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author | Paul Kehrer <paul.l.kehrer@gmail.com> | 2014-04-05 08:55:09 -0500 |
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committer | Paul Kehrer <paul.l.kehrer@gmail.com> | 2014-04-05 08:55:09 -0500 |
commit | 6abaf40a591bbae5e2eeebb8a29e6558aeae047c (patch) | |
tree | 5e2a7de8ca3c3f32da66773fcf24a45555e57cd7 | |
parent | 509343e400942e78f5c1d0d5f380002939b24266 (diff) | |
parent | 29474ac7dab3f5c8b664463ed28ec83b7b77250b (diff) | |
download | cryptography-6abaf40a591bbae5e2eeebb8a29e6558aeae047c.tar.gz cryptography-6abaf40a591bbae5e2eeebb8a29e6558aeae047c.tar.bz2 cryptography-6abaf40a591bbae5e2eeebb8a29e6558aeae047c.zip |
Merge pull request #739 from skeuomorf/dsa-backend
DSA backend
-rw-r--r-- | cryptography/hazmat/backends/interfaces.py | 15 | ||||
-rw-r--r-- | cryptography/hazmat/backends/multibackend.py | 16 | ||||
-rw-r--r-- | cryptography/hazmat/backends/openssl/backend.py | 52 | ||||
-rw-r--r-- | cryptography/hazmat/primitives/asymmetric/dsa.py | 22 | ||||
-rw-r--r-- | docs/hazmat/backends/interfaces.rst | 34 | ||||
-rw-r--r-- | docs/hazmat/primitives/asymmetric/dsa.rst | 59 | ||||
-rw-r--r-- | pytest.ini | 1 | ||||
-rw-r--r-- | tests/conftest.py | 4 | ||||
-rw-r--r-- | tests/hazmat/backends/test_multibackend.py | 33 | ||||
-rw-r--r-- | tests/hazmat/backends/test_openssl.py | 25 | ||||
-rw-r--r-- | tests/hazmat/primitives/test_dsa.py | 50 |
11 files changed, 304 insertions, 7 deletions
diff --git a/cryptography/hazmat/backends/interfaces.py b/cryptography/hazmat/backends/interfaces.py index 27b609ed..20c21118 100644 --- a/cryptography/hazmat/backends/interfaces.py +++ b/cryptography/hazmat/backends/interfaces.py @@ -113,6 +113,21 @@ class RSABackend(six.with_metaclass(abc.ABCMeta)): """ +class DSABackend(six.with_metaclass(abc.ABCMeta)): + @abc.abstractmethod + def generate_dsa_parameters(self, key_size): + """ + Generate a DSAParameters instance with a modulus of key_size bits. + """ + + @abc.abstractmethod + def generate_dsa_private_key(self, parameters): + """ + Generate an DSAPrivateKey instance with parameters as + a DSAParameters object. + """ + + class OpenSSLSerializationBackend(six.with_metaclass(abc.ABCMeta)): @abc.abstractmethod def load_openssl_pem_private_key(self, data, password): diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py index aa649dd3..86cded85 100644 --- a/cryptography/hazmat/backends/multibackend.py +++ b/cryptography/hazmat/backends/multibackend.py @@ -16,7 +16,8 @@ from __future__ import absolute_import, division, print_function from cryptography import utils from cryptography.exceptions import UnsupportedAlgorithm, _Reasons from cryptography.hazmat.backends.interfaces import ( - CipherBackend, HMACBackend, HashBackend, PBKDF2HMACBackend, RSABackend + CipherBackend, DSABackend, HMACBackend, HashBackend, PBKDF2HMACBackend, + RSABackend ) @@ -25,6 +26,7 @@ from cryptography.hazmat.backends.interfaces import ( @utils.register_interface(HMACBackend) @utils.register_interface(PBKDF2HMACBackend) @utils.register_interface(RSABackend) +@utils.register_interface(DSABackend) class MultiBackend(object): name = "multibackend" @@ -142,3 +144,15 @@ class MultiBackend(object): padding, algorithm) 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) + raise UnsupportedAlgorithm("DSA is not supported by the backend", + _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM) + + def generate_dsa_private_key(self, parameters): + for b in self._filtered_backends(DSABackend): + return b.generate_dsa_private_key(parameters) + raise UnsupportedAlgorithm("DSA is not supported by the backend", + _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM) diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py index 0c632aee..900d25c2 100644 --- a/cryptography/hazmat/backends/openssl/backend.py +++ b/cryptography/hazmat/backends/openssl/backend.py @@ -25,11 +25,12 @@ from cryptography.exceptions import ( UnsupportedAlgorithm, _Reasons ) from cryptography.hazmat.backends.interfaces import ( - CipherBackend, HMACBackend, HashBackend, PBKDF2HMACBackend, RSABackend + CipherBackend, DSABackend, HMACBackend, HashBackend, PBKDF2HMACBackend, + RSABackend ) from cryptography.hazmat.bindings.openssl.binding import Binding from cryptography.hazmat.primitives import hashes, interfaces -from cryptography.hazmat.primitives.asymmetric import rsa +from cryptography.hazmat.primitives.asymmetric import dsa, rsa from