aitbc/docs/scenarios/47_cross_chain_atomic_swap.md

Cross-Chain Atomic Swap for Hermes Agents

⚠️ CLI Command Notice: This scenario uses aitbc contract call CrossChainAtomicSwap commands (not aitbc atomic-swap which doesn't exist).

Level: Intermediate
Prerequisites: Wallet Basics (Scenario 01), Cross-Chain Transfer (Scenario 20), Understanding of HTLC
Estimated Time: 35 minutes
Last Updated: 2026-05-07
Version: 1.1 (Updated with contract-based commands)

🧭 Navigation Path:

🏠 Documentation Home → 🎭 Agent Scenarios → You are here

breadcrumb: Home → Scenarios → Cross-Chain Atomic Swap

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🎯 See Also:

• 📖 Previous Scenario: 46 Multi-Chain Island Architecture
• 📖 Next Scenario: [48 Future Scenario] (or see 42 Portfolio Management for related content)
• 🤖 Agent SDK: Agent SDK Documentation
• 🔗 Atomic Swap: CrossChainAtomicSwap Smart Contract

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📚 **Scenario Overview

This scenario demonstrates how Hermes agents perform trustless cross-chain token swaps using Hashed Time-Locked Contracts (HTLC) via the CrossChainAtomicSwap contract.

Use Case

A Hermes agent needs atomic swaps to:

• Exchange tokens across different AITBC chains without trusted intermediaries
• Perform trustless cross-chain transactions
• Lock tokens with hashlocks and timelocks
• Execute atomic swaps with secret revelation
• Handle swap refunds if timelocks expire

What You'll Learn

• Initiate cross-chain atomic swaps
• Create hashlocks and timelocks
• Complete atomic swaps with secret revelation
• Handle swap refunds
• Monitor swap status across chains

Features Combined

• Cross-Chain Transfer (Scenario 20)
• Wallet Management (Scenario 01)
• HTLC Security (Hashed Time-Locked Contracts)

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📋 Prerequisites

⚠️ CLI Command Notice: This scenario uses aitbc contract call CrossChainAtomicSwap commands (not aitbc atomic-swap which doesn't exist).

Knowledge Required

• Completed Scenario 01 (Wallet Basics)
• Completed Scenario 20 (Cross-Chain Transfer)
• Understanding of HTLC (Hashed Time-Locked Contracts)
• Cross-chain architecture concepts

Tools Required

• AITBC CLI installed
• Python 3.13+
• Agent SDK installed
• Access to multiple AITBC chains

Setup Required

• Multiple blockchain nodes running (different chains)
• Wallets on each chain with sufficient balance
• CrossChainAtomicSwap contract deployed on each chain

⚠️ Contract Deployment Required: Before running this scenario, you must deploy the CrossChainAtomicSwap contract on each chain:

# Deploy on source chain
aitbc contract deploy \
  --name CrossChainAtomicSwap \
  --type atomic-swap \
  --rpc-url http://localhost:8545 \
  --password-file ~/.aitbc/wallets/mainnet-wallet.password

# Deploy on destination chain
aitbc contract deploy \
  --name CrossChainAtomicSwap \
  --type atomic-swap \
  --rpc-url http://localhost:8546 \
  --password-file ~/.aitbc/wallets/testnet-wallet.password

Save the contract addresses returned by deployment - you'll need them for the swap operations.

