using System;

using System.Text;

using System.Collections.Generic;

enum ProtocolType  {TCP , UDP};

​

public class Program

{

internal static byte[] EncryptMessage(byte[] pMessage, ProtocolType pProtocolType)

{

    List<byte> mBuffer = new List<byte>();

    int key = 0xAB;

​

    if ((pMessage != null) && (pMessage.Length > 0))

    {

        //Add Header if TCP

        if (pProtocolType == ProtocolType.TCP)

        {

            byte[] intBytes = BitConverter.GetBytes(pMessage.Length);

            if (BitConverter.IsLittleEndian) Array.Reverse(intBytes);

            mBuffer.AddRange(intBytes);

        }

​

        for (int i = 0; i < pMessage.Length; i++)

        {

            byte b = (byte)(key ^ pMessage[i]);

            key = b;

            mBuffer.Add(b);

        }

    }

    return mBuffer.ToArray();

}

internal static byte[] DecryptMessage(byte[] pMessage, ProtocolType pProtocolType)

{

    List<byte> mBuffer = new List<byte>();

    int key = 0xAB;

​

    //Skip the first 4 bytes in TCP communications (4 bytes header)

    int header = 0;

        if (pProtocolType == ProtocolType.TCP)

        {

            header = 4;

            byte[] intBytes = new byte[4];

            Array.Copy(pMessage,0,intBytes,0,4);

            if (BitConverter.IsLittleEndian) Array.Reverse(intBytes);

            Console.WriteLine(BitConverter.ToInt32(intBytes,0));

        }

    if ((pMessage != null) && (pMessage.Length > 0))

    {

        for (int i = header; i < pMessage.Length; i++)

        {

            byte b = (byte)(key ^ pMessage[i]);

            key = pMessage[i];

            mBuffer.Add(b);

        }

    }

​

    return mBuffer.ToArray();

}   

​

public static void Main(){

    string input;

    byte[] inputBytes;

        input = "{\"system\":{\"get_sysinfo\":{}}}";

        //input = "abc";

        Console.WriteLine("String:");

        Console.WriteLine(input);

        inputBytes = Encoding.UTF8.GetBytes(input);

​

        byte[] encryptedBytes = EncryptMessage(inputBytes, ProtocolType.TCP);

        StringBuilder sb = new StringBuilder(encryptedBytes.Length * 2);

        foreach (byte b in encryptedBytes)

        {

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

        }

        Console.WriteLine(sb);

        string encryptedStr = Encoding.UTF8.GetString(encryptedBytes);

        Console.WriteLine("Encrypted string:");

        Console.WriteLine(encryptedStr);

        byte[] decryptedBytes = DecryptMessage(encryptedBytes, ProtocolType.TCP);

        string decryptedStr = Encoding.UTF8.GetString(decryptedBytes);

​

        Console.WriteLine("Decrypted string:");

        Console.WriteLine(decryptedStr);

​

}   

}