cryptography.hazmat.primitives.asymmetric.padding import ( MGF1, PKCS1v15, PSS ) @@ -46,6 +47,7 @@ _OpenSSLError = collections.namedtuple("_OpenSSLError", @utils.register_interface(CipherBackend) +@utils.register_interface(DSABackend) @utils.register_interface(HashBackend) @utils.register_interface(HMACBackend) @utils.register_interface(PBKDF2HMACBackend) @@ -415,6 +417,52 @@ class Backend(object): else: return isinstance(algorithm, hashes.SHA1) + def generate_dsa_parameters(self, key_size): + if key_size not in (1024, 2048, 3072): + raise ValueError( + "Key size must be 1024 or 2048 or 3072 bits") + + if (self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f and + key_size > 1024): + raise ValueError( + "Key size must be 1024 because OpenSSL < 1.0.0 doesn't " + "support larger key sizes") + + ctx = self._lib.DSA_new() + assert ctx != self._ffi.NULL + ctx = self._ffi.gc(ctx, self._lib.DSA_free) + + res = self._lib.DSA_generate_parameters_ex( + ctx, key_size, self._ffi.NULL, 0, + self._ffi.NULL, self._ffi.NULL, self._ffi.NULL + ) + + assert res == 1 + + return dsa.DSAParameters( + modulus=self._bn_to_int(ctx.p), + subgroup_order=self._bn_to_int(ctx.q), + generator=self._bn_to_int(ctx.g) + ) + + def generate_dsa_private_key(self, parameters): + ctx = self._lib.DSA_new() + assert ctx != self._ffi.NULL + ctx = self._ffi.gc(ctx, self._lib.DSA_free) + ctx.p = self._int_to_bn(parameters.p) + ctx.q = self._int_to_bn(parameters.q) + ctx.g = self._int_to_bn(parameters.g) + + self._lib.DSA_generate_key(ctx) + + return dsa.DSAPrivateKey( + modulus=self._bn_to_int(ctx.p), + subgroup_order=self._bn_to_int(ctx.q), + generator=self._bn_to_int(ctx.g), + x=self._bn_to_int(ctx.priv_key), + y=self._bn_to_int(ctx.pub_key) + ) + class GetCipherByName(object): def __init__(self, fmt): diff --git a/cryptography/hazmat/primitives/asymmetric/dsa.py b/cryptography/hazmat/primitives/asymmetric/dsa.py index 974db0a6..4c2de36a 100644 --- a/cryptography/hazmat/primitives/asymmetric/dsa.py +++ b/cryptography/hazmat/primitives/asymmetric/dsa.py @@ -16,6 +16,8 @@ from __future__ import absolute_import, division, print_function import six from cryptography import utils +from cryptography.exceptions import UnsupportedAlgorithm, _Reasons +from cryptography.hazmat.backends.interfaces import DSABackend from cryptography.hazmat.primitives import interfaces @@ -49,6 +51,16 @@ class DSAParameters(object): self._subgroup_order = subgroup_order self._generator = generator + @classmethod + def generate(cls, key_size, backend): + if not isinstance(backend, DSABackend): + raise UnsupportedAlgorithm( + "Backend object does not implement DSABackend", + _Reasons.BACKEND_MISSING_INTERFACE + ) + + return backend.generate_dsa_parameters(key_size) + @property def modulus(self): return self._modulus @@ -96,6 +108,16 @@ class DSAPrivateKey(object): self._x = x self._y = y + @classmethod + def generate(cls, parameters, backend): + if not isinstance(backend, DSABackend): + raise UnsupportedAlgorithm( + "Backend object does not implement DSABackend", + _Reasons.BACKEND_MISSING_INTERFACE + ) + + return backend.generate_dsa_private_key(parameters) + @property def key_size(self): return utils.bit_length(self._modulus) diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst index c38f818f..9c401d28 100644 --- a/docs/hazmat/backends/interfaces.rst +++ b/docs/hazmat/backends/interfaces.rst @@ -285,3 +285,37 @@ A specific ``backend`` may provide one or more of these interfaces. :raises cryptography.exceptions.UnsupportedAlgorithm: If the data is encrypted with an unsupported algorithm. + + +.. class:: DSABackend + + .. versionadded:: 0.4 + + A backend with methods for using DSA. + + .. method:: generate_dsa_parameters(key_size) + + :param int key_size: The length of the modulus in bits. It should be + either "1024, 2048 or 3072". For keys generated in 2014 this should + be at least 2048. + Note that some applications (such as SSH) have not yet gained support + for larger key sizes specified in FIPS 186-3 and are still restricted + to only the 1024-bit keys specified in FIPS 186-2. + + :return: A new instance of a + :class:`~cryptography.hazmat.primitives.interfaces.DSAParameters` + provider. + + .. method:: generate_dsa_private_key(parameters) + + :param parameters: A + :class:`~cryptography.hazmat.primitives.interfaces.DSAParameters` + provider. + + :return: A new instance of a + :class:`~cryptography.hazmat.primitives.interfaces.DSAPrivateKey` + provider. + + :raises