01.check-in @Greeter
2023-06-29 15:50:13 # 02.ChainflagCTF

check-in(Greeter)

contract

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pragma solidity 0.8.7;

contract Greeter {
string greeting;

constructor(string memory _greeting) public {
greeting = _greeting;
}

function greet() public view returns (string memory) {
return greeting;
}

function setGreeting(string memory _greeting) public {
greeting = _greeting;
}

function isSolved() public view returns (bool) {
string memory expected = "HelloChainFlag";
return keccak256(abi.encodePacked(expected)) == keccak256(abi.encodePacked(greeting));
}
}

analyses

To make isSolved() returns true, we should modify greeting to “HelloChainFlag”. So we call setGreeting() with “HelloChainFlag” and then it will be solved.