Bitcoin-Stacks Bridge Contract

A secure cross-chain bridge enabling trustless transfers between Bitcoin and Stacks networks. This smart contract implements a robust validation system with multi-signature support for secure cross-chain transactions.

Features

• Secure Cross-Chain Transfers: Enable trustless transfers between Bitcoin and Stacks networks
• Multi-Validator Architecture: Distributed trust model with multiple validators
• Comprehensive Security Controls:
  • Input validation for all critical parameters
  • Safe arithmetic operations
  • Multiple security checks for transactions
  • Audit trail for validator operations
• Emergency Controls: Includes pause mechanism and emergency withdrawal functions
• Configurable Parameters: Adjustable minimum/maximum deposit amounts and confirmation requirements

Technical Specifications

Constants

• Minimum Deposit: 0.001 BTC (100,000 sats)
• Maximum Deposit: 10 BTC (1,000,000,000 sats)
• Required Confirmations: 6 blocks

Error Codes

ERR-NOT-AUTHORIZED (1000)           - Unauthorized access attempt
ERR-INVALID-AMOUNT (1001)           - Amount outside allowed range
ERR-INSUFFICIENT-BALANCE (1002)     - Insufficient funds for operation
ERR-INVALID-BRIDGE-STATUS (1003)    - Invalid bridge state
ERR-INVALID-SIGNATURE (1004)        - Invalid signature provided
ERR-ALREADY-PROCESSED (1005)        - Transaction already processed
ERR-BRIDGE-PAUSED (1006)           - Bridge is currently paused
ERR-INVALID-VALIDATOR-ADDRESS (1007) - Invalid validator address
ERR-INVALID-RECIPIENT-ADDRESS (1008) - Invalid recipient address
ERR-INVALID-BTC-ADDRESS (1009)      - Invalid Bitcoin address
ERR-INVALID-TX-HASH (1010)          - Invalid transaction hash
ERR-INVALID-SIGNATURE-FORMAT (1011)  - Invalid signature format

Core Functions

Administrative Functions

(initialize-bridge)     - Initialize the bridge contract
(pause-bridge)         - Pause bridge operations
(resume-bridge)        - Resume bridge operations
(add-validator)        - Add a new validator
(remove-validator)     - Remove an existing validator

User Functions

(initiate-deposit)     - Initiate a deposit from Bitcoin
(confirm-deposit)      - Confirm a deposit with validator signature
(withdraw)            - Withdraw funds to Bitcoin

Query Functions

(get-deposit)          - Get deposit details
(get-bridge-status)    - Get bridge operational status
(get-validator-status) - Check validator status
(get-balance)         - Get user balance
(verify-signature)     - Verify validator signature

Security Features

1. Input Validation

   • Principal address validation
   • Bitcoin address format checking
   • Transaction hash verification
   • Signature format validation

2. Safe Operations

   • Overflow protection in arithmetic operations
   • Balance checks before transfers
   • Duplicate transaction prevention

3. Access Control

   • Owner-only administrative functions
   • Validator-only confirmation functions
   • Protection against contract targeting

4. Audit Trail

   • Validator operations logging
   • Transaction history tracking
   • Timestamp recording for operations

Usage Flow

1. Deposit Process:

   Bitcoin Transaction → Initiate Deposit → Validator Confirmation → Funds Available
   

2. Withdrawal Process:

   Withdrawal Request → Balance Check → Event Emission → Off-chain Processing
   

Emergency Procedures

1. Bridge Pause

   • Owner can pause all operations in case of emergency
   • Existing balances remain secure
   • Only owner can resume operations

2. Emergency Withdrawal

   • Owner can process emergency withdrawals
   • Includes balance and recipient validation
   • Protected against overflow attacks

Development and Testing

Prerequisites

• Clarity CLI
• Bitcoin node (for testing)
• Stacks node (for deployment)

Deployment Steps

1. Deploy contract to Stacks network
2. Initialize bridge
3. Add initial validators
4. Verify bridge status

Security Considerations

• Keep private keys secure
• Regular validation of bridge state
• Monitor transaction confirmations
• Regular security audits recommended

License

This smart contract is released under the MIT License. See the LICENSE file for details.

Contact

For bug reports and feature requests, please open an issue in the repository.