title: How to create MD5 hash with HMAC module in Ruby?
body: <p>Using Google + Bing didn't yield an answer to what should be a simple question:</p>
  
  <p>How are you supposed to use the HMAC module in Ruby to create a HMAC with MD5 (that uses a secret)?</p>
  
  <p>The HMAC docs seem awfully thin.</p>
  
  <p>Thanks!</p>