From 76da86a9d5f5b395a89e2768d07b19b23a96d8d8 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 4 Jan 2015 15:54:32 -0600
Subject: add DER backend interfaces

---
 docs/hazmat/backends/interfaces.rst            | 24 ++++++++++++++++++++++++
 src/cryptography/hazmat/backends/interfaces.py | 16 ++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index e9ee9467..3d222684 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -468,6 +468,30 @@ A specific ``backend`` may provide one or more of these interfaces.
             serialized data contains.
         :raises ValueError: If the data could not be deserialized.
 
+.. class:: DERSerializationBackend
+
+    .. versionadded:: 0.8
+
+    A backend with methods for working with DER encoded keys.
+
+    .. method:: load_der_private_key(data, password)
+
+        :param bytes data: DER data to load.
+        :param bytes password: The password to use if the data is encrypted.
+            Should be ``None`` if the data is not encrypted.
+        :return: A new instance of the appropriate type of private key that the
+            serialized data contains.
+        :raises ValueError: If the data could not be deserialized.
+        :raises cryptography.exceptions.UnsupportedAlgorithm: If the data is
+            encrypted with an unsupported algorithm.
+
+    .. method:: load_der_public_key(data)
+
+        :param bytes data: DER data to load.
+        :return: A new instance of the appropriate type of public key
+            serialized data contains.
+        :raises ValueError: If the data could not be deserialized.
+
 .. class:: X509Backend
 
     .. versionadded:: 0.7
diff --git a/src/cryptography/hazmat/backends/interfaces.py b/src/cryptography/hazmat/backends/interfaces.py
index 4dc879ac..6feb8106 100644
--- a/src/cryptography/hazmat/backends/interfaces.py
+++ b/src/cryptography/hazmat/backends/interfaces.py
@@ -232,6 +232,22 @@ class PEMSerializationBackend(object):
         """
 
 
+@six.add_metaclass(abc.ABCMeta)
+class DERSerializationBackend(object):
+    @abc.abstractmethod
+    def load_der_private_key(self, data, password):
+        """
+        Loads a priate key from DER encoded data. Uses the provided password
+        if the data is encrypted.
+        """
+
+    @abc.abstractmethod
+    def load_der_public_key(self, data):
+        """
+        Loads a public key from DER encoded data.
+        """
+
+
 @six.add_metaclass(abc.ABCMeta)
 class X509Backend(object):
     @abc.abstractmethod
-- 
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