/// <summary>
 /// Every time is created new instance of class to guarantee thread safety
 /// </summary>
 /// <param name="function"></param>
 /// <returns></returns>
 private HMAC GetAlgorithmByFunctionName(string function)
 {
     HMAC a;
     switch(Util.Convertion.EnumNameToValue<HMACFunction>(function))
     {
         case HMACFunction.HMACMD5:
             a = new HMACMD5();
             break;
         case HMACFunction.HMACSHA1:
             a = new HMACSHA1();
             break;
         case HMACFunction.HMACSHA256:
             a = new HMACSHA256();
             break;
         case HMACFunction.HMACSHA384:
             a = new HMACSHA384();
             break;
         case HMACFunction.HMACSHA512:
             a = new HMACSHA512();
             break;
         default:
             throw new ArgumentException("Unknown function", "function");
     }
     return a;
 }

        public static string CryptoMD5(string TextToCryptograph)
        {
            var md5 = new HMACMD5();
            byte[] passwordArray = System.Text.Encoding.Default.GetBytes(TextToCryptograph);

            return Convert.ToBase64String(md5.ComputeHash(passwordArray));
        }

 // Decrypt the encoded file and compare to original file.
 /// <summary>
 /// 检查文件是否被篡改
 /// </summary>
 /// <param name="key"></param>
 /// <param name="sourceFile"></param>
 /// <returns>true文件与哈希值一致， false不一致</returns>
 public static bool DecodeFile(byte[] key, String sourceFile)
 {
     // Initialize the keyed hash object.
     HMACMD5 hmacMD5 = new HMACMD5(key);
     // Create an array to hold the keyed hash value read from the file.
     byte[] storedHash = new byte[hmacMD5.HashSize / 8];
     // Create a FileStream for the source file.
     FileStream inStream = new FileStream(sourceFile, FileMode.Open);
     // Read in the storedHash.
     inStream.Read(storedHash, 0, storedHash.Length);
     // Compute the hash of the remaining contents of the file.
     // The stream is properly positioned at the beginning of the content,
     // immediately after the stored hash value.
     byte[] computedHash = hmacMD5.ComputeHash(inStream);
     // compare the computed hash with the stored value
     for (int i = 0; i < storedHash.Length; i++)
     {
         if (computedHash[i] != storedHash[i])
         {
             Console.WriteLine("Hash values differ! Encoded file has been tampered with!");
             return false;
         }
     }
     Console.WriteLine("Hash values agree -- no tampering occurred.");
     return true;
 }

 public override ISaslStep Next(byte[] bytesReceived)
 {
     var kMd5 = new HMACMD5(Encoding.UTF8.GetBytes(_password));
     var computedHash = kMd5.ComputeHash(bytesReceived);
     var passwordHash = BitConverter.ToString(computedHash).ToLower().Replace("-", "");
     return new SecondStep(Encoding.UTF8.GetBytes(string.Concat(_userName, ' ', passwordHash)));
 }

        public string signMD5(Dictionary<string, string> paramDic, string SecurityKey, bool isContent = false)
        {
            byte[] signatureKey = Encoding.UTF8.GetBytes(SecurityKey);//此处用自己的签名密钥
            List<string> list = new List<string>();
            foreach (KeyValuePair<string, string> kv in paramDic)
            {
                if (kv.Key.ToLower() != "sign")
                    list.Add(kv.Key + kv.Value);
            }
            list.Sort();
            StringBuilder tmp = new StringBuilder();
            foreach (string kvstr in list)
            {
                tmp.Append(kvstr);
            }

            //HMAC-MD5
            HMACMD5 hmacmd5 = new HMACMD5(signatureKey);
            hmacmd5.ComputeHash(Encoding.UTF8.GetBytes(tmp.ToString()));
            /*
            hmacsha1.ComputeHash(Encoding.UTF8.GetBytes(urlPath));
            foreach (string kvstr in list)
            {
                hmacsha1.ComputeHash(Encoding.UTF8.GetBytes(kvstr));
            }
             */
            byte[] hash = hmacmd5.Hash;
            //TO HEX
            return BitConverter.ToString(hash).Replace("-", string.Empty).ToUpper();
        }

      public override byte[] EvaluateChallenge(byte[] challenge)
      {
        if ( challenge == null || challenge.Length == 0 )
            throw new ArgumentNullException("challenge");


