From 4ccceaf4484dce24c5f0994b52079293a5fdb37c Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 11:26:37 -0600
Subject: add RSA PKCS1 signing (and structure for PSS + verification)

---
 cryptography/exceptions.py                         |   4 +
 cryptography/hazmat/backends/openssl/backend.py    | 120 ++++++++++++++++++++-
 .../hazmat/primitives/asymmetric/padding.py        |  22 ++++
 cryptography/hazmat/primitives/asymmetric/rsa.py   |   3 +
 docs/exceptions.rst                                |   6 ++
 docs/hazmat/primitives/asymmetric/index.rst        |  10 ++
 docs/hazmat/primitives/asymmetric/padding.rst      |  20 ++++
 docs/hazmat/primitives/asymmetric/rsa.rst          | 107 ++++++++++++++++++
 docs/hazmat/primitives/index.rst                   |   2 +-
 docs/hazmat/primitives/rsa.rst                     |  77 -------------
 tests/hazmat/primitives/test_rsa.py                |  60 +++++++++++
 11 files changed, 352 insertions(+), 79 deletions(-)
 create mode 100644 cryptography/hazmat/primitives/asymmetric/padding.py
 create mode 100644 docs/hazmat/primitives/asymmetric/index.rst
 create mode 100644 docs/hazmat/primitives/asymmetric/padding.rst
 create mode 100644 docs/hazmat/primitives/asymmetric/rsa.rst
 delete mode 100644 docs/hazmat/primitives/rsa.rst

diff --git a/cryptography/exceptions.py b/cryptography/exceptions.py
index f9849e2f..1144cb94 100644
--- a/cryptography/exceptions.py
+++ b/cryptography/exceptions.py
@@ -46,3 +46,7 @@ class InvalidKey(Exception):
 
 class InvalidToken(Exception):
     pass
+
+
+class UnsupportedAsymmetricPadding(Exception):
+    pass
diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index de6f841c..126d8f0c 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -17,7 +17,8 @@ import itertools
 
 from cryptography import utils
 from cryptography.exceptions import (
-    UnsupportedAlgorithm, InvalidTag, InternalError
+    UnsupportedAlgorithm, InvalidTag, InternalError, AlreadyFinalized,
+    UnsupportedAsymmetricPadding
 )
 from cryptography.hazmat.backends.interfaces import (
     CipherBackend, HashBackend, HMACBackend, PBKDF2HMACBackend, RSABackend
@@ -321,6 +322,30 @@ class Backend(object):
             modulus=self._bn_to_int(ctx.n),
         )
 
+    def _rsa_cdata_from_private_key(self, private_key):
+        ctx = self._lib.RSA_new()
+        assert ctx != self._ffi.NULL
+        ctx = self._ffi.gc(ctx, self._lib.RSA_free)
+        ctx.p = self._int_to_bn(private_key.p)
+        ctx.q = self._int_to_bn(private_key.q)
+        ctx.d = self._int_to_bn(private_key.d)
+        ctx.e = self._int_to_bn(private_key.e)
+        ctx.n = self._int_to_bn(private_key.n)
+        ctx.dmp1 = self._int_to_bn(private_key.dmp1)
+        ctx.dmq1 = self._int_to_bn(private_key.dmq1)
+        ctx.iqmp = self._int_to_bn(private_key.iqmp)
+        return ctx
+
+    def _rsa_cdata_from_public_key(self, public_key):
+        ctx = self._lib.RSA_new()
+        ctx = self._ffi.gc(ctx, self._lib.RSA_free)
+        ctx.e = self._int_to_bn(public_key.e)
+        ctx.n = self._int_to_bn(public_key.n)
+        return ctx
+
+    def create_rsa_signature_ctx(self, private_key, padding, algorithm):
+        return _RSASignatureContext(self, private_key, padding, algorithm)
+
 
 class GetCipherByName(object):
     def __init__(self, fmt):
@@ -572,4 +597,97 @@ class _HMACContext(object):
         return self._backend._ffi.buffer(buf)[:]
 
