using System;

using System.Security.Cryptography;

using System.Text;

using System.IO;

​

public class Program

{

    public static void Main()

    {

        byte[] key = Convert.FromBase64String("mI5cojV7vCWW4Y63BhV9hA==");

           string dateString = DateTime.Now.ToString("MM/dd/yyyy HH-mm-ss");

           byte[] bytes = Encoding.UTF8.GetBytes("ffffffff-c3a6-1e23-218b-c8c60033c587-DUBAIHEALTH:" + dateString);

           byte[] bytesUpdated;

​

           if (bytes == null || bytes.Length == 0 || key == null || key.Length == 0)

               throw new ArgumentNullException();

​

           byte[] iv = new byte[] { 0x40, 0x24, 0x26, 0x7, 0x7A, 0x23, 0x2B, 0x2F, 0x69, 0x7D, 0x73, 0x28, 0x5C, 0x48, 0x19, 0x25 };

​

           using (var memoryStream = new MemoryStream())

           {

               using (var rijndaelManaged = new RijndaelManaged { Key = key, IV = iv, Padding = PaddingMode.PKCS7, Mode = CipherMode.CBC })

               {

                   using (var cryptoStream = new CryptoStream(memoryStream, rijndaelManaged.CreateEncryptor(key, iv), CryptoStreamMode.Write))

                   {

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

                   }

               }

               bytesUpdated = memoryStream.ToArray();

           }

           string converted;

           converted = Convert.ToBase64String(bytesUpdated);

        Console.WriteLine(converted);

    }

}