Issue with urllib3[secure]

[Kemal Ficici]

I'm trying to run a sample program from assistant-sdk-python, and I keep getting this error

Traceback (most recent call last):
  File "/usr/bin/googlesamples-assistant-hotword", line 11, in <module>
    load_entry_point('google-assistant-sdk==0.3.3', 'console_scripts', 
'googlesamples-assistant-hotword')()
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 
570, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 
2687, in load_entry_point
    return ep.load()
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 
2340, in load
    self.require(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 
2363, in require
    items = working_set.resolve(reqs, env, installer, extras=self.extras)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 
867, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'cryptography>=1.3.4; python_version 
<= "2.7" and extra == "secure"' distribution was not found and is required 
by urllib3

I have urllib3[secure] installed, with cryptography 2.0.3, so I shouldn't be having any issues. I've tried looking for others with this error, and I can't seem to find a solution. How can I fix this?