using System;

using System.Text;

using System.Dynamic;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Security.Cryptography;

using System.Web;

public class Program

{

    public static void Main()

    {

        var signablerequest = FormatRequest();

        var hmacSignature =  GenerateHmacSignature("e914a17c10c8b9fc892c4b5f9343da08f3d62f6f7023e85d7ecf6c6324cfa278", signablerequest, null, null);

        Console.WriteLine(signablerequest);

        Console.WriteLine(hmacSignature);

    }

     public static string FormatRequest()

        {

            dynamic request = new ExpandoObject();

            request.nonce = "f7360a0e-e39e-4049-bef5-53fbacf8c8dd";

            request.epochUtcTime = null;

            request.RequestedAmount = "1000";

            request.SecureCoAccountId = "cli20p51qqbp";

            request.RequestType = "semafone";

            request.OrderNumber = "123";

            request.FirstName = "Test";

            request.LastName = "User";

            request.RequestID = "738126f1-7eca-409d-be96-119f26831a6c";

            request.TransactionType = "purchase";

            request.SemafoneCrn = null;

            request.SemafoneSessionID = null;

            request.SemafoneEndpoint = null;

            request.BearerToken = "2cba1b8040e09040d7730f16a7851b3f";

            request.Token = "token_from_Yaml";

            request.AgentID = "Agent Fred";

​

            /*if (hppRequest?.RequestType.ToLower() == "ecommerce")

            {

                request.SuccessCallbackUrl = null;

                request.ErrorCallbackUrl = null;

                request.SuccessCallbackUrl = null;

            }

            else

            {

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

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

                {

                    request.SuccessCallbackUrl = null;

                }

                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 = 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);

        }

     //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();

        }

​

        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);

        }

}