fix erroneous indent and add abstractmethod to HMACBackend
diff --git a/cryptography/hazmat/backends/interfaces.py b/cryptography/hazmat/backends/interfaces.py
index 912476b..9a57096 100644
--- a/cryptography/hazmat/backends/interfaces.py
+++ b/cryptography/hazmat/backends/interfaces.py
@@ -60,6 +60,13 @@
class HMACBackend(six.with_metaclass(abc.ABCMeta)):
@abc.abstractmethod
+ def hmac_supported(self, algorithm):
+ """
+ Return True if the hash algorithm is supported for HMAC by this
+ backend.
+ """
+
+ @abc.abstractmethod
def create_hmac_ctx(self, key, algorithm):
"""
Create a HashContext for calculating a message authentication code.
diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index 45fbaf0..5b6cd64 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -141,8 +141,8 @@
Create a
:class:`~cryptogrpahy.hazmat.primitives.interfaces.HashContext` that
- uses the specified ``algorithm`` to calculate a hash-based message
- authentication code.
+ uses the specified ``algorithm`` to calculate a hash-based message
+ authentication code.
:param algorithm: An instance of a
:class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`