public ActionResult Details(int?id)
        {
            if (id == null)
            {
                return(new HttpStatusCodeResult(HttpStatusCode.BadRequest));
            }
            ProvaModel prov = db.Textos.Find(id);

            if (prov == null)
            {
                return(HttpNotFound());
            }

            AesCryptoServiceProvider aes = new AesCryptoServiceProvider();

            aes.BlockSize = 128;
            aes.KeySize   = 256;
            aes.IV        = Encoding.UTF8.GetBytes(AesIV256BD);
            aes.Key       = Encoding.UTF8.GetBytes(AesKey256BD);
            aes.Mode      = CipherMode.CBC;
            aes.Padding   = PaddingMode.PKCS7;
            string msgE = prov.Texto;

            byte[] src = Convert.FromBase64String(prov.Texto);
            using (ICryptoTransform decrypt = aes.CreateDecryptor())
            {
                byte[] dest = decrypt.TransformFinalBlock(src, 0, src.Length);
                prov.Texto = Encoding.Unicode.GetString(dest);
            }
            string msgD = prov.Texto;

            TempData["msgE"] = msgE;
            TempData["msgD"] = msgD;

            return(View());
        }