Random::getStringByCharsets

static function getStringByCharsets($length, $charsetList)
{
	$charsetVariants = strlen($charsetList);
	$randomSequence = static::getBytes($length);

	$result = '';
	for ($i = 0; $i < $length; $i++)
	{
		$randomNumber = ord($randomSequence[$i]);
		$result .= $charsetList[$randomNumber % $charsetVariants];
	}
	return $result;
}