 
+@utils.register_interface(interfaces.AsymmetricSignatureContext)
+class _RSASignatureContext(object):
+    def __init__(self, backend, private_key, padding, algorithm):
+        self._backend = backend
+        self._private_key = private_key
+        if not isinstance(padding, interfaces.AsymmetricPadding):
+            raise TypeError(
+                "Expected interface of interfaces.AsymmetricPadding")
+
+        if padding.name == "EMSA-PKCS1-v1_5":
+            if self._backend._lib.Cryptography_HAS_PKEY_CTX:
+                self._finalize_method = self._finalize_pkey_ctx
+                self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
+            else:
+                self._finalize_method = self._finalize_pkcs1
+        else:
+            raise UnsupportedAsymmetricPadding
+
+        self._padding = padding
+        self._algorithm = algorithm
+        self._hash_ctx = _HashContext(backend, self._algorithm)
+
+    def update(self, data):
+        if self._hash_ctx is None:
+            raise AlreadyFinalized("Context was already finalized")
+
+        self._hash_ctx.update(data)
+
+    def finalize(self):
+        if self._hash_ctx is None:
+            raise AlreadyFinalized("Context was already finalized")
+        evp_pkey = self._backend._lib.EVP_PKEY_new()
+        assert evp_pkey != self._backend._ffi.NULL
+        evp_pkey = backend._ffi.gc(evp_pkey, backend._lib.EVP_PKEY_free)
+        rsa_cdata = backend._rsa_cdata_from_private_key(self._private_key)
+        res = self._backend._lib.RSA_blinding_on(
+            rsa_cdata, self._backend._ffi.NULL)
+        assert res == 1
+        res = self._backend._lib.EVP_PKEY_set1_RSA(evp_pkey, rsa_cdata)
+        assert res == 1
+        evp_md = self._backend._lib.EVP_get_digestbyname(
+            self._algorithm.name.encode("ascii"))
+        assert evp_md != self._backend._ffi.NULL
+        pkey_size = self._backend._lib.EVP_PKEY_size(evp_pkey)
+        assert pkey_size > 0
+
+        return self._finalize_method(evp_pkey, pkey_size, rsa_cdata, evp_md)
+
+    def _finalize_pkey_ctx(self, evp_pkey, pkey_size, rsa_cdata, evp_md):
+        pkey_ctx = self._backend._lib.EVP_PKEY_CTX_new(
+            evp_pkey, self._backend._ffi.NULL
+        )
+        assert pkey_ctx != self._backend._ffi.NULL
+        res = self._backend._lib.EVP_PKEY_sign_init(pkey_ctx)
+        assert res == 1
+        res = self._backend._lib.EVP_PKEY_CTX_set_signature_md(
+            pkey_ctx, evp_md)
+        assert res > 0
+
+        res = self._backend._lib.EVP_PKEY_CTX_set_rsa_padding(
+            pkey_ctx, self._padding_enum)
+        assert res > 0
+        data_to_sign = self._hash_ctx.finalize()
+        self._hash_ctx = None
+        buflen = self._backend._ffi.new("size_t *")
+        res = self._backend._lib.EVP_PKEY_sign(
+            pkey_ctx,
+            self._backend._ffi.NULL,
+            buflen,
+            data_to_sign,
+            len(data_to_sign)
+        )
+        assert res == 1
+        buf = self._backend._ffi.new("unsigned char[]", buflen[0])
+        res = self._backend._lib.EVP_PKEY_sign(
+            pkey_ctx, buf, buflen, data_to_sign, len(data_to_sign))
+        assert res == 1
+        return self._backend._ffi.buffer(buf)[:]
+
+    def _finalize_pkcs1(self, evp_pkey, pkey_size, rsa_cdata, evp_md):
+        sig_buf = self._backend._ffi.new("char[]", pkey_size)
+        sig_len = self._backend._ffi.new("unsigned int *")
+        res = self._backend._lib.EVP_SignFinal(
+            self._hash_ctx._ctx,
+            sig_buf,
+            sig_len,
+            evp_pkey
+        )
+        self._hash_ctx = None
+        assert res == 1
+        return self._backend._ffi.buffer(sig_buf)[:sig_len[0]]
+
+
 backend = Backend()
diff --git a/cryptography/hazmat/primitives/asymmetric/padding.py b/cryptography/hazmat/primitives/asymmetric/padding.py
new file mode 100644
index 00000000..ca00e94b
--- /dev/null
+++ b/cryptography/hazmat/primitives/asymmetric/padding.py
@@ -0,0 +1,22 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import, division, print_function
+
+from cryptography import utils
+from cryptography.hazmat.primitives import interfaces
+
+
+@utils.register_interface(interfaces.AsymmetricPadding)
+class PKCS1(object):
+    name = "EMSA-PKCS1-v1_5"
diff --git a/cryptography/hazmat/primitives/asymmetric/rsa.py b/cryptography/hazmat/primitives/asymmetric/rsa.py
index 01218592..a63d4308 100644
--- a/cryptography/hazmat/primitives/asymmetric/rsa.py
+++ b/cryptography/hazmat/primitives/asymmetric/rsa.py
@@ -135,6 +135,9 @@ class RSAPrivateKey(object):
     def generate(self, public_exponent, key_size, backend):
         return backend.generate_rsa_private_key(public_exponent, key_size)
 
+    def signer(self, padding, algorithm, backend):
+        return backend.create_rsa_signature_ctx(self, padding, algorithm)
+
     @property
     def key_size(self):
         return _bit_length(self.modulus)
diff --git a/docs/exceptions.rst b/docs/exceptions.rst
index 8ca9df29..38bd0e47 100644
--- a/docs/exceptions.rst
+++ b/docs/exceptions.rst
@@ -42,3 +42,9 @@ Exceptions
 
