Build a Blockchain-Based Document Timestamping System
Use blockchain to verify the existence and integrity of digital documents by storing their hashes and timestamps in a tamper-proof ledger.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.
Hash-Based Document Verification
Only the cryptographic hash of the file is stored, ensuring privacy and integrity.
Immutable Timestamps
Blockchain records the exact block time and hash entry, preventing forgery.
Proof of Existence
Anyone can independently verify that a document existed at a particular time.
File Integrity Checker
Re-upload a document to check if it matches a previously stored hash.
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
Blockchain
Ethereum or Polygon for transaction ledger
Smart Contracts
Solidity contract for hash registration and verification
Frontend
React.js with crypto-js or ethers.js for local hashing
Optional Storage
IPFS or Web3.Storage (if you want to store actual documents)
1. Build Smart Contract
Create a smart contract that stores a file hash and automatically records the block timestamp.
2. Set Up File Upload and Hashing
Use JavaScript libraries to hash files client-side and send the hash to the smart contract.
3. Integrate MetaMask
Allow users to connect their wallet and pay gas to store a timestamped hash.
4. Create Verification Interface
Allow re-uploading a document to hash and check against stored hashes for validation.
5. Optional: Add File Hosting via IPFS
Allow users to optionally upload the file to IPFS if public storage is acceptable.
Verify Documents Without Trust — Just Blockchain
Build a proof-of-existence platform that uses cryptographic hashes and blockchain to protect digital integrity.
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