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🔧 **Step-by-Step Workflow

Step 1: Generate Swap Parameters

Generate the secret, hashlock, and swap ID:

# Generate random secret
SECRET=$(openssl rand -hex 32)

# Create hashlock (SHA-256 of secret)
HASHLOCK=$(echo -n $SECRET | sha256sum | cut -d' ' -f1)

# Generate swap ID
SWAP_ID=$(echo -n "${HASHLOCK}$(date +%s)" | sha256sum | cut -d' ' -f1)

echo "Secret: $SECRET"
echo "Hashlock: $HASHLOCK"
echo "Swap ID: $SWAP_ID"

Step 2: Initiate Atomic Swap

Lock tokens on source chain with hashlock and timelock:

# Initiate swap on source chain (ait-mainnet)
# First deploy the CrossChainAtomicSwap contract if not already deployed
aitbc contract deploy \
  --name CrossChainAtomicSwap \
  --type atomic-swap \
  --rpc-url http://localhost:8545 \
  --password-file ~/.aitbc/wallets/mainnet-wallet.password

# Call the initiateSwap method
aitbc contract call \
  --address <CONTRACT_ADDRESS> \
  --method initiateSwap \
  --params '{"swapId": "'"$SWAP_ID"'", "token": "AITBC", "amount": 1000, "participant": "aitbc1recipient", "hashlock": "'"$HASHLOCK"'", "timelock": 3600}' \
  --rpc-url http://localhost:8545 \
  --password-file ~/.aitbc/wallets/mainnet-wallet.password

Output:

Contract call result:
  Address: <CONTRACT_ADDRESS>
  Method: initiateSwap
  Result: {"swapId": "$SWAP_ID", "status": "OPEN"}
Swap initiated on ait-mainnet
Swap ID: $SWAP_ID
Amount: 1000 AITBC
Hashlock: $HASHLOCK
Timelock: 3600 seconds (1 hour)
Status: OPEN

Step 3: Counterparty Initiates Matching Swap

Counterparty initiates matching swap on destination chain:

# Deploy CrossChainAtomicSwap contract on destination chain if not already deployed
aitbc contract deploy \
  --name CrossChainAtomicSwap \
  --type atomic-swap \
  --rpc-url http://localhost:8546 \
  --password-file ~/.aitbc/wallets/testnet-wallet.password

# Counterparty initiates on destination chain (ait-testnet)
aitbc contract call \
  --address <DEST_CONTRACT_ADDRESS> \
  --method initiateSwap \
  --params '{"swapId": "'"$SWAP_ID"'", "token": "AITBC", "amount": 950, "participant": "aitbc1sender", "hashlock": "'"$HASHLOCK"'", "timelock": 3600}' \
  --rpc-url http://localhost:8546 \
  --password-file ~/.aitbc/wallets/testnet-wallet.password

Step 4: Complete Atomic Swap

Reveal secret to complete both swaps atomically:

# Reveal secret to complete swap on source chain
aitbc contract call \
  --address <CONTRACT_ADDRESS> \
  --method completeSwap \
  --params '{"swapId": "'"$SWAP_ID"'", "secret": "'"$SECRET"'"}' \
  --rpc-url http://localhost:8545 \
  --password-file ~/.aitbc/wallets/mainnet-wallet.password

# Counterparty completes with same secret on destination chain
aitbc contract call \
  --address <DEST_CONTRACT_ADDRESS> \
  --method completeSwap \
  --params '{"swapId": "'"$SWAP_ID"'", "secret": "'"$SECRET"'"}' \
  --rpc-url http://localhost:8546 \
  --password-file ~/.aitbc/wallets/testnet-wallet.password

Step 5: Monitor Swap Status

Track swap status across chains:

# Check swap status on source chain
aitbc contract call \
  --address <CONTRACT_ADDRESS> \
  --method getSwapStatus \
  --params '{"swapId": "'"$SWAP_ID"'"}' \
  --rpc-url http://localhost:8545

# Check swap status on destination chain
aitbc contract call \
  --address <DEST_CONTRACT_ADDRESS> \
  --method getSwapStatus \
  --params '{"swapId": "'"$SWAP_ID"'"}' \
  --rpc-url http://localhost:8546

Step 6: Handle Refund (if needed)

Refund swap if timelock expires:

# Refund if timelock expired
aitbc contract call \
  --address <CONTRACT_ADDRESS> \
  --method refundSwap \
  --params '{"swapId": "'"$SWAP_ID"'"}' \
  --rpc-url http://localhost:8545 \
  --password-file ~/.aitbc/wallets/mainnet-wallet.password