     This is raised when the verify method of a one time password function's
     computed token does not match the expected token.
+
+
+.. class:: UnsupportedAsymmetricPadding
+
+    This is raised when the chosen asymmetric padding is not supported by the
+    backend.
diff --git a/docs/hazmat/primitives/asymmetric/index.rst b/docs/hazmat/primitives/asymmetric/index.rst
new file mode 100644
index 00000000..10319fad
--- /dev/null
+++ b/docs/hazmat/primitives/asymmetric/index.rst
@@ -0,0 +1,10 @@
+.. hazmat::
+
+Asymmetric Algorithms
+=====================
+
+.. toctree::
+    :maxdepth: 1
+
+    rsa
+    padding
diff --git a/docs/hazmat/primitives/asymmetric/padding.rst b/docs/hazmat/primitives/asymmetric/padding.rst
new file mode 100644
index 00000000..d3f713ae
--- /dev/null
+++ b/docs/hazmat/primitives/asymmetric/padding.rst
@@ -0,0 +1,20 @@
+.. hazmat::
+
+Padding
+=======
+
+.. currentmodule:: cryptography.hazmat.primitives.asymmetric.padding
+
+.. warning::
+    `Padding is critical`_ when signing or encrypting data using RSA. Without
+    correct padding signatures can be forged, messages decrypted, and private
+    keys compromised.
+
+.. class:: PKCS1()
+
+    .. versionadded:: 0.3
+
+    PKCS1 (also known as PKCS1 v1.5) is a simple padding scheme developed for
+    use with RSA keys. It is also defined in :rfc:`3447`.
+
+.. _`Padding is critical`: http://rdist.root.org/2009/10/06/why-rsa-encryption-padding-is-critical/
diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst
new file mode 100644
index 00000000..82cf3528
--- /dev/null
+++ b/docs/hazmat/primitives/asymmetric/rsa.rst
@@ -0,0 +1,107 @@
+.. hazmat::
+
+RSA
+===
+
+.. currentmodule:: cryptography.hazmat.primitives.asymmetric.rsa
+
+`RSA`_ is a `public-key`_ algorithm for encrypting and signing messages.
+
+.. class:: RSAPrivateKey(p, q, private_exponent, dmp1, dmq1, iqmp, public_exponent, modulus)
+
+    .. versionadded:: 0.2
+
+    An RSA private key is required for decryption and signing of messages.
+
+    You should use :meth:`~generate` to generate new keys.
+
+    .. warning::
+        This method only checks a limited set of properties of its arguments.
+        Using an RSA private key that you do not trust or with incorrect
+        parameters may lead to insecure operation, crashes, and other undefined
+        behavior. We recommend that you only ever load private keys that were
+        generated with software you trust.
+
+
+    This class conforms to the
+    :class:`~cryptography.hazmat.primitives.interfaces.RSAPrivateKey`
+    interface.
+
+    :raises TypeError: This is raised when the arguments are not all integers.
+
+    :raises ValueError: This is raised when the values of ``p``, ``q``,
+                        ``private_exponent``, ``public_exponent``, or
+                        ``modulus`` do not match the bounds specified in
+                        :rfc:`3447`.
+
+    .. classmethod:: generate(public_exponent, key_size, backend)
+
+        Generate a new ``RSAPrivateKey`` instance using ``backend``.
+
+        :param int public_exponent: The public exponent of the new key.
+            Usually one of the small Fermat primes 3, 5, 17, 257, 65537. If in
+            doubt you should `use 65537`_.
+        :param int key_size: The length of the modulus in bits. For keys
+            generated in 2014 this should be `at least 2048`_. (See page 41.)
+            Must be at least 512. Some backends may have additional
+            limitations.
+        :param backend: A
+            :class:`~cryptography.hazmat.backends.interfaces.RSABackend`
+            provider.
+        :return: A new instance of ``RSAPrivateKey``.
+
+    .. method:: signer(padding, algorithm, backend)
+
+        .. versionadded:: 0.3
+
+        :param padding: An instance of a
+            :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding`
+            provider.
+
+        :param algorithm: An instance of a
+            :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
+            provider.
+
+        :param backend: A
+            :class:`~cryptography.hazmat.backends.interfaces.RSABackend`
+            provider.
+
+        :returns:
+            :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext`
+
+        .. doctest::
+
+            >>> from cryptography.hazmat.backends import default_backend
+            >>> from cryptography.hazmat.primitives import hashes
+            >>> from cryptography.hazmat.primitives.asymmetric import rsa, padding
+            >>> private_key = rsa.RSAPrivateKey.generate(65537, 2048, default_backend())
+            >>> signer = private_key.signer(padding.PKCS1(), hashes.SHA256(), default_backend())
+            >>> signer.update(b"this is some data I'd like")
+            >>> signer.update(b" to sign")
+            >>> signature = signer.finalize()
+
+
+.. class:: RSAPublicKey(public_exponent, modulus)
+
+    .. versionadded:: 0.2
+
+    An RSA public key is required for encryption and verification of messages.
+
+    Normally you do not need to directly construct public keys because you'll
+    be loading them from a file, generating them automatically or receiving
+    them from a 3rd party.
+
+    This class conforms to the
+    :class:`~cryptography.hazmat.primitives.interfaces.RSAPublicKey`
+    interface.
+
+    :raises TypeError: This is raised when the arguments are not all integers.
+
+    :raises ValueError: This is raised when the values of ``public_exponent``
+                        or ``modulus`` do not match the bounds specified in
+                        :rfc:`3447`.
+
+.. _`RSA`: https://en.wikipedia.org/wiki/RSA_(cryptosystem)
+.. _`public-key`: https://en.wikipedia.org/wiki/Public-key_cryptography
+.. _`use 65537`: http://www.daemonology.net/blog/2009-06-11-cryptographic-right-answers.html
+.. _`at least 2048`: http://www.ecrypt.eu.org/documents/D.SPA.20.pdf
diff --git a/docs/hazmat/primitives/index.rst b/docs/hazmat/primitives/index.rst
index 5199d493..90deec8b 100644
--- a/docs/hazmat/primitives/index.rst
+++ b/docs/hazmat/primitives/index.rst
@@ -11,7 +11,7 @@ Primitives
     symmetric-encryption
     padding
     key-derivation-functions
-    rsa
+    asymmetric/index
     constant-time
     interfaces
     twofactor
diff --git a/docs/hazmat/primitives/rsa.rst b/docs/hazmat/primitives/rsa.rst
deleted file mode 100644
index 4e1f8e49..00000000
--- a/docs/hazmat/primitives/rsa.rst
+++ /dev/null
@@ -1,77 +0,0 @@
-.. hazmat::
-
-RSA
-===
-
-.. currentmodule:: cryptography.hazmat.primitives.asymmetric.rsa
-
-`RSA`_ is a `public-key`_ algorithm for encrypting and signing messages.
-
-.. class:: RSAPrivateKey(p, q, private_exponent, dmp1, dmq1, iqmp, public_exponent, modulus)
-
-    .. versionadded:: 0.2
-
-    An RSA private key is required for decryption and signing of messages.
-
-    You should use :meth:`~generate` to generate new keys.
-
-    .. warning::
-        This method only checks a limited set of properties of its arguments.
-        Using an RSA private key that you do not trust or with incorrect
-        parameters may lead to insecure operation, crashes, and other undefined
-        behavior. We recommend that you only ever load private keys that were
-        generated with software you trust.
-
-
-    This class conforms to the
-    :class:`~cryptography.hazmat.primitives.interfaces.RSAPrivateKey`
-    interface.
-
-    :raises TypeError: This is raised when the arguments are not all integers.
-
-    :raises ValueError: This is raised when the values of ``p``, ``q``,
-                        ``private_exponent``, ``public_exponent``, or
-                        ``modulus`` do not match the bounds specified in
-                        :rfc:`3447`.
-
-    .. classmethod:: generate(public_exponent, key_size, backend)
-
-        Generate a new ``RSAPrivateKey`` instance using ``backend``.
-
-        :param int public_exponent: The public exponent of the new key.
-            Usually one of the small Fermat primes 3, 5, 17, 257, 65537. If in
-            doubt you should `use 65537`_.
-        :param int key_size: The length of the modulus in bits. For keys
-            generated in 2014 this should be `at least 2048`_. (See page 41.)
-            Must be at least 512. Some backends may have additional
-            limitations.
-        :param backend: A
-            :class:`~cryptography.hazmat.backends.interfaces.RSABackend`
-            provider.
-        :return: A new instance of ``RSAPrivateKey``.
-
-
-.. class:: RSAPublicKey(public_exponent, modulus)
-
-    .. versionadded:: 0.2
-
-    An RSA public key is required for encryption and verification of messages.
-
-    Normally you do not need to directly construct public keys because you'll
-    be loading them from a file, generating them automatically or receiving
-    them from a 3rd party.
-
-    This class conforms to the
-    :class:`~cryptography.hazmat.primitives.interfaces.RSAPublicKey`
-    interface.
-
-    :raises TypeError: This is raised when the arguments are not all integers.
-
-    :raises ValueError: This is raised when the values of ``public_exponent``
-                        or ``modulus`` do not match the bounds specified in
-                        :rfc:`3447`.
-
-.. _`RSA`: https://en.wikipedia.org/wiki/RSA_(cryptosystem)
-.. _`public-key`: https://en.wikipedia.org/wiki/Public-key_cryptography
-.. _`use 65537`: http://www.daemonology.net/blog/2009-06-11-cryptographic-right-answers.html
-.. _`at least 2048`: http://www.ecrypt.eu.org/documents/D.SPA.20.pdf
diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index df3a70f5..b2ea9bad 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -14,16 +14,25 @@
 
