VALIDATION DE CARTE DE CREDIT

function cc_validate($cc_num, $cc_type) {
	$mc_mask = array(1 => '51', 2 => '52', 3 => '53', 4 => '54', 5 => '55');
	$mc_len = array(1 => 16);
	$visa_mask = array(1 => '4');
	$visa_len = array(1 => 13, 2 => 16);
	$amex_mask = array(1 => '34', 2 => '37');
	$amex_len = array(1 => 15);
	$disc_mask = array(1 => '6001');
	$disc_len = array(1 => 16);
	$jcb_mask = array(1 => '3', 2 => '1800', 3 => '2131');
	$jcb_len = array(1 => 15, 2 => 16);

	$cc_mask = array();
	$cc_len = array();
	$cc_valid = false;

	/* STEP 1 VALIDER LEN + PREFIX */
	switch ($cc_type) {
		case 'mc':
			$cc_mask = $mc_mask;
			$cc_len = $mc_len;
			break;
		case 'visa':
			$cc_mask = $visa_mask;
			$cc_len = $visa_len;
			break;
		case 'amex':
			$cc_mask = $amex_mask;
			$cc_len = $amex_len;
			break;
		case 'disc':
			$cc_mask = $disc_mask;
			$cc_len = $disc_len;
			break;
		case 'jcb':
			$cc_mask = $jcb_mask;
			$cc_len = $jcb_len;
			break;
		default:
			die('Error, please go back');
	}
	$i = 1;
	while ((isset($cc_mask[$i]))&&(!empty($cc_mask[$i]))&&(!$cc_valid)) {
		$l = strlen($cc_mask[$i]);
		$cc_valid = (substr($cc_num, 0, $l)==$cc_mask[$i]);
		$i++;
	}
	if (!$cc_valid) { return false; }
	$i = 1; $cc_valid = false;
	while ((isset($cc_len[$i]))&&(!empty($cc_len[$i]))&&(!$cc_valid)) {
		$cc_valid = (strlen($cc_num)==$cc_len[$i]);
		$i++;
	}
	if (!$cc_valid) { return false; }
	$cc_valid = false;
	
	/* STEP 2 DOUBLE CHAQUES 2 DE 2 ET CHECK MOD 10 */
	$cc_num = strrev($cc_num);

	$num_sum = "";
	for($i = 0; $i < strlen($cc_num); $i++) {
		$cur_num = substr($cc_num, $i, 1);

		if($i % 2 == 1) {
			$cur_num *= 2;
		} if($cur_num > 9) {
			$f_num = $cur_num % 10;
			$s_num = ($cur_num - $f_num) / 10;
			$cur_num = $f_num + $s_num;
		}
		$num_sum += $cur_num;
	}
	$cc_valid = ($num_sum % 10 == 0);
	return $cc_valid;
}
?>