Proposal for the Development of a Scroll-BTC Cross-Chain Bridge

[COINsciencer]

Name of the project

Proposal for the Development of a Scroll-BTC Cross-Chain Bridge

Project abstract

Abstract: This proposal outlines the development plan for a cross-chain bridge between the Scroll blockchain and the Bitcoin blockchain. The aim is to enable seamless interoperability and asset transfer between Scroll's ecosystem and the Bitcoin network. The bridge will facilitate the transfer of assets in a secure, trustless, and decentralized manner, ensuring the integrity and reliability of transactions across both chains.

Specification

Introduction: As the blockchain ecosystem continues to expand, the need for interoperability between different chains becomes increasingly apparent. This proposal addresses this need by focusing on the development of a cross-chain bridge between Scroll and Bitcoin, two prominent blockchains in the crypto space.

Technical Details:

Bridge Architecture: The bridge will be based on a federated peg design, utilizing a network of validators to confirm transactions and ensure consensus between the two chains.

Smart Contract Development: Smart contracts will be developed to manage the locking and unlocking of assets on both chains. These contracts will ensure the security and transparency of transactions.

Hash Time Locked Contracts (HTLCs): HTLCs will be implemented to enable atomic swaps between Scroll and Bitcoin, ensuring that transactions either occur completely or not at all.

Oracles Integration: Oracles will be utilized to provide real-time data about transactions and asset prices, ensuring accurate and timely execution of cross-chain transactions.

Security Measures: Robust security measures, including multi-signature schemes and threshold signatures, will be implemented to safeguard against potential attacks and ensure the integrity of the bridge.

Development Timeline:

Research and Planning Phase: Conduct research on existing cross-chain solutions and finalize the design of the bridge - 2 months.

Smart Contract Development: Develop and audit the smart contracts required for asset locking and unlocking - 2 months.

Bridge Implementation: Build the bridge infrastructure, including the federated peg and validator network - 3 months.

Integration and Testing: Integrate the bridge with both the Scroll and Bitcoin blockchains and conduct thorough testing - 2 months.

Deployment and Maintenance: Deploy the bridge into production and establish protocols for ongoing maintenance and upgrades - Ongoing.

Conclusion: The development of a Scroll-BTC cross-chain bridge holds significant promise for enhancing the interoperability and usability of both blockchains. By enabling seamless asset transfer between Scroll and Bitcoin, this bridge will unlock new opportunities for users and developers within the crypto ecosystem. We believe that this proposal lays a solid foundation for the successful implementation of the bridge and look forward to collaborating with the community to bring this vision to fruition.

[COINsciencer]

https://github.com/COINsciencer/contribute-to-scroll/blob/main/crossbtc.py

[COINsciencer]

// SPDX-License-Identifier: MIT pragma solidity ^0.8.0;

// Interface for the BTC Bridge contract interface IBTCBridge { function lock(address recipient, uint256 amount) external payable; function getLockedBalance(address recipient) external view returns(uint256); function unlock(uint256 amount) external; }

// BRC20 Bridge contract contract BRC20Bridge { address public btcBridgeAddress; // Address of the BTC Bridge contract address public owner; // Owner of the contract uint256 public totalLockedBRC20; // Total amount of BRC20 tokens locked in the bridge

// Mapping to track locked balances of users
mapping(address => uint256) public lockedBalances;

// Events
event TokensLocked(address indexed sender, address indexed recipient, uint256 amount);
event TokensUnlocked(address indexed recipient, uint256 amount);

// Modifier to ensure that only the owner can call certain functions
modifier onlyOwner() {
    require(msg.sender == owner, "Only owner can call this function");
    _;
}

// Constructor to set the BTC Bridge address and contract owner
constructor(address _btcBridgeAddress) {
    btcBridgeAddress = _btcBridgeAddress;
    owner = msg.sender;
}

// Function to lock BRC20 tokens and trigger BTC transfer
function lockBRC20(address recipient, uint256 amount) external {
    require(amount > 0, "Amount must be greater than 0");

    // Transfer BRC20 tokens to this contract
    // Assuming ERC20 transfer is approved beforehand
    // ERC20Token.transferFrom(msg.sender, address(this), amount);

    // Increase the locked balance of the recipient
    lockedBalances[recipient] += amount;
    totalLockedBRC20 += amount;

    // Emit event
    emit TokensLocked(msg.sender, recipient, amount);

    // Call the lock function of the BTC Bridge contract
    IBTCBridge btcBridge = IBTCBridge(btcBridgeAddress);
    btcBridge.lock{value: msg.value}(recipient, amount);
}

// Function to unlock BRC20 tokens upon receiving BTC on the other chain
function unlockBRC20(uint256 amount) external {
    require(amount > 0, "Amount must be greater than 0");

    // Ensure that the sender has enough locked balance
    require(lockedBalances[msg.sender] >= amount, "Insufficient locked balance");

    // Call the unlock function of the BTC Bridge contract
    IBTCBridge btcBridge = IBTCBridge(btcBridgeAddress);
    btcBridge.unlock(amount);