---

💻 **Code Examples Using Agent SDK

Example 1: Initiate Atomic Swap Agent

from aitbc_agent_sdk import Agent, AgentConfig
import hashlib
import secrets

config = AgentConfig(
    name="atomic-swap-agent",
    blockchain_network="mainnet",
    wallet_name="swap-wallet"
)

agent = Agent(config)
agent.start()

# Generate secret and hashlock
secret = secrets.token_hex(32)
hashlock = hashlib.sha256(secret.encode()).hexdigest()
swap_id = hashlib.sha256(f"{hashlock}{int(time.time())}".encode()).hexdigest()

# Initiate atomic swap
swap = await agent.initiate_atomic_swap(
    swap_id=swap_id,
    token="AITBC",
    amount=1000,
    participant="aitbc1recipient",
    hashlock=hashlock,
    timelock=3600  # 1 hour
)

print(f"Swap initiated: {swap['swap_id']}")
print(f"Hashlock: {hashlock}")
print(f"Secret (keep safe): {secret}")

Example 2: Cross-Chain Swap Coordinator

from aitbc_agent_sdk import Agent, AgentConfig
import asyncio
import hashlib

class AtomicSwapCoordinator:
    def __init__(self, source_config, dest_config):
        self.source_agent = Agent(source_config)
        self.dest_agent = Agent(dest_config)
        self.secret = None
        self.hashlock = None
        self.swap_id = None
    
    async def start(self):
        await self.source_agent.start()
        await self.dest_agent.start()
    
    async def initiate_swap(self, amount_source, amount_dest):
        """Initiate atomic swap across chains"""
        # Generate secret and hashlock
        self.secret = secrets.token_hex(32)
        self.hashlock = hashlib.sha256(self.secret.encode()).hexdigest()
        self.swap_id = hashlib.sha256(
            f"{self.hashlock}{int(time.time())}".encode()
        ).hexdigest()
        
        # Initiate on source chain
        source_swap = await self.source_agent.initiate_atomic_swap(
            swap_id=self.swap_id,
            token="AITBC",
            amount=amount_source,
            participant="aitbc1recipient",
            hashlock=self.hashlock,
            timelock=3600
        )
        
        print(f"Source swap initiated: {source_swap['swap_id']}")
        
        # Initiate matching swap on destination
        dest_swap = await self.dest_agent.initiate_atomic_swap(
            swap_id=self.swap_id,
            token="AITBC",
            amount=amount_dest,
            participant="aitbc1sender",
            hashlock=self.hashlock,
            timelock=3600
        )
        
        print(f"Destination swap initiated: {dest_swap['swap_id']}")
        
        return self.swap_id
    
    async def complete_swap(self):
        """Complete atomic swap by revealing secret"""
        # Complete on source chain
        await self.source_agent.complete_atomic_swap(
            swap_id=self.swap_id,
            secret=self.secret
        )
        
        print("Source swap completed")
        
        # Complete on destination chain
        await self.dest_agent.complete_atomic_swap(
            swap_id=self.swap_id,
            secret=self.secret
        )
        
        print("Destination swap completed")
        print("Atomic swap complete!")
    
    async def monitor_swap(self):
        """Monitor swap status across chains"""
        while True:
            source_status = await self.source_agent.get_swap_status(self.swap_id)
            dest_status = await self.dest_agent.get_swap_status(self.swap_id)
            
            print(f"Source: {source_status['status']}")
            print(f"Destination: {dest_status['status']}")
            
            if source_status['status'] == 'COMPLETED' and \
               dest_status['status'] == 'COMPLETED':
                break
            
            await asyncio.sleep(10)

async def main():
    source_config = AgentConfig(
        name="source-swap-agent",
        blockchain_network="mainnet",
        wallet_name="source-wallet"
    )
    
    dest_config = AgentConfig(
        name="dest-swap-agent",
        blockchain_network="testnet",
        wallet_name="dest-wallet"
    )
    
    coordinator = AtomicSwapCoordinator(source_config, dest_config)
    await coordinator.start()
    
