.. _ssl-tutorial:

==============================
SSL and certificate validation
==============================

All SSL configuration is done per-storage.

Pinning by fingerprint
----------------------

To pin the certificate by SHA1- or MD5-fingerprint::

    [storage foo]
    type = caldav
    ...
    verify_fingerprint = "94:FD:7A:CB:50:75:A4:69:82:0A:F8:23:DF:07:FC:69:3E:CD:90:CA"
    #verify = false  # Optional: Disable CA validation, useful for self-signed certs

You can use the following command for obtaining a SHA-1 fingerprint::

    echo -n | openssl s_client -connect unterwaditzer.net:443 | openssl x509 -noout -fingerprint

.. _ssl-cas:

Custom root CAs
---------------

To point vdirsyncer to a custom set of root CAs::

    [storage foo]
    type = caldav
    ...
    verify = "/path/to/cert.pem"

Vdirsyncer uses the requests_ library, which, by default, `uses its own set of
trusted CAs
<http://www.python-requests.org/en/latest/user/advanced/#ca-certificates>`_.

However, the actual behavior depends on how you have installed it. Some Linux
distributions, such as Debian, patch their ``python-requests`` package to use
the system certificate CAs. Normally these two stores are similar enough for
you to not care.

But there are cases where certificate validation fails even though you can
access the server fine through e.g. your browser. This usually indicates that
your installation of the ``requests`` library is somehow broken. In such cases,
it makes sense to explicitly set ``verify`` or ``verify_fingerprint`` as shown
above.

.. _requests: http://www.python-requests.org/

.. _ssl-client-certs:

Client Certificates
-------------------

Client certificates may be specified with the ``auth_cert`` parameter. If the
key and certificate are stored in the same file, it may be a string::

   [storage foo]
   type = caldav
   ...
   auth_cert = "/path/to/certificate.pem"

If the key and certificate are separate, a list may be used::

   [storage foo]
   type = caldav
   ...
   auth_cert = ["/path/to/certificate.crt", "/path/to/key.key"]