documentation improvements for KDF
diff --git a/docs/hazmat/primitives/index.rst b/docs/hazmat/primitives/index.rst
index 2a29bd8..bde0739 100644
--- a/docs/hazmat/primitives/index.rst
+++ b/docs/hazmat/primitives/index.rst
@@ -9,7 +9,7 @@
cryptographic-hashes
hmac
symmetric-encryption
- key-derivation-functions
padding
+ key-derivation-functions
constant-time
interfaces
diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst
index af2d910..51d73bc 100644
--- a/docs/hazmat/primitives/key-derivation-functions.rst
+++ b/docs/hazmat/primitives/key-derivation-functions.rst
@@ -10,8 +10,16 @@
.. class:: PBKDF2(algorithm, length, salt, iterations, backend):
+ .. versionadded:: 0.2
+
+ This class conforms to the
+ :class:`~cryptography.hazmat.primitives.interfaces.KeyDerivationFunction`
+ interface.
+
.. doctest::
+ >>> import os
+ >>> from cryptography.hazmat.primitives import hashes
>>> from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2
>>> from cryptography.hazmat.backends import default_backend
>>> backend = default_backend()
@@ -22,19 +30,18 @@
>>> # verify
>>> kdf = PBKDF2(hashes.SHA1(), 20, salt, 10000, backend)
>>> kdf.verify(b"my great password", key)
- None
- :param algorithm: An instance of a
- :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
- provider.
-
- :param int length: The desired length of the derived key. Maximum is
+ :param algorithm: An instance of a
+ :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
+ provider.
+ :param int length: The desired length of the derived key. Maximum is
2\ :sup:`31` - 1.
-
- :param bytes salt: A salt. `NIST SP 800-132`_ recommends 128-bits or
- longer.
-
- :param int iterations: The number of iterations to perform of the hash
- function.
+ :param bytes salt: A salt. `NIST SP 800-132`_ recommends 128-bits or
+ longer.
+ :param int iterations: The number of iterations to perform of the hash
+ function.
+ :param backend: A
+ :class:`~cryptography.hazmat.backends.interfaces.CipherBackend`
+ provider.
.. _`NIST SP 800-132`: http://csrc.nist.gov/publications/nistpubs/800-132/nist-sp800-132.pdf