49 lines
1.6 KiB
ReStructuredText
49 lines
1.6 KiB
ReStructuredText
.. hazmat::
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OpenSSL binding
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===============
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.. currentmodule:: cryptography.hazmat.bindings.openssl.binding
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These are `CFFI`_ bindings to the `OpenSSL`_ C library. Cryptography supports
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OpenSSL version ``1.0.0`` and greater.
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.. class:: cryptography.hazmat.bindings.openssl.binding.Binding()
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This is the exposed API for the OpenSSL bindings. It has two public
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attributes:
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.. attribute:: ffi
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This is a ``cffi.FFI`` instance. It can be used to allocate and
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otherwise manipulate OpenSSL structures.
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.. attribute:: lib
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This is a ``cffi`` library. It can be used to call OpenSSL functions,
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and access constants.
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.. classmethod:: init_static_locks
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Enables the best available locking callback for OpenSSL.
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See :ref:`openssl-threading`.
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.. _openssl-threading:
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Threading
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---------
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``cryptography`` enables OpenSSLs `thread safety facilities`_ in two different
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ways depending on the configuration of your system. Normally the locking
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callbacks provided by your Python implementation specifically for OpenSSL will
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be used. However, if you have linked ``cryptography`` to a different version of
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OpenSSL than that used by your Python implementation we enable an alternative
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locking callback. This version is implemented in Python and so may result in
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lower performance in some situations. In particular parallelism is reduced
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because it has to acquire the GIL whenever any lock operations occur within
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OpenSSL.
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.. _`CFFI`: https://cffi.readthedocs.io
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.. _`OpenSSL`: https://www.openssl.org/
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.. _`thread safety facilities`: https://www.openssl.org/docs/man1.0.2/crypto/threads.html
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