using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Security.Cryptography;

using System.Text;

using System.Web;

using System.ComponentModel.DataAnnotations;

using System.Net;

​

public class Program

{

    public static void Main()

    {

        var nonce = Guid.NewGuid().ToString();

        var merchantAccountId = "EGate_SecureCoAccountId_Purchase";

        var hexKey = "c982b82023d29f27f112c2931739a31438fd9c44bd6b9877d851f9b47635797f"; // Replace with actual hex key

        //Buld the HPP request

        var hppRequest = new HPPRequest{

            BearerToken = "d08a2cc93a97ecc487645c1ac393a642", TransactionType = "purchase", SecureCoAccountId = merchantAccountId,

            RequestedAmount = "10.00", Token = "", RequestType = "semafone",

            RequestID =  Guid.NewGuid().ToString(), TransactionTimestamp = "3/07/2018 1:37:22 AM"

        };

        string hppMessage = FormatRequest(hppRequest);

        string httpSignature = GenerateHmacSignature(hexKey, hppMessage, null, nonce);

        hppRequest.SignatureHmac = httpSignature;

        hppRequest.SignatureNonce = nonce;

        Console.WriteLine("HMAC Details \n ");

        Console.WriteLine("Secret Key - " + hexKey + "\n ");

        Console.WriteLine("Message Signature - " + hppRequest.SignatureHmac + "\n ");

        Console.WriteLine("Nonce - " + hppRequest.SignatureNonce + "\n ");          

        Console.WriteLine("HPP Request - " + FormatRequest(hppRequest));

        // Post to HPP

        PostData(hppRequest);

    }

​

    public static string FormatRequest(HPPRequest hppRequest)

    {

        dynamic request = new System.Dynamic.ExpandoObject();

        request.RequestedAmount = hppRequest.RequestedAmount;

        request.SecureCoAccountId = hppRequest.SecureCoAccountId;

        request.RequestType = hppRequest.RequestType;

        request.OrderNumber = hppRequest.OrderNumber;

        request.FirstName = hppRequest.FirstName;

        request.LastName = hppRequest.LastName;

        request.RequestID = hppRequest.RequestID;

        request.TransactionType = hppRequest.TransactionType;

        request.SemafoneCrn = hppRequest.SemafoneCrn;

        request.SemafoneSessionID = hppRequest.SemafoneSessionID;

        request.SemafoneEndpoint = hppRequest.SemafoneEndpoint;

        request.BearerToken = hppRequest.BearerToken;

        request.Token = hppRequest.Token;

        request.AgentID = hppRequest.AgentID;

        request.SignatureHmac = hppRequest.SignatureHmac;

        request.SignatureNonce = hppRequest.SignatureNonce;

        if (hppRequest.RequestType.ToLower() == "ecommerce")

        {

            request.SuccessCallbackUrl = hppRequest.SuccessCallbackUrl;

            request.ErrorCallbackUrl = hppRequest.ErrorCallbackUrl;

            request.SuccessCallbackUrl = hppRequest.CancellationCallbackUrl;

        }

        else

        {

            // in semafone mode its optional to send all 3 callback urls

            if (!string.IsNullOrEmpty(hppRequest.SuccessCallbackUrl))

            {

                request.SuccessCallbackUrl = hppRequest.SuccessCallbackUrl;

            }

​

            if (!string.IsNullOrEmpty(hppRequest.ErrorCallbackUrl))

            {

                request.ErrorCallbackUrl = hppRequest.ErrorCallbackUrl;

            }

​

            if (!string.IsNullOrEmpty(hppRequest.CancellationCallbackUrl))

            {

                request.CancellationCallbackUrl = hppRequest.CancellationCallbackUrl;

            }

        }

​

        StringBuilder signableRequest = new StringBuilder();

        foreach (var property in (IDictionary<string, object>)request)

        {

            signableRequest.Append(property.Key + "=" + property.Value).Append("&");

        }

​

        return signableRequest.ToString().TrimEnd(new char[]{'&'});

    }

​

    public static string GenerateHmacSignature(string hexKey, string message, string epochUtcTime = null, string nonce = null)

    {

        if (String.IsNullOrEmpty(hexKey))

        {

            throw new Exception("HexKey is null or Empty.");

        }

​

        if (!IsValidHexString(hexKey))

        {

            throw new Exception("HexKey contains non-hexidecimal characters.");

        }

​

        //Convert Hexidecimal Key to Bytes

        byte[] byteKey = HexStringToByteArray(hexKey);

        //Verify Key Length

        if (byteKey.Length != 32 && byteKey.Length != 64)

            throw new Exception("Key length is not 256 or 512 bits");

        //BuildMessage

        var completeMessage = (String.IsNullOrEmpty(nonce) ? "nonce=&" : "nonce=" + HttpUtility.UrlEncode(nonce) + "&") + (String.IsNullOrEmpty(epochUtcTime) ? "epochUtcTime=&" : "epochUtcTime=" + HttpUtility.UrlEncode(epochUtcTime) + "&") + message;

        byte[] hashValue;

