title: Something like Tryparse from Convert.FromBase64String
body: <p>Is there any tryparse for <code>Convert.FromBase64String</code>
  or we just count the character if it is equal 64 character or not.</p>
  
  <p>I copy a encryption and decryption class, but there is an error on the following line.  I want to check whether or not the <code>cipherText</code> can be converted without error</p>
  
  <pre><code>byte[] bytes = Convert.FromBase64String(cipherText);
  </code></pre>