using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            byte[] bytes = Encoding.UTF8.GetBytes("Kanxue2019CTF-Q1");
            byte[] bytes3 = new PasswordDeriveBytes("Kanxue2019", null).GetBytes(32);

            //string key_base64 = "4RTlF9Ca2+oqExJwx68FiA==";
            //StringBuilder key = new StringBuilder();
            //foreach (byte b in Convert.FromBase64String(key_base64).ToArray())
            //{
            //    //Format as hex 
            //    key.AppendFormat("{0:X2}", b);
            //}
            //Console.WriteLine("{0}", key.ToString());

            string ret1 = "E114E517D09ADBEA2A131270C7AF0588";

            ICryptoTransform transform = new RijndaelManaged
            {
                Mode = CipherMode.CBC
            }.CreateDecryptor(bytes3, bytes);

            byte[] inputByteArray = new byte[ret1.Length / 2];

            for (int x = 0; x < ret1.Length / 2; x++)
            {
                int i = (Convert.ToInt32(ret1.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            MemoryStream memoryStream = new MemoryStream();
            CryptoStream cryptoStream = new CryptoStream(memoryStream, transform, CryptoStreamMode.Write);
            cryptoStream.Write(inputByteArray, 0, inputByteArray.Length);
            cryptoStream.FlushFinalBlock();

            byte[] inArray = memoryStream.ToArray();
            memoryStream.Close();
            cryptoStream.Close();

            string returnStr = "";
            for (int i = 0; i < inArray.Length; i++)
            {
                returnStr += inArray[i].ToString("X2");
            }
            Console.WriteLine("{0}", returnStr);
        }
    }
}