 from __future__ import absolute_import, division, print_function
 
+import binascii
 import itertools
 import os
 
 import pytest
 
+from cryptography import exceptions, utils
+from cryptography.hazmat.primitives import hashes, interfaces
 from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.hazmat.primitives.asymmetric import padding
 
 from ...utils import load_pkcs1_vectors, load_vectors_from_file
 
 
+@utils.register_interface(interfaces.AsymmetricPadding)
+class FakePadding(object):
+    name = "UNSUPPORTED-PADDING"
+
+
 def _modinv(e, m):
     """
     Modular Multiplicative Inverse.  Returns x such that: (x*e) mod m == 1
@@ -55,6 +64,17 @@ def _check_rsa_private_key(skey):
     assert skey.key_size == pkey.key_size
 
 
+def _flatten_pkcs1_examples(vectors):
+    flattened_vectors = []
+    for vector in vectors:
+        examples = vector[0].pop("examples")
+        for example in examples:
+            merged_vector = (vector[0], vector[1], example)
+            flattened_vectors.append(merged_vector)
+
+    return flattened_vectors
+
+
 def test_modular_inverse():
     p = int(
         "d1f9f6c09fd3d38987f7970247b85a6da84907753d42ec52bc23b745093f4fff5cff3"
@@ -363,3 +383,43 @@ class TestRSA(object):
         # Test a public_exponent that is not odd.
         with pytest.raises(ValueError):
             rsa.RSAPublicKey(public_exponent=6, modulus=15)
+
+
+@pytest.mark.rsa
+class TestRSASignature(object):
+    @pytest.mark.parametrize(
+        "pkcs1_example",
+        _flatten_pkcs1_examples(load_vectors_from_file(
+            os.path.join(
+                "asymmetric", "RSA", "pkcs1v15sign-vectors.txt"),
+            load_pkcs1_vectors
+        ))
+    )
+    def test_pkcs1v15_signing(self, pkcs1_example, backend):
+        private, public, example = pkcs1_example
+        private_key = rsa.RSAPrivateKey(**private)
+        public_key = rsa.RSAPublicKey(**public)
+        signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
+        signer.update(binascii.unhexlify(example["message"]))
+        signature = signer.finalize()
+        assert binascii.hexlify(signature) == example["signature"]
+
+    def test_use_after_finalize(self, backend):
+        private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
+        signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
+        signer.update(b"sign me")
+        signer.finalize()
+        with pytest.raises(exceptions.AlreadyFinalized):
+            signer.finalize()
+        with pytest.raises(exceptions.AlreadyFinalized):
+            signer.update(b"more data")
+
+    def test_unsupported_padding(self, backend):
+        private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
+        with pytest.raises(exceptions.UnsupportedAsymmetricPadding):
+            private_key.signer(FakePadding(), hashes.SHA1(), backend)
+
+    def test_padding_incorrect_type(self, backend):
+        private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
+        with pytest.raises(TypeError):
+            private_key.signer("notpadding", hashes.SHA1(), backend)
-- 
cgit v1.2.3


