# Qbitcoin Technical Architecture

## System Architecture Overview

```mermaid
graph TB
    subgraph "Application Layer"
        A1[Web GUI]
        A2[Desktop Wallet]
        A3[Mobile Apps]
        A4[CLI Tools]
        A5[Third-party Apps]
    end
    
    subgraph "API Gateway Layer"
        B1[REST API Server]
        B2[gRPC Server]
        B3[WebSocket Server]
        B4[Mining API]
        B5[Admin API]
    end
    
    subgraph "Service Layer"
        C1[Transaction Service]
        C2[Block Service]
        C3[Wallet Service]
        C4[Mining Service]
        C5[Network Service]
    end
    
    subgraph "Core Business Logic"
        D1[Chain Manager]
        D2[Transaction Pool]
        D3[State Manager]
        D4[Multi-Sig Manager]
        D5[Token Manager]
        D6[Consensus Engine]
    end
    
    subgraph "Cryptography Layer"
        E1[FALCON-512 Engine]
        E2[Hash Functions]
        E3[Address Generator]
        E4[Key Manager]
        E5[Signature Validator]
    end
    
    subgraph "Network Layer"
        F1[P2P Protocol]
        F2[Peer Discovery]
        F3[Message Router]
        F4[Connection Manager]
        F5[Rate Limiter]
    end
    
    subgraph "Storage Layer"
        G1[Block Database]
        G2[State Database]
        G3[Transaction Index]
        G4[Peer Database]
        G5[Configuration]
    end
    
    subgraph "Mining Layer"
        H1[QryptoNight Miner]
        H2[QRandomX Miner]
        H3[Difficulty Tracker]
        H4[Block Template]
        H5[Proof Validator]
    end
    
    %% Connections
    A1 --> B1
    A2 --> B2
    A3 --> B3
    A4 --> B1
    A5 --> B1
    
    B1 --> C1
    B2 --> C2
    B3 --> C3
    B4 --> C4
    B5 --> C5
    
    C1 --> D1
    C2 --> D2
    C3 --> D3
    C4 --> D4
    C5 --> D5
    
    D1 --> E1
    D2 --> E2
    D3 --> E3
    D4 --> E4
    D5 --> E5
    D6 --> E1
    
    D1 --> F1
    D2 --> F2
    D6 --> F3
    
    F1 --> G1
    F2 --> G2
    F3 --> G3
    
    D6 --> H1
    D6 --> H2
    H1 --> H3
    H2 --> H4
    
    %% Storage connections
    D1 --> G1
    D2 --> G2
    D3 --> G3
    F2 --> G4
    C5 --> G5
```

## Component Descriptions

### Application Layer
- **Web GUI**: Browser-based interface for blockchain interaction
- **Desktop Wallet**: Native desktop application with full features
- **Mobile Apps**: iOS and Android applications for basic operations
- **CLI Tools**: Command-line utilities for advanced users
- **Third-party Apps**: External applications using Qbitcoin APIs

### API Gateway Layer
- **REST API Server**: HTTP-based API for web integration
- **gRPC Server**: High-performance RPC for backend services
- **WebSocket Server**: Real-time updates and notifications
- **Mining API**: Specialized API for mining pool integration
- **Admin API**: Administrative functions for node operators

### Service Layer
- **Transaction Service**: Transaction creation, validation, and broadcasting
- **Block Service**: Block retrieval, validation, and chain operations
- **Wallet Service**: Wallet management and key operations
- **Mining Service**: Mining coordination and block template generation
- **Network Service**: P2P network management and peer coordination

### Core Business Logic
- **Chain Manager**: Blockchain state management and fork resolution
- **Transaction Pool**: Pending transaction management and ordering
- **State Manager**: Account balances and state transitions
- **Multi-Sig Manager**: Multi-signature wallet operations
- **Token Manager**: Custom token creation and transfers
- **Consensus Engine**: Proof-of-work consensus implementation

### Cryptography Layer
- **FALCON-512 Engine**: Post-quantum signature implementation
- **Hash Functions**: SHA-256 and other cryptographic hashing
- **Address Generator**: Quantum-safe address derivation
- **Key Manager**: Private key storage and management
- **Signature Validator**: Batch signature verification

