Build a Blockchain-Based Document Timestamping System

In legal, academic, and business contexts, proving that a document existed at a specific time is critical. Blockchain enables tamper-proof, decentralized timestamping by storing cryptographic hashes rather than full documents.

Develop a platform that allows users to upload a document, hash it locally, and store the hash and timestamp on the blockchain. Later, users or third parties can verify document integrity by comparing hashes.

Users upload files through the frontend, where a hash (SHA-256 or Keccak256) is generated locally. The hash and timestamp are submitted to a smart contract. Later, the same hash can be used to verify that the document existed unchanged.

• React.js frontend with file upload and hash generation
• Smart contract for storing hashes and block timestamps
• IPFS optional for storing original files (if public)
• MetaMask or WalletConnect for blockchain interaction
• Keccak256/SHA256 for local hashing

• Solidity Hash Storage Example
• crypto-js for SHA256 in React
• File Upload to IPFS Guide
• Ethers.js Integration Guide