From da19e2b59957870fdb04e1027a9221b8fa2c810e Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 11:42:03 -0600
Subject: some style fixes

---
 tests/hazmat/primitives/test_rsa.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index b2ea9bad..11fb3729 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -29,7 +29,7 @@ from ...utils import load_pkcs1_vectors, load_vectors_from_file
 
 
 @utils.register_interface(interfaces.AsymmetricPadding)
-class FakePadding(object):
+class DummyPadding(object):
     name = "UNSUPPORTED-PADDING"
 
 
@@ -415,9 +415,13 @@ class TestRSASignature(object):
             signer.update(b"more data")
 
     def test_unsupported_padding(self, backend):
-        private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
+        private_key = rsa.RSAPrivateKey.generate(
+            public_exponent=65537,
+            key_size=512,
+            backend=backend
+        )
         with pytest.raises(exceptions.UnsupportedAsymmetricPadding):
-            private_key.signer(FakePadding(), hashes.SHA1(), backend)
+            private_key.signer(DummyPadding(), hashes.SHA1(), backend)
 
     def test_padding_incorrect_type(self, backend):
         private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
-- 
cgit v1.2.3


From a33df8ed655b507e72bdb4aab377dcf7a81954c5 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 15:05:37 -0600
Subject: fix pep8

---
 tests/hazmat/primitives/test_rsa.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index 11fb3729..8229b76b 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -398,7 +398,6 @@ class TestRSASignature(object):
     def test_pkcs1v15_signing(self, pkcs1_example, backend):
         private, public, example = pkcs1_example
         private_key = rsa.RSAPrivateKey(**private)
-        public_key = rsa.RSAPublicKey(**public)
         signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
         signer.update(binascii.unhexlify(example["message"]))
         signature = signer.finalize()
-- 
cgit v1.2.3


From dff1d43d0ae65da599eb60f99d411112b39fc8e9 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 15:09:56 -0600
Subject: add basic multibackend so we can do signatures using default_backend

---
 cryptography/hazmat/backends/multibackend.py |  7 +++++++
 tests/hazmat/backends/test_multibackend.py   | 11 +++++++++++
 2 files changed, 18 insertions(+)

diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py
index 4de02026..eb58dd68 100644
--- a/cryptography/hazmat/backends/multibackend.py
+++ b/cryptography/hazmat/backends/multibackend.py
@@ -24,6 +24,7 @@ from cryptography.hazmat.backends.interfaces import (
 @utils.register_interface(HashBackend)
 @utils.register_interface(HMACBackend)
 @utils.register_interface(PBKDF2HMACBackend)
+@utils.register_interface(RSABackend)
 class MultiBackend(object):
     name = "multibackend"
 
@@ -106,3 +107,9 @@ class MultiBackend(object):
         for b in self._filtered_backends(RSABackend):
             return b.generate_rsa_private_key(public_exponent, key_size)
         raise UnsupportedAlgorithm
+
+    def create_rsa_signature_ctx(self, private_key, padding, algorithm):
+        for b in self._filtered_backends(RSABackend):
+            return b.create_rsa_signature_ctx(private_key, padding, algorithm)
+        raise UnsupportedAlgorithm
+
diff --git a/tests/hazmat/backends/test_multibackend.py b/tests/hazmat/backends/test_multibackend.py
index ce77ce2f..e3f83d3a 100644
--- a/tests/hazmat/backends/test_multibackend.py
+++ b/tests/hazmat/backends/test_multibackend.py
@@ -20,6 +20,7 @@ from cryptography.hazmat.backends.interfaces import (
 )
 from cryptography.hazmat.backends.multibackend import MultiBackend
 from cryptography.hazmat.primitives import hashes, hmac
+from cryptography.hazmat.primitives.asymmetric import padding
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
 
 
@@ -85,6 +86,9 @@ class DummyRSABackend(object):
     def generate_rsa_private_key(self, public_exponent, private_key):
         pass
 
+    def create_rsa_signature_ctx(self, private_key, padding, algorithm):
+        pass
+
 
 class TestMultiBackend(object):
     def test_ciphers(self):
@@ -158,6 +162,13 @@ class TestMultiBackend(object):
             key_size=1024, public_exponent=65537
         )
 
+        backend.create_rsa_signature_ctx("private_key", padding.PKCS1(),
+                                         hashes.MD5())
+
         backend = MultiBackend([])
         with pytest.raises(UnsupportedAlgorithm):
             backend.generate_rsa_private_key(key_size=1024, public_exponent=3)
+
+        with pytest.raises(UnsupportedAlgorithm):
+            backend.create_rsa_signature_ctx("private_key", padding.PKCS1(),
+                                             hashes.MD5())
-- 
cgit v1.2.3


From 0849575a216238410853f97780bb8646688078b9 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 15:11:14 -0600
Subject: keyword args

---
 tests/hazmat/primitives/test_rsa.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index 8229b76b..14c3acf0 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -404,7 +404,11 @@ class TestRSASignature(object):
         assert binascii.hexlify(signature) == example["signature"]
 
     def test_use_after_finalize(self, backend):
-        private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
+        private_key = rsa.RSAPrivateKey.generate(
+            public_exponent=65537,
+            key_size=512,
+            backend=backend
+        )
         signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
         signer.update(b"sign me")
         signer.finalize()
-- 
cgit v1.2.3


