C#소켓프로그래밍 (양방향 통신[Client]) + 암호화(AES256, base64)

using System;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
 
 
using System.Security.Cryptography;
using System.IO;
 
namespace AsyncTest
{
    public partial class Form1 : Form
    {
        private Socket clientSock;  /* client Socket */
        private Socket cbSock;      /* client Async Callback Socket */
        private byte[] recvBuffer;
 
        private const int MAXSIZE = 514;  /* 4096  */
        private string HOST = "xxx.xxx.xxx.xxx";
        private int PORT = 123;
        private string Enter_key;
        private string recvString;
 
        public Form1()
        {
            InitializeComponent();
            recvBuffer = new byte[MAXSIZE];
 
            this.DoInit();
        }
 
 
        //소켓 생성및 연결
        public void DoInit()
        {
            clientSock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            this.BeginConnect();
        }
 
 
        /*----------------------*
        *  Connection  *
        *----------------------*/
 
        public void BeginConnect()
        {
 
            tbDebug.Text = "서버 접속 대기 중";
            try
            {
                clientSock.BeginConnect(HOST, PORT, new AsyncCallback(ConnectCallBack), clientSock);
            }
            catch (SocketException se)
            {
                /*서버 접속 실패 */
                tbDebug.Text += "\r\n서버접속 실패하였습니다. " + se.NativeErrorCode;
                this.DoInit();
 
            }
 
        }
 
        /*----------------------*
        * ##### CallBack ##### *
        *  Connection  *
        *----------------------*/
        private void ConnectCallBack(IAsyncResult IAR)
        {
            try
            {
                // 보류중인 연결을 완성
                Socket tempSock = (Socket)IAR.AsyncState;
                IPEndPoint svrEP = (IPEndPoint)tempSock.RemoteEndPoint;
 
                tbDebug.Text += "\r\n 서버로 접속 성공 : " + svrEP.Address;
 
                tempSock.EndConnect(IAR);
                cbSock = tempSock;
                cbSock.BeginReceive(this.recvBuffer, 0, recvBuffer.Length, SocketFlags.None,
                                    new AsyncCallback(OnReceiveCallBack), cbSock);
            }
            catch (SocketException se)
            {
                if (se.SocketErrorCode == SocketError.NotConnected)
                {
                    tbDebug.Text += "\r\n서버 접속 실패 CallBack " + se.Message;
                    this.BeginConnect();
                }
            }
        }
 
        /*----------------------*
         *     Send   *
         *----------------------*/
        public void BeginSend(string message)
        {
            tbDebug.Text += "\r\n\r\n--------------  S  E  N  D  ----------------";
            tbDebug.Text += "\r\n\r\nSEND DATA : " + message;
            try
            {
                /* 연결 성공시 */
                if (clientSock.Connected)
                {
                    //키보드를 통해 입력한 데이터를 암호화 한다. 뒤의 숫자는 암호화에 쓰일 key이다.
                    string chiper = AES_encrypt(message, "01234567890123456789012345678901");
                    //데이터는 byte[]로 보내야하기 때문에 string -> byte
                    byte[] buffer = Encoding.UTF8.GetBytes(chiper);
                    //데이터 전송
                    clientSock.BeginSend(buffer, 0, buffer.Length, SocketFlags.None,
                                            new AsyncCallback(SendCallBack), chiper);
                }
            }
            catch (SocketException e)
            {
                tbDebug.Text = "\r\n\r\n전송 에러 : " + e.Message;
            }
        }
 
        /*----------------------*
        * ##### CallBack ##### *
        *     Send   *
        *----------------------*/
        private void SendCallBack(IAsyncResult IAR)
        {
            string message = (string)IAR.AsyncState;
            //데이터 전송에 있어서 공백이 '\0'로 채워질수 있기 때문에 이를 방지하기위해 trim() 함수를 사용한다.
            message = message.Trim('\0');
            tbDebug.Text += "\r\n\r\nBASE64ENCODING ( AES256 ( SEND DATA ) ) : " + message;
 
        }
 
 
 
        /*----------------------*
        *    Receive   *
        *----------------------*/
        public void Receive()
        {
 
            cbSock.BeginReceive(this.recvBuffer, 0, recvBuffer.Length,
                SocketFlags.None, new AsyncCallback(OnReceiveCallBack), cbSock);
        }
 