    // Decrease the locked balance of the sender
    lockedBalances[msg.sender] -= amount;
    totalLockedBRC20 -= amount;

    // Emit event
    emit TokensUnlocked(msg.sender, amount);

    // Transfer unlocked BRC20 tokens back to the sender
    // ERC20Token.transfer(msg.sender, amount);
}

// Function to get the locked balance of a user
function getLockedBalance(address user) external view returns(uint256) {
    return lockedBalances[user];
}

// Function to set the address of the BTC Bridge contract (only callable by the owner)
function setBTCBridgeAddress(address _btcBridgeAddress) external onlyOwner {
    btcBridgeAddress = _btcBridgeAddress;
}

// Function to withdraw any accumulated Ether (only callable by the owner)
function withdrawETH(uint256 amount) external onlyOwner {
    require(address(this).balance >= amount, "Insufficient contract balance");
    payable(owner).transfer(amount);
}

// Fallback function to receive Ether
receive() external payable {}

} This version of the contract includes the following additional features:

Total Locked Balance Tracking: Keeps track of the total amount of BRC20 tokens locked in the bridge. Individual User Balances: Utilizes a mapping to track the locked balances of individual users. Events: Emits events when tokens are locked and unlocked. Unlock Functionality: Provides a function for users to unlock their BRC20 tokens upon receiving BTC on the other chain. Get Locked Balance Function: Allows users to query their locked balance. Fallback Function: Enables the contract to receive Ether sent directly to it.

[COINsciencer]

`from bitcoinlib.wallets import HDWallet from bitcoinlib.transactions import P2shAddress from bitcoinlib.encoding import to_bytes from bitcoinlib.networks import set_network from bitcoinlib.services.services import BitcoinServiceBase from threading import Thread import requests import time

Set Bitcoin network parameters

set_network('mainnet')

Bitcoin HD wallet configuration

mnemonic = 'your_mnemonic_phrase' wallet = HDWallet.create('wallet1', keys=mnemonic, network='mainnet')

Bitcoin RPC configuration

rpc_user = 'your_rpc_username' rpc_password = 'your_rpc_password' rpc_ip = '127.0.0.1' rpc_port = '8332'

Ethereum RPC configuration

eth_rpc_url = 'your_ethereum_rpc_url'

BRC20 token contract address

brc20_contract_address = '0x123456789ABCDEF'

Bitcoin service class

class BitcoinService(BitcoinServiceBase): def init(self, *args, *kwargs): super().init(args, **kwargs)

# Listen for new blocks
def poll_blocks(self):
    while True:
        try:
            # Get the latest block height
            current_block_height = self.rpc.getblockcount()

            # If it's not the latest block, get the new block information
            if self.last_block_height != current_block_height:
                self.last_block_height = current_block_height

                # Process the new block
                self.process_block(current_block_height)

        except Exception as e:
            print(f"Error polling blocks: {e}")

        time.sleep(10)  # Poll every 10 seconds

# Process new block
def process_block(self, block_height):
    block_hash = self.rpc.getblockhash(block_height)
    block = self.rpc.getblock(block_hash)

    # Process each transaction in the block
    for txid in block['tx']:
        self.process_transaction(txid)

# Process transaction
def process_transaction(self, txid):
    transaction = self.rpc.getrawtransaction(txid, 1)

    # Check if the transaction matches the condition to trigger BRC20 token minting
    if your_condition(transaction):
        # Trigger BRC20 token minting on Ethereum
        mint_brc20_token(transaction)

Function to mint BRC20 token on Ethereum

def mint_brc20_token(transaction):

Call Ethereum RPC to trigger BRC20 token minting

# Example:
# payload = {
#     "jsonrpc": "2.0",
#     "method": "eth_sendTransaction",
#     "params": [{
#         "from": "your_ethereum_address",
#         "to": brc20_contract_address,
#         "data": "0x...encoded_data_for_minting...",
#         "gas": "0x...gas_limit...",
#         "gasPrice": "0x...gas_price..."
#     }],
#     "id": 1
# }
# response = requests.post(eth_rpc_url, json=payload)
# print(response.json())
print("Minting BRC20 token on Ethereum...")

Function to check if transaction meets the condition to trigger BRC20 token minting

def your_condition(transaction):

Add your condition logic here

# For example, check if BTC transaction amount exceeds a certain threshold
return True

Instantiate Bitcoin service class

bitcoin_service = BitcoinService(rpc_ip, rpc_port, rpc_user, rpc_password) bitcoin_service.start()

Start block listening thread

block_listener_thread = Thread(target=bitcoin_service.poll_blocks) block_listener_thread.start() `

[COINsciencer]

Below is an integrated Python code example that includes both the Bitcoin (BTC) and Ethereum Virtual Machine (EVM) parts for implementing a cross-chain bridge. This code listens for transactions on the Bitcoin network and triggers the minting of BRC20 tokens on Ethereum if certain conditions are met.