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System Architecture Diagram
This document presents the complete system architecture diagram for the Blockchain Voting System with ZK privacy and gasless transactions.
Architecture Overview
The Blockchain Voting System follows a layered architecture that separates concerns while maintaining seamless integration between components. The system combines traditional web application patterns with blockchain technology and zero-knowledge privacy.
┌─────────────────────────────────────────────────────────────────────────────┐
│ FRONTEND LAYER │
├─────────────────────────────────────────────────────────────────────────────┤
│ │
│ ┌─────────────────┐ │
│ │ Web Browser │ │
│ │ (React/Vite) │ │
│ └─────────────────┘ │
│ │ │
│ ▼ │
│ ┌─────────────────┐ │
│ │ Admin Portal │ │
│ │ (React/Admin) │ │
│ └─────────────────┘ │
│ │ │
│ ▼ │
│ ┌─────────▼─────────┐ │
│ │ API Gateway │ │
│ │ (REST/GraphQL) │ │
│ └─────────┬─────────┘ │
└───────────────────────────────────┼─────────────────────────────────────────┘
│
┌───────────────────────────────────┼─────────────────────────────────────────┐
│ BACKEND LAYER │
├───────────────────────────────────┼─────────────────────────────────────────┤
│ │ │
│ ┌─────────▼─────────┐ │
│ │ Web Application │ │
│ │ Server │ │
│ │ (Node.js/Hono) │ │
│ └─────────┬─────────┘ │
│ │ │
│ ┌──────────────┼──────────────┐ │
│ │ │ │ │
│ ┌─────────▼─────────┐ │ ┌─────────▼─────────┐ │
│ │ Authentication & │ │ │ Business Logic │ │
│ │ Session Mgmt │ │ │ │ │
│ └─────────────────┘ │ └─────────────────┘ │
│ │ │ │ │
│ ┌─────────▼─────────┐ │ ┌─────────▼─────────┐ │
│ │ ZK Proof Gen │ │ │ Election Mgmt │ │
│ │ & Validation │ │ │ │ │
│ └─────────────────┘ │ └─────────────────┘ │
│ │ │ │ │
│ ┌─────────▼─────────┐ │ ┌─────────▼─────────┐ │
│ │ Blockchain Relay │ │ │ Database Access │ │
│ │ Service │ │ │ │ │
│ └─────────────────┘ │ └─────────────────┘ │
│ │ │ │ │
│ └──────────────┼──────────────┘ │
│ │ │
│ ┌─────────▼─────────┐ │
│ │ Storage │ │
│ │ (PostgreSQL) │ │
│ └─────────┬─────────┘ │
└───────────────────────────────────┼─────────────────────────────────────────┘
│
┌───────────────────────────────────┼─────────────────────────────────────────┐
│ BLOCKCHAIN LAYER │
├───────────────────────────────────┼─────────────────────────────────────────┤
│ │ │
│ ┌─────────▼─────────┐ │
│ │ Smart Contracts │ │
│ │ │ │
│ │ ┌─────────────┐ │ │
│ │ │ VotingSystem│ │ │
│ │ ├─────────────┤ │ │
│ │ │ Election │ │ │
│ │ ├─────────────┤ │ │
│ │ │ Party │ │ │
│ │ ├─────────────┤ │ │
│ │ │ Candidate │ │ │
│ │ ├─────────────┤ │ │
│ │ │ Voter │ │ │
│ │ └─────────────┘ │ │
│ └─────────┬─────────┘ │
│ │ │
│ ┌─────────▼─────────┐ │
│ │ ZK Circuits │ │
│ │ (Semaphore) │ │
│ └─────────┬─────────┘ │
│ │ │
│ ┌─────────▼─────────┐ │
│ │ Blockchain │ │
│ │ (Polygon/Mumbai) │ │
│ └───────────────────┘ │
└─────────────────────────────────────────────────────────────────────────────┘Layer-by-Layer Explanation
1. Frontend Layer
Web Browser
- Technology: React with Vite
- Purpose: Primary voting interface for voters
- Features:
- Voter registration and authentication
- Election browsing and information display
- Voting interface with candidate selection
- Real-time election results display
- Responsive design for various devices
Admin Portal
- Technology: React with Admin Dashboard components
- Purpose: Election administration interface
- Features:
- Election creation and management
- Voter registration and verification
- Candidate and party management
- Real-time monitoring and analytics
- Results visualization and reporting
2. Backend Layer
API Gateway
- Technology: REST/GraphQL API
- Purpose: Entry point for all client requests
- Features:
- Request routing and load balancing
- Authentication and authorization
- Rate limiting and security
- API documentation (Swagger/OpenAPI)
Web Application Server
- Technology: Node.js with Hono framework
- Purpose: Core business logic execution
- Features:
- Request processing and response generation
- Session and user management
- Business rule enforcement
- Error handling and logging
Authentication & Session Management