        NameCallback nameCB = new NameCallback(AuthorizationId);
        PasswordCallback pwdCB = new PasswordCallback();
        ISaslCallback[] callbacks = { nameCB, pwdCB };
        Handler.Handle(callbacks);

        string username = nameCB.Text;
        
        //Encode the Hashed Password as Hex
        byte[] passwd = Encoding.UTF8.GetBytes(ToHex(pwdCB.HashedText));

        string s = System.Text.UTF8Encoding.UTF8.GetString(challenge);
        
        using ( HMAC hmac = new HMACMD5(passwd) )
         {
            byte[] value = hmac.ComputeHash(challenge);
            string encoded = ToHex(value);
            SetComplete();
            return Encoding.UTF8.GetBytes(username + " " + encoded);
         }
      }

        public bool ValidateResponse(string password)
        {
            HMACMD5 hmacmd5 = new HMACMD5(ASCIIEncoding.ASCII.GetBytes(password));
            string expectedResponse = BitConverter.ToString(hmacmd5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(Challenge))).Replace("-", "");

            return string.Equals(expectedResponse, ChallengeResponse, StringComparison.InvariantCultureIgnoreCase);
        }

        public static string ComputeHashDigest(string hashString, string preSharedKey, HashMethod hashMethod)
        {
            byte[] key = StringToByteArray(preSharedKey);
            byte[] data = StringToByteArray(hashString);

            byte[] hashDigest;

            switch (hashMethod)
            {
                case HashMethod.HMACMD5:
                    hashDigest = new HMACMD5(key).ComputeHash(data);
                    break;
                case HashMethod.HMACSHA1:
                    hashDigest = new HMACSHA1(key).ComputeHash(data);
                    break;
                case HashMethod.MD5:
                    hashDigest = new MD5CryptoServiceProvider().ComputeHash(data);
                    break;
                case HashMethod.SHA1:
                    hashDigest = new SHA1CryptoServiceProvider().ComputeHash(data);
                    break;
                default:
                    throw new InvalidOperationException("Invalid hash method");
            }

            return (ByteArrayToHexString(hashDigest));
        }

 // Computes a keyed hash for a source file, creates a target file with the keyed hash
 // prepended to the contents of the source file, then decrypts the file and compares
 // the source and the decrypted files.
 /// <summary>
 ///  文件加密
 /// </summary>
 /// <param name="key"></param>
 /// <param name="sourceFile">待加密的文件</param>
 /// <param name="destFile">加密后的文件</param>
 public static void EncodeFile(byte[] key, String sourceFile, String destFile)
 {
     // Initialize the keyed hash object.
     HMACMD5 myhmacMD5 = new HMACMD5(key);
     FileStream inStream = new FileStream(sourceFile, FileMode.Open);
     FileStream outStream = new FileStream(destFile, FileMode.Create);
     // Compute the hash of the input file.
     byte[] hashValue = myhmacMD5.ComputeHash(inStream);
     // Reset inStream to the beginning of the file.
     inStream.Position = 0;
     // Write the computed hash value to the output file.
     outStream.Write(hashValue, 0, hashValue.Length);
     // Copy the contents of the sourceFile to the destFile.
     int bytesRead;
     // read 1K at a time
     byte[] buffer = new byte[1024];
     do
     {
         // Read from the wrapping CryptoStream.
         bytesRead = inStream.Read(buffer, 0, 1024);
         outStream.Write(buffer, 0, bytesRead);
     } while (bytesRead > 0);
     myhmacMD5.Clear();
     // Close the streams
     inStream.Close();
     outStream.Close();
     return;
 }

        public byte[] Compute(int bytes, byte[] secret, string label, byte[][] seeds)
        {
            /* SEEDSを再構成 */
            byte[][] new_seeds = new byte[seeds.Length + 1][];
            new_seeds[0] = System.Text.Encoding.ASCII.GetBytes (label);
            for (int i = 0; i < seeds.Length; i ++)
                new_seeds[i + 1] = seeds[i];

