Scrypt Implementation (#3117)
* Scrypt implementation.
* Docs stuff.
* Make example just an example and not a doctest.
* Add changelog entry.
* Docs cleanup.
* Add more tests.
* Add multibackend tests.
* PEP8.
* Add docs about Scrypt parameters.
* Docs cleanup.
* Add AlreadyFinalized.
diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index 14f72cf..b79bb23 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -652,3 +652,33 @@
:returns: ``True`` if the given values of ``p`` and ``g`` are supported
by this backend, otherwise ``False``.
+
+
+.. class:: ScryptBackend
+
+ .. versionadded:: 1.6
+
+ A backend with methods for using Scrypt.
+
+ The following backends implement this interface:
+
+ * :doc:`/hazmat/backends/openssl`
+
+ .. method:: derive_scrypt(self, key_material, salt, length, n, r, p)
+
+ :param bytes key_material: The key material to use as a basis for
+ the derived key. This is typically a password.
+
+ :param bytes salt: A salt.
+
+ :param int length: The desired length of the derived key.
+
+ :param int n: CPU/Memory cost parameter. It must be larger than 1 and be a
+ power of 2.
+
+ :param int r: Block size parameter.
+
+ :param int p: Parallelization parameter.
+
+ :return bytes: Derived key.
+
diff --git a/docs/hazmat/backends/openssl.rst b/docs/hazmat/backends/openssl.rst
index 8bc7dac..791aab3 100644
--- a/docs/hazmat/backends/openssl.rst
+++ b/docs/hazmat/backends/openssl.rst
@@ -24,6 +24,11 @@
* :class:`~cryptography.hazmat.backends.interfaces.PEMSerializationBackend`
* :class:`~cryptography.hazmat.backends.interfaces.X509Backend`
+ It also implements the following interface for OpenSSL versions ``1.1.0``
+ and above.
+
+ * :class:`~cryptography.hazmat.backends.interfaces.ScryptBackend`
+
It also exposes the following:
.. attribute:: name