Interesting article about a crypography library for Python (from last week's LWN) 

https://cryptography.io/en/latest/ that aims to do Python cryptography the "right way". It's lower-layer "bindings" API is already being used by PyOpenSSL and comes with several built-in recipes for doing encryption "right" (e.g. authenticated  encryption).

Well worth a look if you need to do any sort of general purpose cryptography in Python.

(Also worth a look is https://pynacl.readthedocs.org/en/latest/ if you just want a library that will just "do the right thing")