title: HMAC md5 encryption/decryption in PHP
body: <p>I have the php code for making HMAC md5 encryption</p>
  
  <pre><code>$input = 'foo';
  $output = hash_hmac('md5', $input, $secretKey);
  </code></pre>
  
  <p>After making the hash,is there anyway I could get the $input back to text form.</p>