CRsaBcmathProvider::GCD

static function GCD($e, $m) 
{
	$e1 = $e;
	$m1 = $m;
	while(bccomp($e1, 0) != 0) 
	{
		$w = bcsub($m1, bcmul($e1, bcdiv($m1, $e1, 0)));;
		$m1 = $e1;
		$e1 = $w;
	}

	return $m1;
}