This page explains how authentication works in the FabEngine API and why it's secure the way it works.
Your user SID is part of the base URL for calling the FabEngine API. Your SID has the format AC0123456789 and you can find it right at the top of your dashboard. In contrast to your secret token, your SID is public information.
https://api.fabengine.com/2013-02-05/{YOUR_SID}/{FUNCTION_CALL}
You must always pass your own SID (and sign the request), even when calling public functions such as getPrice because we use it to keep track of API usage.