        /*----------------------*
        * ##### CallBack ##### *
        *    Receive   *
        *----------------------*/
        private void OnReceiveCallBack(IAsyncResult IAR)
        {
            try
            {
                Socket tempSock = (Socket)IAR.AsyncState;
                int nReadSize = tempSock.EndReceive(IAR);
                if (nReadSize != 0)
                {
 
                    tbDebug.Text += "\r\n\r\n--------------  R E C E I V E  -------------";
                    //수신받은 데이터의 나머지부분이 '\0'로 채워진다.
                    //그렇게 되면 복호화가 되지않기 때문에 trim() 함수를 사용하여 제거한다.
                    recvString = Encoding.UTF8.GetString(recvBuffer).Trim('\0');
                    Array.Clear(recvBuffer, 0, recvBuffer.Length);
 
                    tbDebug.Text += "\r\n\r\nBASE64ENCODING ( AES256 ( RECEIVE DATA ) ) : " + recvString;
 
                    //복호화
                    string chiper = AES_decrypt(recvString, "01234567890123456789012345678901");
                    this.tbDebug.Text += "\r\n\r\nRECEIVE DATA : " + chiper;
 
 
                }
                this.Receive();
            }
            catch (SocketException se)
            {
                if (se.SocketErrorCode == SocketError.ConnectionReset)
                {
                    this.BeginConnect();
                }
            }
        }
 
        //AES256 암호화
        public String AES_encrypt(String Input, String key)
        {
            RijndaelManaged aes = new RijndaelManaged();
            aes.KeySize = 256;
            aes.BlockSize = 128;
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            aes.Key = Encoding.UTF8.GetBytes(key);
            aes.IV = Encoding.UTF8.GetBytes("0123456789012345");
 
            var encrypt = aes.CreateEncryptor(aes.Key, aes.IV);
            byte[] xBuff = null;
            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, encrypt, CryptoStreamMode.Write))
                {
                    byte[] xXml = Encoding.UTF8.GetBytes(Input);
 
                    cs.Write(xXml, 0, xXml.Length);
                }
 
                xBuff = ms.ToArray();
                string recvdata = Encoding.Default.GetString(xBuff);
                tbDebug.Text += "\r\n\r\nAES256 ( SEND DATA ) : " + recvdata;
            }
 
            string Output = Convert.ToBase64String(xBuff);
            return Output;
        }
        //AES 256 복호화
        public string AES_decrypt(string Input, string key)
        {
            RijndaelManaged aes = new RijndaelManaged();
            aes.KeySize = 256;
            aes.BlockSize = 128;
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            aes.Key = Encoding.UTF8.GetBytes(key);
            aes.IV = Encoding.UTF8.GetBytes("0123456789012345");
 
            var decrypt = aes.CreateDecryptor();
            byte[] xBuff = null;
            using (var ms = new MemoryStream())
            {
 
                using (var cs = new CryptoStream(ms, decrypt, CryptoStreamMode.Write))
                {
                    byte[] xXml = Convert.FromBase64String(Input);
                    string recvdata = Encoding.Default.GetString(xXml);
                    tbDebug.Text += "\r\n\r\nAES256 ( RECEIVE DATA ) : " + recvdata;
 
 
                    cs.Write(xXml, 0, xXml.Length);
                }
 
                xBuff = ms.ToArray();
            }
 
            string Output = Encoding.UTF8.GetString(xBuff);
            return Output;
        }
 
 
 
        private void Form1_Load(object sender, EventArgs e)
        {
        }
 
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            Enter_key = textBox1.Text;
 
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            if (Enter_key != "")
            {
                this.BeginSend(Enter_key);
                textBox1.Text = "";
            }
        }
 
        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                button1_Click(sender, e);
            }
        }
    }
}

c#으로 코드가 이루어져 있으며 base64 Encoding,Decoding 과 aes256 암복호화를 통해 통신을 한다.

http://www.imcore.net/encryption-aes256-c-objectivec-ios-iphone-ipad-php-java-android-perl-javascript-python/

위에분의 블로그가 없었다면 암복호화에 엄청난 애를 먹었을 것이다.

Form안에 들어가는 내용이며 전체적인 소스코드는 올리지 않았다.

동작화면은 아래와 같다.