Decentralized document verification system through Polygon blockchain

DocHash consists of three main components

Smart Contracts - Solidity contract for storing SHA-512 document hashes on Polygon blockchain
Backend API - Litestar server with PostgreSQL for file processing and blockchain synchronization
Frontend Web - Svelte application for user interface registration and verification

• Solidity smart contract for Polygon network
• Functions for storing and retrieving document hashes
• Support for localhost, Mumbai testnet, Polygon mainnet
• Unique verification_id for each document

• Litestar API server with asynchronous architecture
• PostgreSQL database for blockchain data caching
• Web3.py integration for contract interaction
• Blockchain worker for event monitoring
• SHA-512 hashing for contract compatibility

• Svelte web interface with modular architecture
• Drag-and-drop PDF document upload
• Registration and verification interfaces
• Docker containerization with Nginx

1. User uploads PDF file through web interface
2. System generates SHA-512 hash of document
3. Hash is recorded in blockchain contract with unique ID
4. User receives verification_id for future verification

Document authenticity check through three methods

• By verification_id received during registration
• By original PDF file through re-hashing
• By known SHA-512 hash of document

System returns authenticity status with metadata

• Verification status (found/not found in blockchain)
• Blockchain record timestamp
• Creator address
• Transaction details

Blockchain Networks

• Polygon Mainnet for production
• Mumbai Testnet for testing
• Localhost Hardhat for development

Performance

• Recording cost around 0.001-0.01 MATIC
• Data reading is free
• Asynchronous API request processing

Security

• Cryptographic SHA-512 hashing
• Immutable blockchain records
• Document integrity verification
• Forgery protection through decentralization

dochash/
├── contracts/          # Solidity contracts and deploy scripts
├── backend/           # API server and blockchain worker  
└── frontend/          # Svelte web application

cd contracts
npm install && npm run compile
npm run deploy-testnet

cd backend
docker-compose up --build

cd frontend
yarn && yarn build
docker run -p 80:80 dochash-frontend

DocHash solves document verification tasks in areas where authenticity is critical

• Legal documentation and contracts
• Academic diplomas and certificates
• Medical records and prescriptions
• Financial reporting
• Intellectual property
• Government documents

The system provides transparent and immutable recording of document existence at a specific point in time without revealing content