From 0d6722a1ef6ad504d4f669f9d7a8c0952a38445b Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 15:58:09 -0600
Subject: more pep8

---
 cryptography/hazmat/backends/multibackend.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py
index eb58dd68..f0017191 100644
--- a/cryptography/hazmat/backends/multibackend.py
+++ b/cryptography/hazmat/backends/multibackend.py
@@ -112,4 +112,3 @@ class MultiBackend(object):
         for b in self._filtered_backends(RSABackend):
             return b.create_rsa_signature_ctx(private_key, padding, algorithm)
         raise UnsupportedAlgorithm
-
-- 
cgit v1.2.3


From 160e51a207db264c48162b02e22005356100a396 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 17:57:06 -0600
Subject: remove rsa_cdata_from_public_key (unused until verify PR)

---
 cryptography/hazmat/backends/openssl/backend.py | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index 126d8f0c..64f8dc25 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -336,13 +336,6 @@ class Backend(object):
         ctx.iqmp = self._int_to_bn(private_key.iqmp)
         return ctx
 
-    def _rsa_cdata_from_public_key(self, public_key):
-        ctx = self._lib.RSA_new()
-        ctx = self._ffi.gc(ctx, self._lib.RSA_free)
-        ctx.e = self._int_to_bn(public_key.e)
-        ctx.n = self._int_to_bn(public_key.n)
-        return ctx
-
     def create_rsa_signature_ctx(self, private_key, padding, algorithm):
         return _RSASignatureContext(self, private_key, padding, algorithm)
 
-- 
cgit v1.2.3


From 8dd9713ae2a69a3e870275c088df08ce2a50dce9 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Sun, 23 Feb 2014 19:26:05 -0600
Subject: incorporate review feedback. kwarg!

---
 docs/hazmat/primitives/asymmetric/rsa.rst |  6 +++++-
 tests/hazmat/primitives/test_rsa.py       | 11 ++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst
index 82cf3528..5e71c7c8 100644
--- a/docs/hazmat/primitives/asymmetric/rsa.rst
+++ b/docs/hazmat/primitives/asymmetric/rsa.rst
@@ -74,7 +74,11 @@ RSA
             >>> from cryptography.hazmat.backends import default_backend
             >>> from cryptography.hazmat.primitives import hashes
             >>> from cryptography.hazmat.primitives.asymmetric import rsa, padding
-            >>> private_key = rsa.RSAPrivateKey.generate(65537, 2048, default_backend())
+            >>> private_key = rsa.RSAPrivateKey.generate(
+            ...     public_exponent=65537,
+            ...     key_size=2048,
+            ...     backend=default_backend()
+            ... )
             >>> signer = private_key.signer(padding.PKCS1(), hashes.SHA256(), default_backend())
             >>> signer.update(b"this is some data I'd like")
             >>> signer.update(b" to sign")
diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index 14c3acf0..d190ea95 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -397,7 +397,16 @@ class TestRSASignature(object):
     )
     def test_pkcs1v15_signing(self, pkcs1_example, backend):
         private, public, example = pkcs1_example
-        private_key = rsa.RSAPrivateKey(**private)
+        private_key = rsa.RSAPrivateKey(
+            p=private["p"],
+            q=private["q"],
+            private_exponent=private["private_exponent"],
+            dmp1=private["dmp1"],
+            dmq1=private["dmq1"],
+            iqmp=private["iqmp"],
+            public_exponent=private["public_exponent"],
+            modulus=private["modulus"]
+        )
         signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
         signer.update(binascii.unhexlify(example["message"]))
         signature = signer.finalize()
-- 
cgit v1.2.3


From 0377f5a78de949f2f1e719ac89cf8b98b910bf81 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Mon, 24 Feb 2014 19:04:46 -0600
Subject: rename PKCS1->PKCS1v15 &
 UnsupportedAsymmetricPadding->UnsupportedPadding

---
 cryptography/exceptions.py                           | 2 +-
 cryptography/hazmat/primitives/asymmetric/padding.py | 2 +-
 docs/exceptions.rst                                  | 5 ++---
 docs/hazmat/primitives/asymmetric/padding.rst        | 6 +++---
 docs/hazmat/primitives/asymmetric/rsa.rst            | 2 +-
 tests/hazmat/primitives/test_rsa.py                  | 6 +++---
 6 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/cryptography/exceptions.py b/cryptography/exceptions.py
index 1144cb94..b4962591 100644
--- a/cryptography/exceptions.py
+++ b/cryptography/exceptions.py
@@ -48,5 +48,5 @@ class InvalidToken(Exception):
     pass
 
 
-class UnsupportedAsymmetricPadding(Exception):
+class UnsupportedPadding(Exception):
     pass
diff --git a/cryptography/hazmat/primitives/asymmetric/padding.py b/cryptography/hazmat/primitives/asymmetric/padding.py
index ca00e94b..6bafe314 100644
--- a/cryptography/hazmat/primitives/asymmetric/padding.py
+++ b/cryptography/hazmat/primitives/asymmetric/padding.py
@@ -18,5 +18,5 @@ from cryptography.hazmat.primitives import interfaces
 
 
 @utils.register_interface(interfaces.AsymmetricPadding)
-class PKCS1(object):
+class PKCS1v15(object):
     name = "EMSA-PKCS1-v1_5"
diff --git a/docs/exceptions.rst b/docs/exceptions.rst
index 38bd0e47..0982426f 100644
--- a/docs/exceptions.rst
+++ b/docs/exceptions.rst
@@ -44,7 +44,6 @@ Exceptions
     computed token does not match the expected token.
 
