Build a Blockchain-Based Document Storage App

Centralized file systems are vulnerable to tampering, data loss, and access issues. This app development project enables users to upload and verify documents using IPFS and record hashes on a blockchain for authenticity, traceability, and security.

Users upload documents which are stored on IPFS. A hash of the file is saved on a blockchain (Ethereum or Polygon) for verification. Later, users can retrieve and verify any file’s authenticity by matching hashes and timestamps.

A user uploads a document. The app stores it on IPFS and computes its hash. A smart contract records the hash, timestamp, and optional metadata. When another user accesses the document, they retrieve it from IPFS and verify integrity by comparing the stored blockchain hash.

• User selects a file and uploads it via the app.
• The file is uploaded to IPFS, and a CID is generated.
• The CID and file hash are sent to a blockchain smart contract and recorded with a timestamp.
• Anyone can later retrieve the file from IPFS and verify its hash against the on-chain record.
• Optional: Add role-based access, encrypted files, or expiry control via smart contract logic.

• IPFS Documentation
• Pinata IPFS Upload API
• Solidity Smart Contract Basics
• Web3.js File Upload Tutorial
• Ethers.js Documentation