        // Initialize the keyed hash object.

        using (HMACSHA256 hmac = new HMACSHA256(byteKey))

        {

            //Use a Mmeorystream to apas into the keyed hash object.

            using (MemoryStream inStream = new MemoryStream(Encoding.UTF8.GetBytes(completeMessage)))

            {

                // Compute the hash of the input message.

                hashValue = hmac.ComputeHash(inStream);

            }

        }

​

        return ByteArrayToHexString(hashValue);

    }

​

    private static bool IsValidHexString(IEnumerable<char> hexString)

    {

        return hexString.Select(currentCharacter => (currentCharacter >= '0' && currentCharacter <= '9') || (currentCharacter >= 'a' && currentCharacter <= 'f') || (currentCharacter >= 'A' && currentCharacter <= 'F')).All(isHexCharacter => isHexCharacter);

    }

​

    //Crypto Helper Class.

    public static byte[] HexStringToByteArray(String hex)

    {

        int NumberChars = hex.Length;

        byte[] bytes = new byte[NumberChars / 2];

        for (int i = 0; i < NumberChars; i += 2)

            bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);

        return bytes;

    }

​

    public static string ByteArrayToHexString(byte[] ba)

    {

        StringBuilder hex = new StringBuilder(ba.Length * 2);

        foreach (byte b in ba)

            hex.AppendFormat("{0:x2}", b);

        return hex.ToString();

    }

    public static void PostData(HPPRequest hppRequest){

        // Create a request using a URL that can receive a post.   

            WebRequest request = WebRequest.Create ("http://sandbox-payments.secureco.co/home/");  

            // Set the Method property of the request to POST.  

            request.Method = "POST";  

            // Create POST data and convert it to a byte array.  

            string postData = FormatRequest(hppRequest);  

            byte[] byteArray = Encoding.UTF8.GetBytes (postData);  

            // Set the ContentType property of the WebRequest.  

            request.ContentType = "application/x-www-form-urlencoded";  

            // Set the ContentLength property of the WebRequest.  

            request.ContentLength = byteArray.Length;  

            // Get the request stream.  

            Stream dataStream = request.GetRequestStream ();  

            // Write the data to the request stream.  

            dataStream.Write (byteArray, 0, byteArray.Length);  

            // Close the Stream object.  

            dataStream.Close ();  

            // Get the response.  

            WebResponse response = request.GetResponse ();  

            // Display the status.  

            Console.WriteLine (((HttpWebResponse)response).StatusDescription);  

            // Get the stream containing content returned by the server.  

            dataStream = response.GetResponseStream ();  

            // Open the stream using a StreamReader for easy access.  

            StreamReader reader = new StreamReader (dataStream);  

            // Read the content.  

            string responseFromServer = reader.ReadToEnd ();  

            // Display the content.  

            Console.WriteLine (responseFromServer);  

            // Clean up the streams.  

            reader.Close ();  

            dataStream.Close ();  

    }

}

​

public class HPPRequest

{

    public string OrderNumber

    {

        get;

        set;

    }

​

    public string RequestedAmount

    {

        get;

        set;

    }

​

    [Required(ErrorMessage = "SecureCo AccountID  is required")]

    public string SecureCoAccountId

    {

        get;

        set;

    }

​

    [Required(ErrorMessage = "RequestID is required")]

    public string RequestID

    {

        get;

        set;

    }

​

    [Required(ErrorMessage = "Transaction Type is required")]

    public string TransactionType

    {

        get;

        set;

    }

​

    public string TransactionTimestamp

    {

        get;

        set;

    }

​

    public string FirstName

    {

        get;

        set;

    }

​

    public string LastName

    {

        get;

        set;

    }

​

    public string LogoUri

    {

        get;

        set;

    }

​

    public string SiteName

    {

        get;

        set;

    }

​

    public string SuccessCallbackUrl

    {

        get;

        set;

    }

​

    public string CancellationCallbackUrl

    {

        get;

        set;

    }

​

    public string ErrorCallbackUrl

    {

        get;

        set;

    }

​

    [Required(ErrorMessage = "Request Type is required")]

    public string RequestType

    {

        get;

        set;

    }

​

    public string SignatureHmac

    {

        get;

        set;

    }

​

    public string SignatureNonce

    {

        get;

        set;

    }

​

    public string BearerToken

    {

        get;

        set;

    }

​

    public string PostbackUrl

    {

        get;

        set;

    }

​

    public bool IsHmacGenerated

    {

        get;

        set;

    }

​

    [Required(ErrorMessage = "Hmac Key is required")]

    public string HmacKey

    {

        get;

        set;

    }

​

    public bool SkipCVC

    {

        get;

        set;

    }

​

    public string Token

    {

        get;

        set;

    }

​

    public string SemafoneCrn

    {

        get;

        set;

    }

​

    public string SemafoneSessionID

    {

        get;

        set;

    }

​

    public string SemafoneEndpoint

    {

        get;

        set;

    }

​

    public string AgentID

    {

        get;

        set;

    }

}