- Purpose: User authentication and session handling
- Features:
- Voter and admin authentication
- Session token generation and validation
- Password hashing and security
- JWT token management
ZK Proof Generation & Validation
- Purpose: Zero-knowledge proof handling
- Features:
- Semaphore identity generation
- ZK proof generation for voter eligibility
- Proof validation before blockchain submission
- Integration with Semaphore circuits
Blockchain Relay Service
- Purpose: Bridge between traditional web and blockchain
- Features:
- Gasless transaction handling
- Wallet management for transaction signing
- Transaction monitoring and confirmation
- Error handling and retry mechanisms
Business Logic
- Purpose: Core voting system functionality
- Features:
- Election lifecycle management
- Voting process orchestration
- Results calculation and aggregation
- Validation and verification workflows
Database Access
- Purpose: Data persistence and retrieval
- Features:
- Voter information storage
- Election and candidate data management
- Vote records and audit trails
- Performance optimization and caching
Storage
- Technology: PostgreSQL database
- Purpose: Persistent data storage
- Features:
- ACID compliance for data integrity
- Scalable storage for voter records
- Election and candidate information
- Audit logs and historical data
3. Blockchain Layer
Smart Contracts
- Technology: Solidity on Ethereum-compatible chains
- Purpose: Immutable voting record storage
- Components:
- VotingSystem: Central coordinator for elections
- Election: Individual election management
- Party: Political party representation
- Candidate: Candidate information storage
- Voter: Voter registration and verification
ZK Circuits
- Technology: Semaphore protocol
- Purpose: Zero-knowledge privacy implementation
- Features:
- Anonymous signaling for voter eligibility
- Group membership verification
- Double voting prevention
- Identity privacy preservation
Blockchain
- Technology: Polygon/Mumbai testnet
- Purpose: Decentralized and immutable record storage
- Features:
- Transaction finality and immutability
- Public verification of results
- Decentralized consensus
- Low-cost transactions
Data Flow Explanation
Voter Registration Flow
- User registers through frontend
- Backend generates Semaphore identity
- Identity commitment stored in database
- Identity commitment added to blockchain group
- User receives encrypted secret for future voting
Voting Flow
- User authenticates through frontend
- Backend retrieves user's identity secret
- Backend generates ZK proof of group membership
- Backend submits vote transaction (pays gas)
- Blockchain validates ZK proof
- Vote recorded with privacy guarantees
- Results available for public verification
Results Flow
- Anyone can query election results
- Frontend requests results from backend
- Backend fetches from blockchain
- Results displayed with transparency
- ZK proofs ensure vote integrity
Security Architecture
Privacy Protection
- ZK Proofs: Voter anonymity through Semaphore
- Encrypted Storage: Identity secrets in database
- Gas Abstraction: Hide blockchain complexity
- Access Controls: Role-based permissions
Integrity Assurance
- Immutable Records: Blockchain storage
- Proof Verification: Mathematical verification
- Audit Trails: Complete transaction history
- Consensus Mechanisms: Decentralized validation
Availability
- Redundancy: Multiple backend instances
- Caching: Performance optimization
- Load Balancing: Scalable architecture
- Failover: High availability design
Scalability Considerations
Horizontal Scaling
- Microservices: Independent component scaling
- Load Balancing: Distribute frontend requests
- Database Sharding: Partition data for performance
- Caching Layers: Reduce database load
Blockchain Optimization
- Batch Operations: Reduce transaction count
- Light Clients: Minimize blockchain queries
- Event Indexing: Efficient data retrieval
- Off-chain Computation: Reduce on-chain operations
This architecture provides a balance between usability, privacy, and blockchain benefits while maintaining the scalability needed for real-world voting systems.