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

public class Program
{
	public static void Main()
	{
		DecryptString("BQO5l5Kj9MdErXx6Q6AGOw==", "c4scadek3y654321");
	}

	public static string EncryptString(string Plaintext, string Key)
        {
            byte[] bytes = Encoding.UTF8.GetBytes(Plaintext);
            Aes aes = Aes.Create();
            aes.BlockSize = 128;
            aes.KeySize = 128;
            aes.IV = Encoding.UTF8.GetBytes("1tdyjCbY1Ix49842");
            aes.Key = Encoding.UTF8.GetBytes(Key);
            aes.Mode = CipherMode.CBC;
            string result;
            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (CryptoStream cryptoStream = new CryptoStream(memoryStream, aes.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cryptoStream.Write(bytes, 0, bytes.Length);
                    cryptoStream.FlushFinalBlock();
                }
                result = Convert.ToBase64String(memoryStream.ToArray());
            }
            return result;
        }

	public static string DecryptString(string EncryptedString, string Key)
        {
            byte[] array = Convert.FromBase64String(EncryptedString);
            Aes aes = Aes.Create();
            aes.KeySize = 128;
            aes.BlockSize = 128;
            aes.IV = Encoding.UTF8.GetBytes("1tdyjCbY1Ix49842");
            aes.Mode = CipherMode.CBC;
            aes.Key = Encoding.UTF8.GetBytes(Key);
            string @string;
            using (MemoryStream memoryStream = new MemoryStream(array))
            {
                using (CryptoStream cryptoStream = new CryptoStream(memoryStream, aes.CreateDecryptor(), CryptoStreamMode.Read))
                {
                    byte[] array2 = new byte[checked(array.Length - 1 + 1)];
                    cryptoStream.Read(array2, 0, array2.Length);
                    @string = Encoding.UTF8.GetString(array2);
                }
            }
		Console.WriteLine(@string);
            return @string;
        }


}