13.Fuzzy identity
2023-06-23 20:22:15 # 01.Capturetheether CTF

Fuzzy identity

topic

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pragma solidity ^0.4.21;

interface IName {
function name() external view returns (bytes32);
}

contract FuzzyIdentityChallenge {
bool public isComplete;

function authenticate() public {
require(isSmarx(msg.sender));
require(isBadCode(msg.sender));

isComplete = true;
}

function isSmarx(address addr) internal view returns (bool) {
return IName(addr).name() == bytes32("smarx");
}

function isBadCode(address _addr) internal pure returns (bool) {
bytes20 addr = bytes20(_addr);
bytes20 id = hex"000000000000000000000000000000000badc0de";
bytes20 mask = hex"000000000000000000000000000000000fffffff";

for (uint256 i = 0; i < 34; i++) {
if (addr & mask == id) {
return true;
}
mask <<= 4;
id <<= 4;
}

return false;
}
}

analyses

the same as the article in my blog: [security-04]

solution

the same as the article in my blog: [security-04]