Credit Card Verification

From CDYNE Wiki for Web Services
Jump to: navigation, search

Verify a Credit Card for free by cross referencing it against the Luhn formula. This formula does not check with the major Credit Card companies for validity, it merely checks the Credit Card number algorithm to make sure it is a valid number for the four major Credit Cards accepted worldwide. Please use a license key of '0' if consuming via Web Service. The Luhn formula can also be used to identify the type of card by the # entered.

Contents

Developer/Tester Information

WSDL
Testing URL

Pricing

FREE forever. Use the CDYNE Credit Card Verification Web Service or the raw code used to program this Web Service.

Download Credit Card Verification Web Service code examples

ASP
.NET VB
CFM
FLASH
JSP
PHP

Open Source

Below you can find the C# or VB version of the Credit Card Verification Web Service code using the Luhn Formula.

Luhn Definition

The Luhn algorithm or Luhn formula, also known as the "modulus 10" or "mod 10" algorithm, was developed in the 1960s as a method of validating identification numbers. It is a simple checksum formula used to validate a variety of account numbers, such as credit card numbers and Canadian Social Insurance Numbers. Much of its notoriety comes from credit card companies' adoption of it shortly after its creation in the late 1960s by IBM scientist Hans Peter Luhn (1896–1964).

Explanation of the Luhn's algorithm can be found here.

C# Source Code

using System;
 
/// <summary>
/// Summary description for CCVerifier
/// </summary>
public class CCVerifier
{
 
    public ReturnIndicator CheckCC(string CardNumber)
    {
        ReturnIndicator ri = new ReturnIndicator();
        ri.CardValid = false;
        
 
        byte[] number = new byte[16]; // number to validate
 
        // Remove non-digits
        int len = 0;
        for (int i = 0; i < CardNumber.Length; i++)
        {
            if (char.IsDigit(CardNumber, i))
            {
                if (len == 16) return ri; // number has too many digits
                number[len++] = byte.Parse(CardNumber[i].ToString());
            }
        }
 
        // Use Luhn Algorithm to validate
        int sum = 0;
        for (int i = len - 1; i >= 0; i--)
        {
            if (i % 2 == len % 2)
            {
                int n = number[i] * 2;
                sum += (n / 10) + (n % 10);
            }
            else
                sum += number[i];
        }
 
        ri.CardValid = (bool) (sum % 10 == 0);
        if ((ri.CardValid == true))
        {
            switch (CardNumber.Substring(0, 1))
            {
                case "3":
                    ri.CardType = "AMEX/Diners Club/JCB";
                    break;
                case "4":
                    ri.CardType = "VISA";
                    break;
                case "5":
                    ri.CardType = "MasterCard";
                    break;
                case "6":
                    ri.CardType = "Discover";
                    break;
                default:
                    ri.CardType = "Unknown";
                    break;
            }
        }
        else
        {
            ri.CardType = "NONE";
        }
        return ri;
    }
 
 
    public class ReturnIndicator
    {
        public string CardType;
        public bool CardValid;
    }
}

The original code below (at the bottom) is INCORRECT... this one is used and tested and reflects the C# above more


Dim theNumber As String = Misc.Strings.MakeAllNumeric(accountNumber) 'i.e. 1234-5678-9012-3452 = 1234567890123452 If String.IsNullOrEmpty(theNumber) Then Return False

'Process digits from right to left Dim sum As Int32 = 0 Dim theDigit As Int32 = 0 For i As Int32 = theNumber.Length - 1 To 0 Step -1

  theDigit = Convert.ToInt32(theNumber.Substring(i, 1)) 'GET THE DIGIT (starting from the right)
  'USE THE EVEN DIGIT on EVEN LEN CARDS; ODD DIGIT on ODD LENGTH CARDS
  'EXAMPLE: "even" len card number ending in xxx51908
  '           8 + (0*2) + 9 + (1*2)          
  'EXAMPLE: "odd" len card number 49927398716
  '           6 + (1*2) + 7 + (8*2) + 9 + (3*2)... you get the point... but see next line
  '           6 + 2     + 7 + (1+6) + 9 + 6.... see the "break apart" the 16 = 1 + 6
  If ((i Mod 2) = (theNumber.Length Mod 2)) Then
     'the product = (theDigit * 2)
     'example: 6*2 = 12 or 9*2 = 18 or 7*2 = 14
     ' OVER 9 THEN Break the digits up and add them together (eg. 18 becomes 1 + 8, 14 becomes 1 + 4)
     ' UNDER 10 THEN JUST ADD IT
     If (theDigit * 2) >= 10 Then
        sum += ((theDigit * 2) \ 10) + ((theDigit * 2) - 10)
     Else
        sum += (theDigit * 2)
     End If
  Else
     sum += theDigit
  End If

