Supporting Python 3.8 not only required configuring Tox and Travis to
run the tests on that version, but also required updating the
dependencies. Without that update, `pluggy` wouldn't work properly.

Reject cyphertexts that have been modified by prepending zero bytes, by
checking the cyphertext length against the expected size (given the
decryption key). This resolves CVE-2020-13757.

The same approach is used when verifying a signature.

Thanks Carnil for pointing this out on https://github.com/sybrenstuvel/python-rsa/issues/146

This is a requirement for RSA blinding, but wasn't implemented yet.

I've overridden the default configuration in such a way that the code as
it is now passes all the code smells checks. Especially the default code
complexity threshold is extremely low.