title: How to send MD5 hash of empty byte array?
body: <p>I need to send a request from PHP to a C# WEB API.
  As part of the authentication it requires an MD5 hash of an empty byte array.</p>
  
  <p><strong>How can I generate an MD5 hash of an empty byte array on PHP?</strong>
  I would do it like this in C#.</p>
  
  <pre><code>byte[] Content = new byte[0];
  using (var md5 = MD5.Create())
  {
    return md5.ComputeHash(content);
  }
  </code></pre>