public function testHashLength()
{
if (MWCryptHash::hashAlgo() !== 'whirlpool') {
$this->markTestSkipped('Hash algorithm isn\'t whirlpool');
}
$this->assertEquals(64, MWCryptHash::hashLength(), 'Raw hash length');
$this->assertEquals(128, MWCryptHash::hashLength(false), 'Hex hash length');
}
/**
* Randomly hash data while mixing in clock drift data for randomness
*
* @param string $data The data to randomly hash.
* @return string The hashed bytes
* @author Tim Starling
*/
protected function driftHash($data)
{
// Minimum number of iterations (to avoid slow operations causing the
// loop to gather little entropy)
$minIterations = self::MIN_ITERATIONS;
// Duration of time to spend doing calculations (in seconds)
$duration = self::MSEC_PER_BYTE / 1000 * MWCryptHash::hashLength();
// Create a buffer to use to trigger memory operations
$bufLength = 10000000;
$buffer = str_repeat(' ', $bufLength);
$bufPos = 0;
// Iterate for $duration seconds or at least $minIterations number of iterations
$iterations = 0;
$startTime = microtime(true);
$currentTime = $startTime;
while ($iterations < $minIterations || $currentTime - $startTime < $duration) {
// Trigger some memory writing to trigger some bus activity
// This may create variance in the time between iterations
$bufPos = ($bufPos + 13) % $bufLength;
$buffer[$bufPos] = ' ';
// Add the drift between this iteration and the last in as entropy
$nextTime = microtime(true);
$delta = (int) (($nextTime - $currentTime) * 1000000);
$data .= $delta;
// Every 100 iterations hash the data and entropy
if ($iterations % 100 === 0) {
$data = sha1($data);
}
$currentTime = $nextTime;
$iterations++;
}
$timeTaken = $currentTime - $startTime;
$data = MWCryptHash::hash($data);
wfDebug(__METHOD__ . ": Clock drift calculation " . "(time-taken=" . $timeTaken * 1000 . "ms, " . "iterations={$iterations}, " . "time-per-iteration=" . $timeTaken / $iterations * 1000000.0 . "us)\n");
return $data;
}