            /* secretを分割 */
            byte[] S1 = new byte[secret.Length >> 1];
            byte[] S2 = new byte[secret.Length >> 1];
            Buffer.BlockCopy (secret, 0, S1, 0, S1.Length);
            Buffer.BlockCopy (secret, S1.Length, S2, 0, S2.Length);

            /* P_SHA1とP_MD5を計算 */
            byte[] pSHA1, pMD5;
            using (HMACSHA1 hmacSHA1 = new HMACSHA1 (S2, true))
            using (HMACMD5 hmacMD5 = new HMACMD5 (S1)) {
                pSHA1 = Compute_PHash (bytes, new_seeds, hmacSHA1, 20);
                pMD5 = Compute_PHash (bytes, new_seeds, hmacMD5, 16);
            }

            /* PRFを算出 */
            byte[] prf = new byte[bytes];
            for (int i = 0; i < prf.Length; i++)
                prf[i] = (byte)(pSHA1[i] ^ pMD5[i]);
            return prf;
        }

        public static string Encode(string publicKey, int choice = 2)
        {
            byte[] hashMessage = null;
            byte[] messageBytes = m_encoding.GetBytes(publicKey);

            switch (choice%6)
            {
                case 0:
                    var hmacmd5 = new HMACMD5(m_keyBytes);
                    hashMessage = hmacmd5.ComputeHash(messageBytes);
                    break;
                case 1:
                    var hmacripedmd160 = new HMACRIPEMD160(m_keyBytes);
                    hashMessage = hmacripedmd160.ComputeHash(messageBytes);
                    break;
                case 2:
                    var hmacsha1 = new HMACSHA1(m_keyBytes);
                    hashMessage = hmacsha1.ComputeHash(messageBytes);
                    break;
                case 3:
                    var hmacsha256 = new HMACSHA256(m_keyBytes);
                    hashMessage = hmacsha256.ComputeHash(messageBytes);
                    break;
                case 4:
                    var hmacsha384 = new HMACSHA384(m_keyBytes);
                    hashMessage = hmacsha384.ComputeHash(messageBytes);
                    break;
                case 5:
                    var hmacsha512 = new HMACSHA512(m_keyBytes);
                    hashMessage = hmacsha512.ComputeHash(messageBytes);
                    break;
            }

            return Convert.ToBase64String(hashMessage);
        }

 public static string Hash(string key, string message)
 {
     UTF8Encoding encoding = new UTF8Encoding();
     var messageBytes = encoding.GetBytes(message);
     var md5Hasher = new HMACMD5(encoding.GetBytes(key));
     var hashBytes = md5Hasher.ComputeHash(messageBytes);
     return new string(hashBytes.SelectMany(b => b.ToString("X2")).ToArray()).ToLower();
 }

 public byte[] HashingAMessageWithASecretKey(byte[] iterationNumberByte, byte[] userIdByte)
 {
     using (var hmac = new HMACMD5(userIdByte))
     {
         byte[] hash = hmac.ComputeHash(iterationNumberByte);
         return hash;
     }
 }

		public void CheckB (string testName, byte[] key, byte[] data, byte[] result) 
		{
			algo = new HMACMD5 ();
			algo.Key = key;
			byte[] hmac = algo.ComputeHash (data, 0, data.Length);
			AssertEquals (testName + "b1", result, hmac);
			AssertEquals (testName + "b2", result, algo.Hash);
		}

        public override void Initialize()
        {
            base.Initialize();

              if (md5 == null)
            md5 = new HMACMD5();
              else
            md5.Initialize();
        }

        /// <summary>
        /// Creates an HMAC-MD5 fingerprint of the given data with the given key using the specified encoding
        /// </summary>
        /// <param name="data"></param>
        /// <param name="key"></param>
        /// <param name="enc"></param>
        /// <returns></returns>
        public static string HMACMD5(this string data, string key, Encoding enc)
        {
            var hmacKey = enc.GetBytes(key);
            var hmacData = enc.GetBytes(data);

            using (var hmacMd5 = new HMACMD5(hmacKey)) {
                return hmacMd5.ComputeHash(hmacData).ToHex().ToLower();
            }
        }