 
-.. class:: UnsupportedAsymmetricPadding
+.. class:: UnsupportedPadding
 
-    This is raised when the chosen asymmetric padding is not supported by the
-    backend.
+    This is raised when the chosen padding is not supported by the backend.
diff --git a/docs/hazmat/primitives/asymmetric/padding.rst b/docs/hazmat/primitives/asymmetric/padding.rst
index d3f713ae..7aec3bd3 100644
--- a/docs/hazmat/primitives/asymmetric/padding.rst
+++ b/docs/hazmat/primitives/asymmetric/padding.rst
@@ -10,11 +10,11 @@ Padding
     correct padding signatures can be forged, messages decrypted, and private
     keys compromised.
 
-.. class:: PKCS1()
+.. class:: PKCS1v15()
 
     .. versionadded:: 0.3
 
-    PKCS1 (also known as PKCS1 v1.5) is a simple padding scheme developed for
-    use with RSA keys. It is also defined in :rfc:`3447`.
+    PKCS1 v1.5 (also known as simply PKCS1) is a simple padding scheme
+    developed for use with RSA keys. It is defined in :rfc:`3447`.
 
 .. _`Padding is critical`: http://rdist.root.org/2009/10/06/why-rsa-encryption-padding-is-critical/
diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst
index 5e71c7c8..64928878 100644
--- a/docs/hazmat/primitives/asymmetric/rsa.rst
+++ b/docs/hazmat/primitives/asymmetric/rsa.rst
@@ -79,7 +79,7 @@ RSA
             ...     key_size=2048,
             ...     backend=default_backend()
             ... )
-            >>> signer = private_key.signer(padding.PKCS1(), hashes.SHA256(), default_backend())
+            >>> signer = private_key.signer(padding.PKCS1v15(), hashes.SHA256(), default_backend())
             >>> signer.update(b"this is some data I'd like")
             >>> signer.update(b" to sign")
             >>> signature = signer.finalize()
diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index d190ea95..c66a1581 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -407,7 +407,7 @@ class TestRSASignature(object):
             public_exponent=private["public_exponent"],
             modulus=private["modulus"]
         )
-        signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
+        signer = private_key.signer(padding.PKCS1v15(), hashes.SHA1(), backend)
         signer.update(binascii.unhexlify(example["message"]))
         signature = signer.finalize()
         assert binascii.hexlify(signature) == example["signature"]
@@ -418,7 +418,7 @@ class TestRSASignature(object):
             key_size=512,
             backend=backend
         )
-        signer = private_key.signer(padding.PKCS1(), hashes.SHA1(), backend)
+        signer = private_key.signer(padding.PKCS1v15(), hashes.SHA1(), backend)
         signer.update(b"sign me")
         signer.finalize()
         with pytest.raises(exceptions.AlreadyFinalized):
@@ -432,7 +432,7 @@ class TestRSASignature(object):
             key_size=512,
             backend=backend
         )
-        with pytest.raises(exceptions.UnsupportedAsymmetricPadding):
+        with pytest.raises(exceptions.UnsupportedPadding):
             private_key.signer(DummyPadding(), hashes.SHA1(), backend)
 
     def test_padding_incorrect_type(self, backend):
-- 
cgit v1.2.3


From 8584d6066ae50a0c9917d409df994e469f3fbbee Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Mon, 24 Feb 2014 19:05:52 -0600
Subject: change the rest of the UnsupportedAsymmetricPadding instances

---
 cryptography/hazmat/backends/openssl/backend.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index 64f8dc25..d7c90a8d 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -18,7 +18,7 @@ import itertools
 from cryptography import utils
 from cryptography.exceptions import (
     UnsupportedAlgorithm, InvalidTag, InternalError, AlreadyFinalized,
-    UnsupportedAsymmetricPadding
+    UnsupportedPadding
 )
 from cryptography.hazmat.backends.interfaces import (
     CipherBackend, HashBackend, HMACBackend, PBKDF2HMACBackend, RSABackend
@@ -606,7 +606,7 @@ class _RSASignatureContext(object):
             else:
                 self._finalize_method = self._finalize_pkcs1
         else:
-            raise UnsupportedAsymmetricPadding
+            raise UnsupportedPadding
 
         self._padding = padding
         self._algorithm = algorithm
-- 
cgit v1.2.3


From bfba58bf535048d9b29fd2b7b6044695aa02a4c7 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Mon, 24 Feb 2014 19:32:57 -0600
Subject: update multibackend with new PKCS1v15 class name

---
 tests/hazmat/backends/test_multibackend.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/hazmat/backends/test_multibackend.py b/tests/hazmat/backends/test_multibackend.py
index e3f83d3a..be1e76e2 100644
--- a/tests/hazmat/backends/test_multibackend.py
+++ b/tests/hazmat/backends/test_multibackend.py
@@ -162,7 +162,7 @@ class TestMultiBackend(object):
             key_size=1024, public_exponent=65537
         )
 
-        backend.create_rsa_signature_ctx("private_key", padding.PKCS1(),
+        backend.create_rsa_signature_ctx("private_key", padding.PKCS1v15(),
                                          hashes.MD5())
 
         backend = MultiBackend([])
@@ -170,5 +170,5 @@ class TestMultiBackend(object):
             backend.generate_rsa_private_key(key_size=1024, public_exponent=3)
 
         with pytest.raises(UnsupportedAlgorithm):
-            backend.create_rsa_signature_ctx("private_key", padding.PKCS1(),
+            backend.create_rsa_signature_ctx("private_key", padding.PKCS1v15(),
                                              hashes.MD5())
-- 
cgit v1.2.3


