Architecture Overview

Core Components

graph TB
    subgraph "Arch Network"
        VM[Arch VM<br/>eBPF-based]
        BTC[Bitcoin Integration]
        
        subgraph "Validator Network"
            L[Leader Node]
            V1[Validator Node 1]
            V2[Validator Node 2]
            V3[Validator Node ...]
            B[Bootnode]
        end
        
        VM --> BTC
        L --> V1
        L --> V2
        L --> V3
        B --> V1
        B --> V2
        B --> V3
    end

Arch VM

The Arch Virtual Machine (VM) is built on eBPF technology, providing a secure and efficient environment for executing programs.

Key features:

🔄 Manages program execution
⚡ Handles state transitions
🎯 Ensures deterministic computation
🔗 Provides syscalls for Bitcoin UTXO operations

Bitcoin Integration

Arch Network interacts directly with Bitcoin through:

💼 Native UTXO management
✅ Transaction validation
🔐 Multi-signature coordination
📝 State commitment to Bitcoin

Validator Network

The validator network consists of multiple node types that work together:

Node Types

Node Type	Primary Responsibilities
Leader Node	• Coordinates transaction signing • Submits signed transactions to Bitcoin • Manages validator communication
Validator Nodes	• Execute programs in the Arch VM • Validate transactions • Participate in multi-signature operations • Maintain network state
Bootnode	• Handles initial network discovery • Similar to Bitcoin DNS seeds • Helps new nodes join the network

Transaction Flow

sequenceDiagram
    participant C as Client
    participant L as Leader
    participant V as Validators
    participant B as Bitcoin Network
    
    C->>L: 1. Submit Transaction
    L->>V: 2. Distribute to Validators
    V->>V: 3. Execute in Arch VM
    V->>L: 4. Sign Results
    L->>B: 5. Submit to Bitcoin

Security Model

Arch Network implements a robust multi-layered security model that directly leverages Bitcoin's security guarantees:

1. UTXO Security

🔒 Ownership Verification
- Public key cryptography using secp256k1
- BIP322 message signing for secure ownership proofs
- Double-spend prevention through UTXO consumption tracking
🔗 State Management
- State anchoring to Bitcoin transactions
- Atomic state transitions with rollback capability
- Cross-validator state consistency checks

2. Transaction Security

pub struct SecurityParams {
    pub min_confirmations: u32,    // Required Bitcoin confirmations
    pub signature_threshold: u32,   // Multi-sig threshold
    pub timelock_blocks: u32,      // Timelock requirement
    pub max_witness_size: usize    // Maximum witness data size
}

📝 Multi-signature Validation
- ROAST protocol for distributed signing
- Threshold signature scheme (t-of-n)
- Malicious signer detection and removal
- Binding factor verification for signature shares

3. Network Security

🌐 Validator Selection
```
pub struct ValidatorSet {
    pub validators: Vec<ValidatorInfo>,
    pub threshold: u32
}
```
- Stake-weighted validator participation
- Dynamic threshold adjustment
- Automatic malicious node detection
🛡️ State Protection
- Multi-stage transaction verification
- Bitcoin-based finality guarantees
- State root commitment to Bitcoin
- Mandatory signature verification for all state changes

4. Best Practices

✅ UTXO Management
- Minimum 6 confirmations for finality
- Comprehensive UTXO validation
- Double-spend monitoring
- Reorg handling for UTXO invalidation
🔍 Transaction Processing
- Full signature verification
- Input/output validation
- Proper error handling
- Network partition handling

The Arch Book