namespace MSAPI_ProcessTransaction
  {
  using System;
  using System.Collections.Generic;
  using System.IO;
  using System.Linq;
  using System.Net;
  using System.Text;
  using System.Xml;
  using System.Xml.Linq;
  using System.Xml.Serialization;

/*
  ProPay provides the following code “AS IS.”
ProPay makes no warranties and ProPay disclaims all warranties and conditions, express, implied or statutory,
  including without limitation the implied warranties of title, non-infringement, merchantability, and fitness for a particular purpose.
  ProPay does not warrant that the code will be uninterrupted or error free,
  nor does ProPay make any warranty as to the performance or any results that may be obtained by use of the code.
  */
  public class ProcessTransactionTransType300
  {
  public static void ProcessTransaction()
  {
  var processRequest = new XmlTransactionRequest { CertificationString = "YourCertStringGoesHere", TerminalID = "YourTermId", };
  var xmlTransaction = new XmlProcessTransaction
  {
  TransType = "300",
  accountNum = "12345678",
  ReferrerUrl = "www.myurl.com",
  IpAddress = "206.192.156.0",
  IpSubnetMask = "255.255.255.0",
  };
  processRequest.Transactions.Add(xmlTransaction);
  string request = XmlSerializer<XmlTransactionRequest>.WriteToString(processRequest);
  SubmitRequest(request);
  }

private static void SubmitRequest(string request)
  {
  byte[] dataToSend = Encoding.UTF8.GetBytes(request);

// Change the following URL to point to production instead of integration
  WebRequest webRequest = WebRequest.Create("https://xmltest.propay.com/API/PropayAPI.aspx");
  webRequest.Method = "POST";
  webRequest.ContentLength = dataToSend.Length;
  webRequest.ContentType = "text/xml";
  webRequest.Headers.Add("X509Certificate", GetBase64Cert(“your certificate thumbprint goes here”));
  webRequest.ProtocolVersion = HttpVersion.Version10;
  Stream dataStream = webRequest.GetRequestStream();
  dataStream.Write(dataToSend, 0, dataToSend.Length);
  dataStream.Close();

string response = string.Empty;

try
  {
  WebResponse apiResponse = webRequest.GetResponse();

using (StreamReader sr = new StreamReader(apiResponse.GetResponseStream()))
  {
  response += sr.ReadToEnd();
  }
  }
  catch (WebException wex)
  {
  HttpWebResponse httpResponse = wex.Response as HttpWebResponse;
  using (Stream responseStream = httpResponse.GetResponseStream())
  using (StreamReader reader = new StreamReader(responseStream))
  {
  response = reader.ReadToEnd();
  }
  }

 ParseResponse(response);
  }

private static void ParseResponse(string response)
  {
  var load = XDocument.Parse(response);
  var transType = Convert.ToInt32(load.Descendants().First(p => p.Name.LocalName == "transType").Value);
  var status = load.Descendants().First(p => p.Name.LocalName == "status").Value;
  var AuthToken = load.Descendants().First(p => p.Name.LocalName == "AuthToken").Value;
  }
  }

public class XmlProcessTransaction : XmlTransaction
  {
  [XmlElement("accountNum")]
  public string accountNum = string.Empty;
  [XmlElement("ReferrerUrl")]
  public string ReferrerUrl = string.Empty;
  [XmlElement("IpAddress")]
  public string IpAddress = string.Empty;
  [XmlElement("IpSubnetMask")]
  public string IpSubnetMask = string.Empty;
  }

public static class XmlSerializer<T>
  {
  public static XmlSerializer Serializer = new XmlSerializer(typeof(T));
  public static string WriteToString(T data)
  {
  return WriteToString(data, Encoding.UTF8);
  }
  public static string WriteToString(T data, Encoding encoding)
  {
  string retVal;
  using (MemoryStream memoryStream = new MemoryStream())
  {
  using (XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, encoding))
  {
  Serializer.Serialize(xmlTextWriter, data);
  }

retVal = encoding.GetString(memoryStream.ToArray());
  }

return retVal;
  }
  }

[XmlInclude(typeof(XmlProcessTransaction))]
  public class XmlTransaction
  {
  [XmlElement("transType")]
  public string TransType = string.Empty;
  }
  [XmlRoot("XMLRequest")]
  public class XmlTransactionRequest
  {
  [XmlElement("certStr")]
  public string CertificationString = string.Empty;
  [XmlElement("termid")]
  public string TerminalID = string.Empty;
  [XmlElement("XMLTrans")]
  public List<XmlTransaction> Transactions = new List<XmlTransaction>();
  }

public string GetBase64Cert(string certificateThumbprint)
 {
 using (X509Store store = new X509Store(StoreName.My, StoreLocation.LocalMachine))
 {
 store.Open(OpenFlags.ReadOnly);
 var foundCertificates = store.Certificates.Find(X509FindType.FindByThumbprint, certificateThumbprint, false);
 if (foundCertificates.Count != 1)
 {
 return null;
 }
 var certByteArray = foundCertificates[0].Export(X509ContentType.Cert);
 store.Close();
 return Convert.ToBase64String(certByteArray);
 }
}