PHP は、あらゆる種類のクレジット カード検証の原則を実装します。

<?php
// Plug-in 32: Validate Credit Card
// This is an executable example with additional code supplied
// To obtain just the plug-ins please click on the Download link
$card  = "4567 1234 5678 9101";
$exp  = "06/11";
echo "Validating: $card : $exp<br>";
$result = PIPHP_ValidateCC($card, $exp);
if ($result != FALSE) echo "Card Validated";
else echo "Card did not validate";
function PIPHP_ValidateCC($number, $expiry)
{
  // Plug-in 32: Validate Credit Card
  //
  // This plug-in accepts a credit card number and
  // an expiry date and returns TRUE or FALSE,
  // depending on whether the details pass date
  // and checksum validation. The arguments required
  // are:
  //
  //  $number: Credit Card Number
  //  $expiry: Expiry date in the form:
  //    07/12 or 0712 (for July, 2012)
  $number = preg_replace(&#39;/[^\d]/&#39;, &#39;&#39;, $number);
  $expiry = preg_replace(&#39;/[^\d]/&#39;, &#39;&#39;, $expiry);
  $left  = substr($number, 0, 4);
  $cclen = strlen($number);
  $chksum = 0;
  // Diners Club
  if (($left >= 3000) && ($left <= 3059) ||
    ($left >= 3600) && ($left <= 3699) ||
    ($left >= 3800) && ($left <= 3889))
   if ($cclen != 14) return FALSE;
  // JCB
  if (($left >= 3088) && ($left <= 3094) ||
    ($left >= 3096) && ($left <= 3102) ||
    ($left >= 3112) && ($left <= 3120) ||
    ($left >= 3158) && ($left <= 3159) ||
    ($left >= 3337) && ($left <= 3349) ||
    ($left >= 3528) && ($left <= 3589))
   if ($cclen != 16) return FALSE;
  // American Express
  elseif (($left >= 3400) && ($left <= 3499) ||
      ($left >= 3700) && ($left <= 3799))
   if ($cclen != 15) return FALSE;
  // Carte Blanche
  elseif (($left >= 3890) && ($left <= 3899))
   if ($cclen != 14) return FALSE;
  // Visa
  elseif (($left >= 4000) && ($left <= 4999))
   if ($cclen != 13 && $cclen != 16) return FALSE;
  // MasterCard
  elseif (($left >= 5100) && ($left <= 5599))
   if ($cclen != 16) return FALSE;
  // Australian BankCard
  elseif ($left == 5610)
   if ($cclen != 16) return FALSE;
  // Discover
  elseif ($left == 6011)
   if ($cclen != 16) return FALSE;
  // Unknown
  else return FALSE;
  for ($j = 1 - ($cclen % 2); $j < $cclen; $j += 2)
   $chksum += substr($number, $j, 1);
  for ($j = $cclen % 2; $j < $cclen; $j += 2)
  {
   $d = substr($number, $j, 1) * 2;
   $chksum += $d < 10 ? $d : $d - 9;
  }
  if ($chksum % 10 != 0) return FALSE;
  if (mktime(0, 0, 0, substr($expiry, 0, 2), date("t"),
   substr($expiry, 2, 2)) < time()) return FALSE;
  return TRUE;
}
?>