Secure File Sharing System With Blockchain-based Time-Locked Access Control Encrypted With Symmetric Algorithms

Abstract

Blockchain mechanism, having its distributed and immutable nature, has become a revolutionary method of secure and transparent data exchange. With this potential in mind, our proposal is for Secure File Sharing System that combines AES-256&DES encryption with Ethereum smart contracts to provide a privacy-oriented and audit-ready file sharing system. The conventional centralized approach is prone to data leakages and unauthenticated access, but with the use of blockchain and encryption, this approach provides confidentiality along with trustless verification. Files are first encrypted at the server level using AES, DES symmetric encryption, thus avoiding any plaintext exposure at the server level. The file is stored encrypted within a cloud storage service called cloudinary, with sensitive metadata such as hashed file ID, destination wallet address, and unlock timestamp stored on the Ethereum blockchain through smart contracts. The blockchain layer delivers traceability and immutability with accessed file records being tamperproof. In addition, there is a time-lock mechanism in the smart contract that doesn't allow recipients to access files before the unlock time, thereby improving security and governance. The React.js frontend communicates with blockchain networks using MetaMask and ethers.js, while the Node.js and Express backend encrypts and decrypts the files, and stores metadata in MongoDB. This two-way hybrid approach effectively addresses attacks such as unauthorized access, man-in-the-middle, and data tampering. With this blend of blockchain's decentralized trust and AES's and DES's secrecy, this project lays out an innovative and viable model for secure file sharing digitally. It is robust in possible application to actual applications like enterprise document management, transfer of legal documents, and confidential communication, and provides a secure, transparent, and scalable solution.