title: Golang generating a 32 byte key
body: <p>I am using this library for sessions.</p>
  
  <p><a href="https://github.com/codegangsta/martini-contrib/tree/master/sessions" rel="noreferrer">https://github.com/codegangsta/martini-contrib/tree/master/sessions</a></p>
  
  <p>It says that:</p>
  
  <p><em>It is recommended to use an authentication key with 32 or 64 bytes. The encryption key, if set, must be either 16, 24, or 32 bytes to select AES-128, AES-192, or AES-256 modes.</em></p>
  
  <p>How do I generate a 64 byte key, is it as straightforward as <code>[]byte"64characterslongstring"</code>, I thought it is not always so straight forward?</p>