The cryptography library is designed to be a "one-stop-shop" for
 all your cryptographic needs in Python.
 .
 As an alternative to the libraries that came before it, cryptography
 tries to address some of the issues with those libraries:
  - Lack of PyPy and Python 3 support.
  - Lack of maintenance.
  - Use of poor implementations of algorithms (i.e. ones with known
    side-channel attacks).
  - Lack of high level, "Cryptography for humans", APIs.
  - Absence of algorithms such as AES-GCM.
  - Poor introspectability, and thus poor testability.
  - Extremely error prone APIs, and bad defaults.