        /**
        *
        * This is the constructor of the class
        * Three parameters are needed to build an object of this type
        *
        * @param key this represents your private. You should contact the NitroSell Support Team to request one.
        * @param userid this represents your User ID as assigned by the retailer to which you would like to query his data
        * @param webstoreUrl this is the URL of the WebStore that you would like to query
        */
        public NScAPIWrapper(string key, string userid, string webstoreUrl)
        {
            this._key = key;
            this._userid = userid;
            this._webstoreUrl = webstoreUrl;

            var keyByte = encoding.GetBytes(key);
            this._hmacmd5 = new HMACMD5(keyByte);
        }

		public void Constructors () 
		{
			algo = new HMACMD5 ();
			Assert.IsNotNull (algo, "HMACMD5 ()");

			byte[] key = new byte [8];
			algo = new HMACMD5 (key);
			Assert.IsNotNull (algo, "HMACMD5 (key)");
		}

        /// <summary>
        /// Decrypt the encoded file and compare to original file. It returns false if the file is corrupted.
        /// </summary>
        /// <param name="key">The key used to encode the file</param>
        /// <param name="sourceFile">The file to decrypt complete path</param>
        /// <param name="destFile">Destination file complete path. If the file doesn't exist, it creates it</param>
        /// <returns></returns>
        public bool DecodeFile(string key, String sourceFile, String destFile)
        {
            if (sourceFile.IsNullOrWhiteSpace() || !File.Exists(sourceFile))
                throw new FileNotFoundException("Cannot find the specified source file", sourceFile ?? "null");

            if (destFile.IsNullOrWhiteSpace())
                throw new ArgumentException("Please specify the path of the output path", nameof(destFile));

            if (string.IsNullOrEmpty(key))
                throw new ArgumentException("Please specify the key", nameof(key));

            // Create a key using a random number generator. This would be the
            //  secret key shared by sender and receiver.
            byte[] secretkey = key.ToByteArray();

            // Initialize the keyed hash object.
            HMACMD5 hmacMD5 = new HMACMD5(secretkey);
            // Create an array to hold the keyed hash value read from the file.
            byte[] storedHash = new byte[hmacMD5.HashSize / 8];
            // Create a FileStream for the source file.
            FileStream inStream = new FileStream(sourceFile, FileMode.Open);
            // Read in the storedHash.
            inStream.Read(storedHash, 0, storedHash.Length);
            // Compute the hash of the remaining contents of the file.
            // The stream is properly positioned at the beginning of the content,
            // immediately after the stored hash value.
            byte[] computedHash = hmacMD5.ComputeHash(inStream);
            // compare the computed hash with the stored value
            int i;
            for (i = 0; i < storedHash.Length; i++)
            {
                if (computedHash[i] != storedHash[i])
                {
                    inStream.Close();
                    return false;
                }
            }

            FileStream outStream = new FileStream(destFile, FileMode.Create);
            // Reset inStream to the beginning of the file.
            inStream.Position = i;
            // Copy the contents of the sourceFile to the destFile.
            int bytesRead;
            // read 1K at a time
            byte[] buffer = new byte[1024];
            do
            {
                // Read from the wrapping CryptoStream.
                bytesRead = inStream.Read(buffer, 0, 1024);
                outStream.Write(buffer, 0, bytesRead);
            } while (bytesRead > 0);
            // Close the streams
            inStream.Close();
            outStream.Close();
            return true;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="plainText"></param>
        /// <param name="key"></param>
        /// <param name="encoding"></param>
        /// <param name="encryptedType"></param>
        /// <returns></returns>
        public override string DoEncrypt(string plainText, string key, Encoding encoding, DataMode encryptedType)
        {
            byte[] keyByte = encoding.GetBytes(key);
            HMACMD5 hmacMD5 = new HMACMD5(keyByte);

            byte[] messageBytes = encoding.GetBytes(plainText);
            byte[] hashMessage = hmacMD5.ComputeHash(messageBytes);

            return BytesToString(hashMessage, encoding, encryptedType);
        }