title: Google Client Invalid JWT: Token must be a short-lived token
body: <p>I am using <a href="https://developers.google.com/api-client-library/php/start/get_started" rel="noreferrer">Google's php api client</a>.  I am running through the <a href="https://developers.google.com/api-client-library/php/auth/service-accounts" rel="noreferrer">quickstart guide</a> for service accounts.  I followed the steps perfectly (as far as I can tell).  I am running into the following error:</p>
  
  <pre><code>{
     "error": "invalid_grant",
     "error_description": "Invalid JWT: Token must be a short-lived token (60 minutes) and in a reasonable timeframe. Check your iat and exp values and use a clock with skew to account for clock differences between systems."
  }
  </code></pre>
  
  <p>From what I have read the most common problem with this error is if the system time is wrong.  I have triple checked that my timezone and date and time are synced with the atomic clock.  I used php set timezone function to set my timezone to match my computer, but I continue to get the error.  I am looking into the other part of the message that mentions the iat and exp settings, and haven't gotten anywhere yet.</p>
  
  <p>Does anyone have any ideas of how I can get past this?</p>