27 lines
899 B
Solidity
27 lines
899 B
Solidity
/*
|
|
* @source: https://github.com/SmartContractSecurity/SWC-registry/blob/master/test_cases/weak_randomness/random_number_generator.sol
|
|
* @author: -
|
|
* @vulnerable_at_lines: 12,18,20,22
|
|
*/
|
|
|
|
pragma solidity ^0.4.25;
|
|
|
|
// Based on TheRun contract deployed at 0xcac337492149bDB66b088bf5914beDfBf78cCC18.
|
|
contract RandomNumberGenerator {
|
|
// <yes> <report> BAD_RANDOMNESS
|
|
uint256 private salt = block.timestamp;
|
|
|
|
function random(uint max) view private returns (uint256 result) {
|
|
// Get the best seed for randomness
|
|
uint256 x = salt * 100 / max;
|
|
// <yes> <report> BAD_RANDOMNESS
|
|
uint256 y = salt * block.number / (salt % 5);
|
|
// <yes> <report> BAD_RANDOMNESS
|
|
uint256 seed = block.number / 3 + (salt % 300) + y;
|
|
// <yes> <report> BAD_RANDOMNESS
|
|
uint256 h = uint256(blockhash(seed));
|
|
// Random number between 1 and max
|
|
return uint256((h / x)) % max + 1;
|
|
}
|
|
}
|