using System;

using System.Security.Cryptography;

using System.Text;

using System.IO;

​

public class Program

{

    private static byte[] mabtyBufferOld;

    private static TripleDESCryptoServiceProvider mobjDESOld;

    private static byte[] mabtyBuffer;

    private static AesCryptoServiceProvider mobjDES;

    public const int KEY_SIZE = 16;

    static SHA256CryptoServiceProvider sha256CryptoServiceProvider;

    static byte[] key = new byte[KEY_SIZE];

    static byte[] iv = new byte[KEY_SIZE];

    public static void Main()

    {

        string current = "88OCejn6QH8=";

        string dec = Program.Current(current);

        Console.WriteLine("Val In Old \n" + dec);

        string s = Program.Encrypt(dec);

        Console.WriteLine("Val to replace with \n" + s);

        string d = Program.Decrypt(s);

        Console.WriteLine("Val decrpted \n" + d);

    }

​

    private static void Construct()

    {

        string strKey = "";

        sha256CryptoServiceProvider = new SHA256CryptoServiceProvider();

        strKey = string.Concat(strKey, "<well I'm hardly going to tell you my key...!>");

        var hash = sha256CryptoServiceProvider.ComputeHash(Encoding.UTF8.GetBytes(strKey));

        Buffer.BlockCopy(hash, 0, key, 0, KEY_SIZE);

        Buffer.BlockCopy(hash, KEY_SIZE, iv, 0, KEY_SIZE);

    }

​

    private static void Deconstruct()

    {

        if (mobjDES != null)

        {

            mobjDES = null;

        }

    }

​

    private static string Encrypt(string pstrText)

    {

        try

        {

            Construct();

            using (var cipher = new AesCryptoServiceProvider().CreateEncryptor(key, iv))

                using (var output = new MemoryStream())

                {

                    using (var cryptoStream = new CryptoStream(output, cipher, CryptoStreamMode.Write))

                    {

                        var inputBytes = Encoding.UTF8.GetBytes(pstrText);

                        cryptoStream.Write(inputBytes, 0, inputBytes.Length);

                    }

​

                    var bytes = output.ToArray();

                    return Convert.ToBase64String(bytes); //, 0, bytes.Length);

                }

        }

        catch (Exception ex)

        {

            throw new Exception(ex.Message);

        }

        finally

        {

            Deconstruct();

        }

    }

​

    private static string Decrypt(string pstrText)

    {

        try

        {

            Construct();

            var encryptedBytes = Convert.FromBase64String(pstrText);

            using (var cipher = new AesCryptoServiceProvider().CreateDecryptor(key, iv))

                using (var source = new MemoryStream(encryptedBytes))

                    using (var output = new MemoryStream())

                    {

                        using (var cryptoStream = new CryptoStream(source, cipher, CryptoStreamMode.Read))

                        {

                            cryptoStream.CopyTo(output);

                        }

​

                        return Encoding.UTF8.GetString(output.ToArray());

                    }

        }

        catch (Exception ex)

        {

            throw new Exception(ex.Message);

        }

        finally

        {

            Deconstruct();

        }

    }

​

    private static string Current(string pstrText)

    {

        string strKey = "";

        MD5CryptoServiceProvider hashmd5;

        byte[] abytKeyHash;

        strKey = string.Concat(strKey, "<well I'm hardly going to tell you my key...!>");

        hashmd5 = new MD5CryptoServiceProvider();

        abytKeyHash = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(strKey));

        hashmd5 = null;

        mobjDESOld = new TripleDESCryptoServiceProvider(); //implement DES3 encryption

        mobjDESOld.Key = abytKeyHash; //the key is the secret key hash.

        mobjDESOld.Mode = CipherMode.ECB; //CBC, CFB

        mabtyBufferOld = UTF8Encoding.UTF8.GetBytes(pstrText);

        string Enc = Convert.ToBase64String(mobjDESOld.CreateEncryptor().TransformFinalBlock(mabtyBufferOld, 0, mabtyBufferOld.Length));

        mabtyBufferOld = Convert.FromBase64String(pstrText);

        string Dec = UTF8Encoding.UTF8.GetString(mobjDESOld.CreateDecryptor().TransformFinalBlock(mabtyBufferOld, 0, mabtyBufferOld.Length));

        return Dec;

    }

}