using System;

using System.IO;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        var stringToDecrypt = "lK+M8En37/KsbB1coNCspw==";

        var IV = "2y9yV2639n6k7f5X";

        var Key = "A16cHnygxCRxumMiKanlaC0OVgaOFIp0";

        byte[] vectorBytes = ASCIIEncoding.ASCII.GetBytes(IV);

            byte[] output = null;

            using (AesManaged cipher = new AesManaged())

            {

                byte[] keyBytes = ASCIIEncoding.ASCII.GetBytes(Key);

                cipher.Mode = CipherMode.CBC;

                using (MemoryStream fsCrypt = new MemoryStream(Convert.FromBase64String(stringToDecrypt)))

                {

                    using (MemoryStream fsOut = new MemoryStream())

                    {

                        using (ICryptoTransform decryptor = cipher.CreateDecryptor(keyBytes, vectorBytes))

                        {

                            using (CryptoStream cs = new CryptoStream(fsCrypt, decryptor, CryptoStreamMode.Read))

                            {

                                int data;

                                while ((data = cs.ReadByte()) != -1)

                                {

                                    fsOut.WriteByte((byte)data);

                                }

                            }

                        }

                        output = fsOut.ToArray();

                    }

                }

                cipher.Clear();

            }

        Console.WriteLine(Encoding.UTF8.GetString(output));

    }

}