Next

'RETURN 10's COMPLIMENT Return ((sum Mod 10) = 0)


              • ORGINAL CODE ******

VB.Net Source Code

Public Class CreditCardLib
    Public Enum eCreditCardType
        Invalid = 0
        AMEX = 3
        Visa = 4
        MasterCard = 5
        Discover = 6
    End Enum
 
    Public Shared Function CheckCardNumber(ByVal CardNumber As String) As eCreditCardType
        Dim SingleChar As String
        Dim CharValue As Integer
        Dim RunningValue As Integer = 0
        Dim Result As eCreditCardType
 
        CardNumber = Replace(Replace(Replace(CStr(CardNumber), "-", String.Empty), " ", String.Empty), ".", String.Empty) 'Help ensure proper format of the input
        Dim NumberLen As Integer = Len(CardNumber)
 
        ' Default value
        Result = eCreditCardType.Invalid
        Select Case Left(CardNumber, 1)
            Case "3"
                'AMEX: 15 digit numbers starting with 34 or 37 
                If NumberLen = 15 And (Left(CardNumber, 2) = "34" Or Left(CardNumber, 2) = "37") Then
                    Result = eCreditCardType.AMEX
                End If
            Case "4"
                'Visa: 13 or 16 digit numbers starting with 4 
                If NumberLen = 13 Or NumberLen = 16 Then
                    Result = eCreditCardType.Visa
                End If
            Case "5"
                'MasterCard: 16 digit numbers starting with 5 
                If NumberLen = 16 Then
                    Result = eCreditCardType.MasterCard
                End If
            Case "6"
                'Discover: 16 digit numbers starting with 6011 or 65 
                If NumberLen = 16 And (Left(CardNumber, 4) = "6011" Or Left(CardNumber, 2) = "65") Then
                    Result = eCreditCardType.Discover
                End If
        End Select
 
        If Result <> eCreditCardType.Invalid Then
            'Process digits from right to left, drop last digit if total length is even
            Dim w As Integer = 2 * (NumberLen Mod 2)
            For i As Integer = NumberLen - 1 To 1 Step -1
                SingleChar = Mid(CardNumber, i, 1)
                If IsNumeric(SingleChar) Then
                    Select Case (i Mod 2) + w
                        Case 0, 3 'Even Digit - Odd where total length is odd (eg. Visa vs. Amx)
                            RunningValue += CInt(SingleChar)
                        Case 1, 2 'Odd Digit - Even where total length is odd (eg. Visa vs. Amx)
                            CharValue = CInt(SingleChar) * 2
                            If CharValue > 9 Then
                                'Break the digits (eg. 19 becomes 1 + 9)    
                                RunningValue += (CharValue \ 10) + (CharValue - 10)
                            Else
                                RunningValue += CharValue
                            End If
                    End Select
                End If
            Next
 
            'Return the 10's complement of the total
            RunningValue = 10 - (RunningValue Mod 10)
            If RunningValue > 9 Then
                RunningValue = 0
            End If
 
            ' Finally, check the checksum digit.  If it's invalid then we have an invalid card.
            If (CStr(RunningValue) <> Right(CardNumber, 1)) Then
                Result = eCreditCardType.Invalid
            End If
        End If
 
        Return Result
    End Function
End Class

PHP Example for Web Service

class CCVerify {
	private $CardNumber;
	public $response;
	
 	public function __construct($CardNumber) {
		$this->CardNumber = $CardNumber;
		$this->getResponse();
	}
	public function getResponse(){
		$url = "https://ws.cdyne.com/creditcardverify/luhnchecker.asmx";
		$url .= "/CheckCC?CardNumber=" . $this->CardNumber;
		$this->response = simplexml_load_file($url) or die("ERROR");
	}
 }
 $CardNumber = "123412341243124";
 $results = new CCVerify( $CardNumber );
 var_dump($results);
Personal tools
Toolbox





Trial Key