The API password and hash authentication options will be officially deprecated effective May 31, 2016. API calls using either method will no longer function.
What does this mean or look like? I just started to experience a return from the api when fetching a contact list of code 400 but the auth part must of worked. Yet I wanted to verify since the status page says everything is operational.
The password and hash authentication options have been retired at this point and the API key authentication described here should be used going forward:
I hope this helps clarify