Python wrapper around a small subset of the OpenSSL library.  Includes:

- SSL.Connection objects, wrapping the methods of Python's portable sockets
- Callbacks written in Python
- Extensive error-handling mechanism, mirroring OpenSSL's error codes

and much more.

Note: The Python Cryptographic Authority strongly suggests the use of
pyca/cryptography where possible. If you are using pyOpenSSL for anything
other than making a TLS connection you should move to cryptography and
drop your pyOpenSSL dependency.