From 49e4c9c4f72311070aa444d7c35cfc27453e4ad9 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Mon, 24 Feb 2014 21:21:08 -0600
Subject: more kwargs

---
 tests/hazmat/primitives/test_rsa.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index c66a1581..647c51b4 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -436,6 +436,10 @@ class TestRSASignature(object):
             private_key.signer(DummyPadding(), hashes.SHA1(), backend)
 
     def test_padding_incorrect_type(self, backend):
-        private_key = rsa.RSAPrivateKey.generate(65537, 512, backend)
+        private_key = rsa.RSAPrivateKey.generate(
+            public_exponent=65537,
+            key_size=512,
+            backend=backend
+        )
         with pytest.raises(TypeError):
             private_key.signer("notpadding", hashes.SHA1(), backend)
-- 
cgit v1.2.3


From c5b4d7239614ce3718a05601184276ca2691c84e Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Tue, 25 Feb 2014 13:17:34 -0600
Subject: address review comments

---
 cryptography/hazmat/backends/openssl/backend.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index d7c90a8d..61bfe624 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -606,7 +606,9 @@ class _RSASignatureContext(object):
             else:
                 self._finalize_method = self._finalize_pkcs1
         else:
-            raise UnsupportedPadding
+            raise UnsupportedPadding(
+                "{0} is not supported by this backend".format(padding.name)
+            )
 
         self._padding = padding
         self._algorithm = algorithm
@@ -678,6 +680,7 @@ class _RSASignatureContext(object):
             sig_len,
             evp_pkey
         )
+        self._hash_ctx.finalize()
         self._hash_ctx = None
         assert res == 1
         return self._backend._ffi.buffer(sig_buf)[:sig_len[0]]
-- 
cgit v1.2.3


From 62a9217aa3f6cf34d4cafcd1d147082bc7c7918c Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Tue, 25 Feb 2014 13:56:53 -0600
Subject: reorganize docs slightly

---
 docs/hazmat/primitives/asymmetric/rsa.rst | 36 ++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/docs/hazmat/primitives/asymmetric/rsa.rst b/docs/hazmat/primitives/asymmetric/rsa.rst
index 64928878..682820b3 100644
--- a/docs/hazmat/primitives/asymmetric/rsa.rst
+++ b/docs/hazmat/primitives/asymmetric/rsa.rst
@@ -54,20 +54,7 @@ RSA
 
         .. versionadded:: 0.3
 
-        :param padding: An instance of a
-            :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding`
-            provider.
-
-        :param algorithm: An instance of a
-            :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
-            provider.
-
-        :param backend: A
-            :class:`~cryptography.hazmat.backends.interfaces.RSABackend`
-            provider.
-
-        :returns:
-            :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext`
+        Sign data which can be verified later by others using the public key.
 
         .. doctest::
 
@@ -79,11 +66,30 @@ RSA
             ...     key_size=2048,
             ...     backend=default_backend()
             ... )
-            >>> signer = private_key.signer(padding.PKCS1v15(), hashes.SHA256(), default_backend())
+            >>> signer = private_key.signer(
+            ...     padding.PKCS1v15(),
+            ...     hashes.SHA256(),
+            ...     default_backend()
+            ... )
             >>> signer.update(b"this is some data I'd like")
             >>> signer.update(b" to sign")
             >>> signature = signer.finalize()
 
+        :param padding: An instance of a
+            :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricPadding`
+            provider.
+
+        :param algorithm: An instance of a
+            :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
+            provider.
+
+        :param backend: A
+            :class:`~cryptography.hazmat.backends.interfaces.RSABackend`
+            provider.
+
+        :returns:
+            :class:`~cryptography.hazmat.primitives.interfaces.AsymmetricSignatureContext`
+
 
 .. class:: RSAPublicKey(public_exponent, modulus)
 
-- 
cgit v1.2.3


From 572cb46dcca8d1b06f44ab2135f866002b3e32e2 Mon Sep 17 00:00:00 2001
From: Paul Kehrer <paul.l.kehrer@gmail.com>
Date: Tue, 25 Feb 2014 18:03:03 -0600
Subject: some error msg improvements

---
 cryptography/hazmat/backends/openssl/backend.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index 61bfe624..00fdc266 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -597,7 +597,7 @@ class _RSASignatureContext(object):
         self._private_key = private_key
         if not isinstance(padding, interfaces.AsymmetricPadding):
             raise TypeError(
-                "Expected interface of interfaces.AsymmetricPadding")
+                "Expected provider of interfaces.AsymmetricPadding")
 
         if padding.name == "EMSA-PKCS1-v1_5":
             if self._backend._lib.Cryptography_HAS_PKEY_CTX:
@@ -616,13 +616,13 @@ class _RSASignatureContext(object):
 
     def update(self, data):
         if self._hash_ctx is None:
-            raise AlreadyFinalized("Context was already finalized")
+            raise AlreadyFinalized("Context has already been finalized")
 
         self._hash_ctx.update(data)
 
     def finalize(self):
         if self._hash_ctx is None:
-            raise AlreadyFinalized("Context was already finalized")
+            raise AlreadyFinalized("Context has already been finalized")
         evp_pkey = self._backend._lib.EVP_PKEY_new()
         assert evp_pkey != self._backend._ffi.NULL
         evp_pkey = backend._ffi.gc(evp_pkey, backend._lib.EVP_PKEY_free)
-- 
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