- update to 3.1:
* **BACKWARDS INCOMPATIBLE:** Removed support for ``idna`` based
:term:`U-label` parsing in various X.509 classes. This support was originally
deprecated in version 2.1 and moved to an extra in 2.5.
* Deprecated OpenSSL 1.0.2 support. OpenSSL 1.0.2 is no longer supported by
the OpenSSL project. The next version of ``cryptography`` will drop support
for it.
* Deprecated support for Python 3.5. This version sees very little use and will
be removed in the next release.
* ``backend`` arguments to functions are no longer required and the
default backend will automatically be selected if no ``backend`` is provided.
* Added initial support for parsing certificates from PKCS7 files with
:func:`~cryptography.hazmat.primitives.serialization.pkcs7.load_pem_pkcs7_certificates`
and
:func:`~cryptography.hazmat.primitives.serialization.pkcs7.load_der_pkcs7_certificates`
.
* Calling ``update`` or ``update_into`` on
:class:`~cryptography.hazmat.primitives.ciphers.CipherContext` with ``data``
longer than 2\ :sup:`31` bytes no longer raises an ``OverflowError``. This
also resolves the same issue in :doc:`/fernet`.