encrypted locally. Only the user holds the decryption key. The encrypted file is then fragmented and distributed across a decentralized network of nodes.

Blockchain Record Creation:

The cryptographic hash of the file (representing the file’s integrity) is recorded on the blockchain. This ensures that any attempt to tamper with the file can be detected by comparing the hash.

Data Distribution and Redundancy:

The encrypted file is split into smaller chunks and distributed across multiple storage nodes. Each node stores a piece of the file, ensuring redundancy and fault tolerance.

Access Control via Smart Contracts:

Smart contracts define and enforce access control policies. If a user wishes to access a file, they need to meet the smart contract's conditions (e.g., permissions or payment). The contract verifies the user’s credentials and grants access if valid.

Audit Trail on Blockchain:

Each access to the file (such as reading, downloading, or sharing) is recorded on the blockchain, creating a transparent and immutable audit trail. This ensures accountability and traceability of who accessed the data.

Data Retrieval and Decryption:

When a user requests the file, the system retrieves the fragmented pieces from the storage network, reassembles them, and provides the user with access. The file is decrypted using the user's private key.

Benefits:

Enhanced Security:

By encrypting files before storing them on decentralized nodes and recording hashes on the blockchain, the system provides superior security and protection against data breaches or unauthorized access.

Data Integrity:

Blockchain guarantees that files cannot be tampered with. Any attempt to modify the data will result in a mismatch of hashes, signaling potential tampering.

Decentralization & Redundancy:

Unlike centralized cloud storage systems, blockchain-based cloud storage reduces the risk of single points of failure. Data is distributed across multiple nodes, ensuring continuous availability and fault tolerance.

Privacy & Control:

Users have full control over their data and access permissions. Data privacy is maintained through strong encryption, and smart contracts automate access management without the need for intermediaries.

Cost-Efficiency:

Decentralized storage reduces the reliance on centralized cloud providers, potentially lowering storage costs by utilizing unused storage resources from individuals or organizations within the network.

Transparency & Accountability:

Blockchain provides a transparent, immutable audit trail of all interactions with stored data, offering full traceability and accountability for data access and modifications.

Collaboration & Sharing:

Secure and controlled file sharing is enabled via blockchain-based access control, making it easier for users to collaborate without compromising on security.