## Overview
Bitlayer is developing Bitlayer BitVM Bridge based on [BitVM2](https://bitvm.org/bitvm_bridge.pdf) and is currently in the audit phase. We are seeking to establish partnerships with audit service providers.

You can gain a comprehensive understanding of Bitlayer BitVM Bridge architecture by reading this [blog](https://blog.bitlayer.org/introducing_finality_bridge/).

We look forward to further discussions on the audit scope, requirements, service fees, and payment methods.
## Scope
The code is divided into two repos:
### BTC Smart Contracts
- Code Repository: https://github.com/bitlayer-org/bitvm-bridge/tree/final_version_for_audit
- Audit scope:
crates/protocol/transactions/src/\*.rs
crates/protocol/transactions/src/utils/\*.rs
crates/protocol/bridge-defender/src/\*.rs
crates/protocol/primitives/src/\*.rs

This part defines the Bitcoin transaction construction for bridge

The diagram below outlines the lifecycle of a Bitcoin bridging process:
Different colored dashed boxes represent the presigning actions of different roles and the scope of their presigned transactions.
### ETH Smart Contracts
- Code Repository: https://github.com/bitlayer-org/bitvm-bridge-contracts/tree/audit
- Audit scope:
contracts/ethereum/\*.sol* (No Proxy.sol)
contracts/ethereum/lib/\*.sol

These contract contains the core logic of the Peg BTC bridge, including the Bitcoin Pegin (locking BTC and minting equivalent YBTC tokens on Ethereum) and Pegout (burning YBTC and unlocking BTC for users) operations.
## Note
Since these two parts are closely interconnected in terms of system logic, we hope they won’t be audited as completely separate components. Auditing them together will help identify potential issues more effectively.