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Diffstat (limited to 'docs/hazmat/backends')
-rw-r--r-- | docs/hazmat/backends/index.rst | 34 | ||||
-rw-r--r-- | docs/hazmat/backends/interfaces.rst | 141 | ||||
-rw-r--r-- | docs/hazmat/backends/openssl.rst | 25 |
3 files changed, 200 insertions, 0 deletions
diff --git a/docs/hazmat/backends/index.rst b/docs/hazmat/backends/index.rst new file mode 100644 index 00000000..a89cf0d5 --- /dev/null +++ b/docs/hazmat/backends/index.rst @@ -0,0 +1,34 @@ +.. hazmat:: + +Bindings +======== + +.. toctree:: + :maxdepth: 1 + + openssl + interfaces + + +Getting a Backend Provider +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. currentmodule:: cryptography.hazmat.backends + +``cryptography`` aims to support multiple backends to ensure it can provide +the widest number of supported cryptographic algorithms as well as supporting +platform specific implementations. + +You can get the default backend by calling +:func:`~default_backend`. + +The default backend will change over time as we implement new backends and +the libraries we use in those backends changes. + + +.. function:: default_backend() + + :returns: An object that provides at least + :class:`~interfaces.CipherBackend`, :class:`~interfaces.HashBackend`, and + :class:`~interfaces.HMACBackend`. + diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst new file mode 100644 index 00000000..b524943d --- /dev/null +++ b/docs/hazmat/backends/interfaces.rst @@ -0,0 +1,141 @@ +.. hazmat:: + +Backend Interfaces +================== + +.. currentmodule:: cryptography.hazmat.backends.interfaces + + +Backend implementations may provide a number of interfaces to support operations +such as :doc:`/hazmat/primitives/symmetric-encryption`, +:doc:`/hazmat/primitives/cryptographic-hashes`, and +:doc:`/hazmat/primitives/hmac`. + +A specific ``backend`` may provide one or more of these interfaces. + + +.. class:: CipherBackend + + A backend which provides methods for using ciphers for encryption + and decryption. + + .. method:: cipher_supported(cipher, mode) + + Check if a ``cipher`` and ``mode`` combination is supported by + this backend. + + :param cipher: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.CipherAlgorithm` + provider. + :param mode: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.Mode` provider. + + :returns: ``True`` if the specified ``cipher`` and ``mode`` combination + is supported by this backend, otherwise ``False`` + + .. method:: register_cipher_adapter(cipher_cls, mode_cls, adapter) + + Register an adapter which can be used to create a backend specific + object from instances of the + :class:`~cryptography.hazmat.primitives.interfaces.CipherAlgorithm` and + the :class:`~cryptography.hazmat.primitives.interfaces.Mode` primitives. + + :param cipher_cls: A class whose instances provide + :class:`~cryptography.hazmat.primitives.interfaces.CipherAlgorithm` + :param mode_cls: A class whose instances provide: + :class:`~cryptography.hazmat.primitives.interfaces.Mode` + :param adapter: A ``function`` that takes 3 arguments, ``backend`` (a + :class:`CipherBackend` provider), ``cipher`` (a + :class:`~cryptography.hazmat.primitives.interfaces.CipherAlgorithm` + provider ), and ``mode`` (a + :class:`~cryptography.hazmat.primitives.interfaces.Mode` provider). + It returns a backend specific object which may be used to construct + a :class:`~cryptogrpahy.hazmat.primitives.interfaces.CipherContext`. + + + .. method:: create_symmetric_encryption_ctx(cipher, mode) + + Create a + :class:`~cryptogrpahy.hazmat.primitives.interfaces.CipherContext` that + can be used for encrypting data with the symmetric ``cipher`` using + the given ``mode``. + + :param cipher: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.CipherAlgorithm` + provider. + :param mode: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.Mode` provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.CipherContext` + + :raises ValueError: When tag is not None in an AEAD mode + + + .. method:: create_symmetric_decryption_ctx(cipher, mode) + + Create a + :class:`~cryptogrpahy.hazmat.primitives.interfaces.CipherContext` that + can be used for decrypting data with the symmetric ``cipher`` using + the given ``mode``. + + :param cipher: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.CipherAlgorithm` + provider. + :param mode: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.Mode` provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.CipherContext` + + :raises ValueError: When tag is None in an AEAD mode + + +.. class:: HashBackend + + A backend with methods for using cryptographic hash functions. + + .. method:: hash_supported(algorithm) + + Check if the specified ``algorithm`` is supported by this backend. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :returns: ``True`` if the specified ``algorithm`` is supported by this + backend, otherwise ``False``. + + + .. method:: create_hash_ctx(algorithm) + + Create a + :class:`~cryptogrpahy.hazmat.primitives.interfaces.HashContext` that + uses the specified ``algorithm`` to calculate a message digest. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.HashContext` + + +.. class:: HMACBackend + + A backend with methods for using cryptographic hash functions as message + authentication codes. + + .. method:: create_hmac_ctx(algorithm) + + Create a + :class:`~cryptogrpahy.hazmat.primitives.interfaces.HashContext` that + uses the specified ``algorithm`` to calculate a hash-based message + authentication code. + + :param algorithm: An instance of a + :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm` + provider. + + :returns: + :class:`~cryptography.hazmat.primitives.interfaces.HashContext` diff --git a/docs/hazmat/backends/openssl.rst b/docs/hazmat/backends/openssl.rst new file mode 100644 index 00000000..12fbff04 --- /dev/null +++ b/docs/hazmat/backends/openssl.rst @@ -0,0 +1,25 @@ +.. hazmat:: + +OpenSSL +======= + +These are `CFFI`_ bindings to the `OpenSSL`_ C library. + +.. data:: cryptography.hazmat.backends.openssl.backend + + This is the exposed API for the OpenSSL bindings. It has two public + attributes: + + .. attribute:: ffi + + This is a :class:`cffi.FFI` instance. It can be used to allocate and + otherwise manipulate OpenSSL structures. + + .. attribute:: lib + + This is a ``cffi`` library. It can be used to call OpenSSL functions, + and access constants. + + +.. _`CFFI`: https://cffi.readthedocs.org/ +.. _`OpenSSL`: https://www.openssl.org/ |