title: How to hash a string with a secret key and MD5 algorithm in C#?
body: <p>I am working on an API which requires a header for API authentication. The header contains a hash string which is created using md5 algorithm and a secret key. I want to write a function like this:</p>
  <pre><code>public string CreateMD5Hash(string input, string secretKey)
  {
      return output;
  }
  </code></pre>
  <p>I tried to use bouncy castle API. But I couldn't find proper documentation. That is why I couldn't make it use.</p>