To access and sync my Owncloud's calendar and contacts with my Android
phone in a (more-or-less) secure manner through HTTPS, I needed to get a
SSL/TLS certificate. Or precisely: a self-signed root CA (Certification
Authority) certificate.

After searching for Howtos and creating a bunch of CA certificates,
normal certificates, signing them, signing them vice-versa etc. -- yes,
I don't really have a clue -- I mostly run into one of these errors:

• when signing normal cert with CA cert: "not self-signed"
• when self-signing normal cert with itself: "no Basic Constraint CA flag"

Then I finally found (https://langui.sh/2009/01/18/openssl-self-signed-ca/)
this one-liner that does the job just fine::

$ openssl req -newkey rsa:2048 -days 365 -x509 -nodes -out root.cer

Make sure to use the domain name you want to use this certificate on as
the Common Name (CN).

This creates a certificate file (named as defined in the -out parameter)
and a key file, named 'privkey.pem' in my case. I had to upload this to
in the admin interface of my shared hoster, and 5 minutes later the
certificate was installed and accepted by DAVDroid, the Android syncing
app.

Pyfilesystem is a Python module that provides a simplified common interface to many types of filesystem. Filesystems exposed via Pyfilesystem can also be served over the network, or 'mounted' on the native filesystem.

Pyfilesystem simplifies working directories and paths, even if you only intend to work with local files. Differences in path formats between platforms are abstracted away, and you can write code that sand-boxes any changes to a given directory.

Pyfilesystem works with Linux, Windows and Mac.