4D Payments SDK 2016 .NET Edition

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KSN Property

Clear-text Key Sequence Number retrieved from a PIN pad.


public string KSN { get; set; }
Public Property KSN As String

Default Value



A 19 or 20-byte Key Sequence Number (KSN) and associated EncryptedPIN are required for all debit Sale and Credit transactions. These values must be retrieved from a certified DUKPT DES pin pad device. A 20-byte Key Sequence Number consists of a 1-byte pad character ('F'), a 9-byte Base Derivation Key Id (BDK ID), a 5-byte device Id, and a 5-byte transaction counter. If this property is set with a Key Sequence Number less than 20 bytes in length, the component will pad it on the left with 'F' characters.

The EncryptedPIN and KSN are not required for ReverseLastTransaction transactions.

The following code snippet shows how to send a simple debit sale transaction with all required properties.

  FDMSDebit1.MerchantNumber = "YOURNUMBER"
  FDMSDebit1.MerchantTerminalNumber = "YOURTERMID"
  FDMSDebit1.DatawireId = "YOURDID"
  FDMSDebit1.URL = "https://staging1.datawire.net/sd"; // test server
  FDMSDebit1.TransactionNumber = 4;
  FDMSDebit1.TransactionAmount = "100";
  FDMSDebit1.Card.EntryDataSource = edsTrack2;
  FDMSDebit1.Card.MagneticStripe = "9876543210012341234=12041200000001"; // (pin 1234)
  FDMSDebit1.EncryptedPIN = "0082943935BA205D";
  FDMSDebit1.KSN = "8765432109003000012";
  FDMSDebit1.ReceiptNumber = "123456";
If the transaction is successful, the ApprovalCode will start with "AP", and the CaptureFlag will be true. Even though debit transactions are on-line transactions, it is still necessary to settle them with First Data. The following example shows how to send a simple settlement. The first thing to do is to set up the FDMSSettle component's properties with the same information used for the debit sale:
  FDMSSettle1.MerchantNumber = FDMSDebit1.MerchantNumber;
  FDMSSettle1.MerchantTerminalNumber = FDMSDebit1.MerchantTerminalNumber;
  FDMSSettle1.DatawireId = FDMSDebit1.DatawireId;
  FDMSSettle1.URL = FDMSDebit1.URL;
  FDMSSettle1.MerchantServiceNumber = "8001234567";
  FDMSSettle1.BatchSequenceNumber = "101";  
  FDMSSettle1.IndustryType = itRetail;
Then all that needs to be done is add the detail record from the debit sale to the settlement component and call the SendSettlement method.
  FDMSSettle1.DetailRecords.Add(new FDMSRecordType(FDMSDebit1.GetDetailAggregate());
Note that in a live system you would store detail records in a database and send multiple records in a single batch at the end of the business day.

Copyright (c) 2021 4D Payments Inc. - All rights reserved.
4D Payments SDK 2016 .NET Edition - Version 16.0 [Build 7809]