การเข้ารหัส string แบบ Symmetric (SymmetricAlgorithm) ด้วย TripleDESCryptoServiceProvider

RijndaelManaged, DESCryptoServiceProvider, RC2CryptoServiceProvider, and TripleDESCryptoServiceProvider are implementations of symmetric algorithms.

• System.Security.Cryptography Namespace
• SymmetricAlgorithm Class
• TripleDESCryptoServiceProvider Class

Crypto.cs

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace ConsoleApp
{
    public class Crypto
    {
        SymmetricAlgorithm mCSP;

        #region "Constants"
        private object _key = "01234562d3dg";
        string iv = "abcdeUCVF7s=";
        #endregion

        public Crypto()
        {
        }

        public bool HasKey()
        {
            return (!(_key == null || _key.ToString() == ""));
        }

        private string SetLengthString(string str, int length)
        {
            while (length > str.Length)
            {
                str += str;
            }
            if (str.Length > length)
            {
                str = str.Remove(length);
            }
            return str;
        }

        public string EncryptString(string Value)
        {
            mCSP = SetEnc();
            mCSP.IV = Convert.FromBase64String(iv);
            string key = SetLengthString(_key.ToString(), 32);
            mCSP.Key = Convert.FromBase64String(key);
            ICryptoTransform ct;
            MemoryStream ms;
            CryptoStream cs;
            Byte[] byt = new byte[64];

            try
            {
                ct = mCSP.CreateEncryptor(mCSP.Key, mCSP.IV);

                byt = Encoding.UTF8.GetBytes(Value);

                ms = new MemoryStream();
                cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);
                cs.Write(byt, 0, byt.Length);
                cs.FlushFinalBlock();

                cs.Close();

                return Convert.ToBase64String(ms.ToArray()).Replace('/', '_').Replace('+', '-');
            }
            catch (Exception Ex)
            {
                throw (new Exception("An error occurred while encrypting string"));
            }
        }

        public string DecryptString(string Value)
        {
            mCSP = SetEnc();
            mCSP.IV = Convert.FromBase64String(iv);
            string key = SetLengthString(_key.ToString(), 32);
            mCSP.Key = Convert.FromBase64String(key);
            ICryptoTransform ct;
            MemoryStream ms;
            CryptoStream cs;
            Byte[] byt = new byte[64];
            try
            {
                ct = mCSP.CreateDecryptor(mCSP.Key, mCSP.IV);

                byt = Convert.FromBase64String(Value.Replace('_', '/').Replace('-', '+'));

                ms = new MemoryStream();
                cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);
                cs.Write(byt, 0, byt.Length);
                cs.FlushFinalBlock();

                cs.Close();

                //string str =
                return Encoding.UTF8.GetString(ms.ToArray());
            }
            catch (Exception ex)
            {
                throw (new Exception("An error occurred while decrypting string : " + ex.Message));
            }
        }

        private SymmetricAlgorithm SetEnc()
        {
            return new TripleDESCryptoServiceProvider();
        }
    }
}

Program.cs

using System;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string plainText = "Helo World!";

            Crypto crypto = new Crypto();
            string encrpytText = crypto.EncryptString(plainText);
            string decryptText= crypto.DecryptString(encrpytText);

            Console.WriteLine(string.Format("plainText   = {0}", plainText));
            Console.WriteLine(string.Format("encrpytText = {0}", encrpytText));
            Console.WriteLine(string.Format("decryptText = {0}", decryptText));
        }
    }
}

ผลการรัน

plainText   = Helo World!
encrpytText = 27KmYMudRbIROkwfhlsPpA==
decryptText = Helo World!