### Network Layer
- **P2P Protocol**: Peer-to-peer communication protocol
- **Peer Discovery**: Network topology management
- **Message Router**: Message routing and propagation
- **Connection Manager**: Connection lifecycle management
- **Rate Limiter**: Anti-spam and DoS protection

### Storage Layer
- **Block Database**: Persistent block storage using LevelDB
- **State Database**: Account states and balances
- **Transaction Index**: Fast transaction lookup
- **Peer Database**: Known peer information
- **Configuration**: Node configuration and settings

### Mining Layer
- **QryptoNight Miner**: Legacy mining algorithm implementation
- **QRandomX Miner**: Modern mining algorithm for CPU/GPU
- **Difficulty Tracker**: Dynamic difficulty adjustment
- **Block Template**: Mining template generation
- **Proof Validator**: Proof-of-work validation

## Data Flow Architecture

```mermaid
sequenceDiagram
    participant User
    participant API
    participant Service
    participant Core
    participant Crypto
    participant Network
    participant Storage
    
    User->>API: Submit Transaction
    API->>Service: Validate Request
    Service->>Core: Process Transaction
    Core->>Crypto: Verify Signature
    Crypto-->>Core: Signature Valid
    Core->>Storage: Check Balance
    Storage-->>Core: Balance Sufficient
    Core->>Network: Broadcast Transaction
    Network->>Storage: Store in Pool
    Storage-->>API: Transaction Accepted
    API-->>User: Confirmation Response
```

## Security Architecture

```mermaid
graph TD
    subgraph "Security Perimeter"
        A[Input Validation]
        B[Authentication]
        C[Authorization]
        D[Rate Limiting]
    end
    
    subgraph "Cryptographic Security"
        E[FALCON-512 Signatures]
        F[Hash Verification]
        G[Key Management]
        H[Secure Random Generation]
    end
    
    subgraph "Network Security"
        I[Peer Verification]
        J[Message Authentication]
        K[Connection Encryption]
        L[DoS Protection]
    end
    
    subgraph "Data Security"
        M[Database Encryption]
        N[Backup Security]
        O[Access Control]
        P[Audit Logging]
    end
    
    A --> E
    B --> F
    C --> G
    D --> H
    
    E --> I
    F --> J
    G --> K
    H --> L
    
    I --> M
    J --> N
    K --> O
    L --> P
```

## Performance Considerations

### Throughput Optimization
- **Parallel Validation**: Multi-threaded transaction processing
- **Signature Batching**: Batch verification of FALCON signatures
- **Database Optimization**: Efficient storage and retrieval
- **Network Optimization**: Message compression and batching

### Scalability Measures
- **Dynamic Block Size**: Adaptive block size based on network demand
- **State Pruning**: Remove old state data to reduce storage
- **Light Clients**: SPV support for mobile and web clients
- **Layer 2 Integration**: Payment channels and sidechains

### Memory Management
- **Transaction Pool**: Limited size with priority-based eviction
- **Block Cache**: LRU cache for frequently accessed blocks
- **State Cache**: In-memory cache for active account states
- **Peer Management**: Connection limits and cleanup

## Configuration Management

### Node Configuration
```yaml
# Qbitcoin Node Configuration
node:
  data_directory: "/home/user/.qbitcoin"
  log_level: "INFO"
  max_connections: 100
  
network:
  listen_port: 19000
  public_port: 19000
  bootstrap_peers:
    - "134.122.79.166:19000"
    - "220.158.73.254:19000"
    
mining:
  enabled: false
  mining_address: ""
  thread_count: 0  # Auto-detect
  
api:
  public_api:
    enabled: true
    host: "0.0.0.0"
    port: 19009
  admin_api:
    enabled: false
    host: "127.0.0.1"
    port: 19008
```

### Database Configuration
```yaml
# Database Settings
database:
  type: "leveldb"
  path: "blockchain_db"
  cache_size: "100MB"
  write_buffer_size: "4MB"
  compression: "snappy"
  
state_db:
  type: "leveldb"
  path: "state_db"
  cache_size: "200MB"
  bloom_filter_bits: 10
```
