using System;

using System.IO;

using System.Security.Cryptography;

using System.Text;

public class Program

{

    private const string IV = "dfdae1826068b42d";

    private const string EXTRA_KEY = "nanrenyaoxuexidadanvrenyaoxuepengmama";

    public static void Main()

    {

        Console.WriteLine(Decrypt());

    }

    public static string Decrypt(){

            string key = "dfdae1826068b42d";

            string encrypt = "2VXgoTwxsxkUDEr62gGyPwMZAvL q Uf6DZ7vziiUGAFxSTRRwDbCiXog1 KPbwtelzmgO6WOyBJiAOWlQerOE1yYjfGXEyakBWd3XvvRPtzdm63e8T4z252Jd59HG19Ow37cw0LPmsxM WsmrwIx2wcbQ5Oeldsi DKe/k72ZsN7XDuEUUJstwpwCQ9mD Nmup4m2MCa4W/CPbu2bK4brSwAE7j2wZ84O14ic6ThF wW2DbPg4YqQXZjl/dy3tkLYqfAETgdHAzkNsacljg4A==";

            if (key.Length < 32)

            {

                key += EXTRA_KEY.Substring(0, 32 - key.Length);

            }else if (key.Length > 32)

            {

                key = key.Substring(0, 32);

            }

            RijndaelManaged rijndaelManaged = GetRijndaelManaged(key);

            byte[] buffer = Convert.FromBase64String(encrypt.Replace(" ", "+"));

​

            using (var memoryStream = new MemoryStream())

            {

                using (var cryptoStream = new CryptoStream((Stream)memoryStream, rijndaelManaged.CreateDecryptor(), CryptoStreamMode.Write))

                {

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

                    cryptoStream.FlushFinalBlock();

​

                    return Encoding.UTF8.GetString(memoryStream.ToArray()).Trim();

                }

            }

    }

    private static RijndaelManaged GetRijndaelManaged(string key)

        {

            return new RijndaelManaged

            {

                KeySize = key.Length * 8,

                BlockSize = 128,

                Key = Encoding.UTF8.GetBytes(key),

                IV = Encoding.UTF8.GetBytes(IV)

            };

        }

}