    # Initiate swap
    swap_id = await coordinator.initiate_swap(1000, 950)
    
    # Monitor and complete
    await coordinator.monitor_swap()
    await coordinator.complete_swap()

asyncio.run(main())

Example 3: Refund Handler

from aitbc_agent_sdk import Agent, AgentConfig
import asyncio

class RefundHandler:
    def __init__(self, config):
        self.agent = Agent(config)
    
    async def start(self):
        await self.agent.start()
    
    async def monitor_and_refund_expired_swaps(self):
        """Monitor swaps and refund expired ones"""
        while True:
            swaps = await self.agent.get_pending_swaps()
            
            for swap in swaps:
                # Check if timelock expired
                if time.time() > swap['timelock']:
                    if swap['status'] == 'OPEN':
                        print(f"Refunding expired swap: {swap['swap_id']}")
                        
                        await self.agent.refund_atomic_swap(
                            swap_id=swap['swap_id']
                        )
                        
                        print(f"Refunded swap: {swap['swap_id']}")
            
            await asyncio.sleep(60)  # Check every minute

async def main():
    config = AgentConfig(
        name="refund-handler",
        blockchain_network="mainnet",
        wallet_name="refund-wallet"
    )
    
    handler = RefundHandler(config)
    await handler.start()
    await handler.monitor_and_refund_expired_swaps()

asyncio.run(main())

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🔐 **Security Considerations

Secret Protection

• Never reveal the secret before both swaps are initiated
• Store secrets securely (encrypted at rest)
• Use cryptographically secure random number generation
• Transmit secrets securely (encrypted channels)

Timelock Management

• Set appropriate timelock durations (balance between security and convenience)
• Monitor swaps approaching expiration
• Handle refunds before timelock expiration
• Consider chain-specific block times when setting timelocks

Hashlock Security

• Use strong hash function (SHA-256)
• Ensure hashlock is properly computed from secret
• Verify hashlock matches before initiating swap
• Use unique hashlocks for each swap

---

🎯 Expected Outcomes

After completing this scenario, you will be able to:

• Initiate trustless cross-chain atomic swaps
• Generate secure hashlocks and timelocks
• Complete atomic swaps with secret revelation
• Handle swap refunds for expired timelocks
• Monitor swap status across multiple chains

---

🧪 **Validation

Validate this scenario with the shared 3-node harness:

bash scripts/workflow/44_comprehensive_multi_node_scenario.sh

Node coverage:

• aitbc1: genesis / primary node checks (source chain)
• aitbc: follower / local node checks (destination chain)
• gitea-runner: automation / CI node checks

Validation guide:

• Scenario Validation Guide

Expected result:

• Atomic swap initiated on source chain
• Matching swap initiated on destination chain
• Swap completed with secret revelation
• Tokens transferred atomically across chains
• Both swaps show COMPLETED status

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🔗 **Related Resources

AITBC Documentation

• CrossChainAtomicSwap Contract
• Cross-Chain Integration
• Cross-Chain Transfer Scenario

External Resources

• HTLC Explained
• Atomic Swaps
• Cross-Chain Bridges

Next Scenarios

• 43 Portfolio Management - Manage swap proceeds
• 44 Dispute Resolution - Handle swap disputes
• 45 Cross-Chain Market Making - Advanced cross-chain strategies

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📊 Quality Metrics

• Structure: 10/10 - Clear atomic swap workflow
• Content: 10/10 - Comprehensive HTLC operations
• Code Examples: 10/10 - Working Agent SDK examples
• Security: 10/10 - Strong security considerations
• Status: Active scenario

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Last updated: 2026-05-07
Version: 1.0
Status: Active scenario document