Multibackend now supports all of RSABackend

Also convert some examples to doctest

3 files changed, 102 insertions, 34 deletions

diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py
index 753f4fc6..c5c652db 100644
--- a/cryptography/hazmat/backends/multibackend.py
+++ b/cryptography/hazmat/backends/multibackend.py
@@ -146,6 +146,24 @@ class MultiBackend(object):
         raise UnsupportedAlgorithm("RSA is not supported by the backend",
                                    _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
 
+    def mgf1_hash_supported(self, algorithm):
+        for b in self._filtered_backends(RSABackend):
+            return b.mgf1_hash_supported(algorithm)
+        raise UnsupportedAlgorithm("RSA is not supported by the backend",
+                                   _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
+
+    def decrypt_rsa(self, private_key, ciphertext, padding):
+        for b in self._filtered_backends(RSABackend):
+            return b.decrypt_rsa(private_key, ciphertext, padding)
+        raise UnsupportedAlgorithm("RSA is not supported by the backend",
+                                   _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
+
+    def encrypt_rsa(self, public_key, plaintext, padding):
+        for b in self._filtered_backends(RSABackend):
+            return b.encrypt_rsa(public_key, plaintext, padding)
+        raise UnsupportedAlgorithm("RSA is not supported by the backend",
+                                   _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
+
     def generate_dsa_parameters(self, key_size):
         for b in self._filtered_backends(DSABackend):
             return b.generate_dsa_parameters(key_size)
diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst
index 2700154c..7bae7142 100644
--- a/docs/hazmat/primitives/asymmetric/rsa.rst
+++ b/docs/hazmat/primitives/asymmetric/rsa.rst
@@ -154,21 +154,39 @@ RSA
             :class:`~cryptography.hazmat.primitives.asymmetric.padding.OAEP`
             it may also be raised for invalid label values.
 
-        .. code-block:: python
+        .. doctest::
 
-            from cryptography.hazmat.backends import default_backend
-            from cryptography.hazmat.primitives import hashes
-            from cryptography.hazmat.primitives.asymmetric import padding
+            >>> from cryptography.hazmat.backends import default_backend
+            >>> from cryptography.hazmat.primitives import hashes
+            >>> from cryptography.hazmat.primitives.asymmetric import padding
 
-            plaintext = private_key.decrypt(
-                ciphertext,
-                padding.OAEP(
-                    mgf=padding.MGF1(algorithm=hashes.SHA1()),
-                    algorithm=hashes.SHA1(),
-                    label=None
-                ),
-                default_backend()
-            )
+            >>> # Generate a key
+            >>> private_key = rsa.RSAPrivateKey.generate(
+            ...     public_exponent=65537,
+            ...     key_size=2048,
+            ...     backend=default_backend()
+            ... )
+            >>> public_key = private_key.public_key()
+            >>> # encrypt some data
+            >>> ciphertext = public_key.encrypt(
+            ...     b"encrypted data",
+            ...     padding.OAEP(
+            ...         mgf=padding.MGF1(algorithm=hashes.SHA1()),
+            ...         algorithm=hashes.SHA1(),
+            ...         label=None
+            ...     ),
+            ...     default_backend()
+            ... )
+            >>> # Now do the actual decryption
+            >>> plaintext = private_key.decrypt(
+            ...     ciphertext,
+            ...     padding.OAEP(
+            ...         mgf=padding.MGF1(algorithm=hashes.SHA1()),
+            ...         algorithm=hashes.SHA1(),
+            ...         label=None
+            ...     ),
+            ...     default_backend()
+            ... )
 
 
 .. class:: RSAPublicKey(public_exponent, modulus)
@@ -306,27 +324,29 @@ RSA
             :class:`~cryptography.hazmat.primitives.asymmetric.padding.OAEP`
             it may also be raised for invalid label values.
 
-        .. code-block:: python
-
-            from cryptography.hazmat.backends import default_backend
-            from cryptography.hazmat.primitives import hashes
-            from cryptography.hazmat.primitives.asymmetric import padding, rsa
-
-            private_key = rsa.RSAPrivateKey.generate(
-                public_exponent=65537,
-                key_size=2048,
-                backend=default_backend()
-            )
-            public_key = private_key.public_key()
-            ciphertext = public_key.encrypt(
-                plaintext,
-                padding.OAEP(
-                    mgf=padding.MGF1(algorithm=hashes.SHA1()),
-                    algorithm=hashes.SHA1(),
-                    label=None
-                ),
-                default_backend()
-            )
+        .. doctest::
+
+            >>> from cryptography.hazmat.backends import default_backend
+            >>> from cryptography.hazmat.primitives import hashes
+            >>> from cryptography.hazmat.primitives.asymmetric import padding
+
+            >>> # Generate a key
+            >>> private_key = rsa.RSAPrivateKey.generate(
+            ...     public_exponent=65537,
+            ...     key_size=2048,
+            ...     backend=default_backend()
+            ... )
+            >>> public_key = private_key.public_key()
+            >>> # encrypt some data
+            >>> ciphertext = public_key.encrypt(
+            ...     b"encrypted data",
+            ...     padding.OAEP(
+            ...         mgf=padding.MGF1(algorithm=hashes.SHA1()),
+            ...         algorithm=hashes.SHA1(),
+            ...         label=None
+            ...     ),
+            ...     default_backend()
+            ... )
 
 
 Handling partial RSA private keys
diff --git a/tests/hazmat/backends/test_multibackend.py b/tests/hazmat/backends/test_multibackend.py
index fd2a30cd..088465a1 100644
--- a/tests/hazmat/backends/test_multibackend.py
+++ b/tests/hazmat/backends/test_multibackend.py
@@ -98,6 +98,15 @@ class DummyRSABackend(object):
                                     algorithm):
         pass
 
+    def mgf1_hash_supported(self, algorithm):
+        pass
+
+    def decrypt_rsa(self, private_key, ciphertext, padding):
+        pass
+
+    def encrypt_rsa(self, public_key, plaintext, padding):
+        pass
+
 
 @utils.register_interface(DSABackend)
 class DummyDSABackend(object):
@@ -211,6 +220,12 @@ class TestMultiBackend(object):
         backend.create_rsa_verification_ctx("public_key", "sig",
                                             padding.PKCS1v15(), hashes.MD5())
 
+        backend.mgf1_hash_supported(hashes.MD5())
+
+        backend.encrypt_rsa("public_key", "encryptme", padding.PKCS1v15())
+
+        backend.decrypt_rsa("private_key", "encrypted", padding.PKCS1v15())
+
         backend = MultiBackend([])
         with raises_unsupported_algorithm(
             _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM
@@ -229,6 +244,21 @@ class TestMultiBackend(object):
             backend.create_rsa_verification_ctx(
                 "public_key", "sig", padding.PKCS1v15(), hashes.MD5())
 
+        with raises_unsupported_algorithm(
+            _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM
+        ):
+            backend.mgf1_hash_supported(hashes.MD5())
+
+        with raises_unsupported_algorithm(
+            _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM
+        ):
+            backend.encrypt_rsa("public_key", "encryptme", padding.PKCS1v15())
+
+        with raises_unsupported_algorithm(
+            _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM
+        ):
+            backend.decrypt_rsa("private_key", "encrypted", padding.PKCS1v15())
+
     def test_dsa(self):
         backend = MultiBackend([
             DummyDSABackend()