Cloud storage is one of the most important technologies used for storing and managing large amounts of digital data in modern computing environments. With the rapid increase in data generation, centralized cloud storage systems are widely adopted by individuals and organizations due to their convenience and accessibility. However, these traditional systems suffer from several major limitations, including data breaches, privacy leakage, single points of failure, unauthorized access, and dependence on third-party service providers. If the central server is compromised, attackers may gain access to or alter sensitive user data. In addition, users often lack full control over how their stored data is managed and protected.

To address these challenges, this project proposes a Decentralized Secure Cloud Storage System using Blockchain technology and IPFS (InterPlanetary File System). In the proposed system, user files are first encrypted using the AES encryption algorithm to ensure confidentiality before storage. The encrypted files are then divided into multiple blocks and uploaded to distributed IPFS nodes, where each block receives a unique content-based hash value. These hash values are securely stored on the blockchain using smart contracts, ensuring tamper-proof metadata management. Blockchain provides immutability, transparency, and secure tracking of file references, while IPFS ensures decentralized and highly available distributed storage.