ValueError: This is raised if the key size is not (1024 or 2048 or 3072) + or if the OpenSSL version is older than 1.0.0 and the key size is larger than 1024 + because older OpenSSL versions don't support a key size larger than 1024. diff --git a/docs/hazmat/primitives/asymmetric/dsa.rst b/docs/hazmat/primitives/asymmetric/dsa.rst index 69e8d58e..1a6a6e0e 100644 --- a/docs/hazmat/primitives/asymmetric/dsa.rst +++ b/docs/hazmat/primitives/asymmetric/dsa.rst @@ -13,6 +13,16 @@ DSA DSA Parameters are required for generating a DSA private key. + You should use :meth:`~generate` to generate new parameters. + + .. warning:: + This method only checks a limited set of properties of its arguments. + Using DSA parameters that you do not trust or with incorrect arguments + may lead to insecure operation, crashes, and other undefined behavior. + We recommend that you only ever load parameters that were generated + with software you trust. + + This class conforms to the :class:`~cryptography.hazmat.primitives.interfaces.DSAParameters` interface. @@ -23,6 +33,23 @@ DSA ``subgroup_order``, or ``generator`` do not match the bounds specified in `FIPS 186-4`_. + .. classmethod:: generate(key_size, backend) + + Generate a new ``DSAParameters`` instance using ``backend``. + + :param int key_size: The length of the modulus in bits. It should be + either "1024, 2048 or 3072". For keys generated in 2014 this should + be `at least 2048`_ (See page 41). + Note that some applications (such as SSH) have not yet gained support + for larger key sizes specified in FIPS 186-3 and are still restricted + to only the 1024-bit keys specified in FIPS 186-2. + + :return: A new instance of ``DSAParameters`` + + :raises cryptography.exceptions.UnsupportedAlgorithm: This is raised if + the provided ``backend`` does not implement + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + .. class:: DSAPrivateKey(modulus, subgroup_order, generator, x, y) @@ -30,6 +57,16 @@ DSA A DSA private key is required for signing messages. + You should use :meth:`~generate` to generate new keys. + + .. warning:: + This method only checks a limited set of properties of its arguments. + Using a DSA 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.DSAPrivateKey` interface. @@ -40,6 +77,26 @@ DSA ``subgroup_order``, or ``generator`` do not match the bounds specified in `FIPS 186-4`_. + .. classmethod:: generate(parameters, backend) + + Generate a new ``DSAPrivateKey`` instance using ``backend``. + + :param parameters: A + :class:`~cryptography.hazmat.primitives.interfaces.DSAParameters` + provider. + :param backend: A + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + provider. + :return: A new instance of ``DSAPrivateKey``. + + :raises cryptography.exceptions.UnsupportedAlgorithm: This is raised if + the provided ``backend`` does not implement + :class:`~cryptography.hazmat.backends.interfaces.DSABackend` + + :raises ValueError: This is raised if the key size is not (1024 or 2048 or 3072) + or if the OpenSSL version is older than 1.0.0 and the key size is larger than 1024 + because older OpenSSL versions don't support a key size larger than 1024. + .. class:: DSAPublicKey(modulus, subgroup_order, generator, y) @@ -65,4 +122,4 @@ DSA .. _`DSA`: https://en.wikipedia.org/wiki/Digital_Signature_Algorithm .. _`public-key`: https://en.wikipedia.org/wiki/Public-key_cryptography .. _`FIPS 186-4`: http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf - +.. _`at least 2048`: http://www.ecrypt.eu.org/documents/D.SPA.20.pdf @@ -2,6 +2,7 @@ addopts = -r s markers = cipher: this test requires a backend providing CipherBackend + dsa: this test requires a backend providing DSABackend hash: this test requires a backend providing HashBackend hmac: this test requires a backend providing HMACBackend pbkdf2hmac: this test requires a backend providing PBKDF2HMACBackend diff --git a/tests/conftest.py b/tests/conftest.py index 8e89af57..1ee2a993 100644 --- a/tests/conftest.py +++ b/tests/conftest.py @@ -17,7 +17,8 @@ import pytest from cryptography.hazmat.backends import _available_backends from cryptography.hazmat.backends.interfaces import ( - CipherBackend, HMACBackend, HashBackend, PBKDF2HMACBackend, RSABackend + CipherBackend, DSABackend, HMACBackend, HashBackend, PBKDF2HMACBackend, + RSABackend ) from .utils import check_backend_support, check_for_iface, select_backends @@ -37,6 +38,7 @@ def pytest_runtest_setup(item): check_for_iface("cipher", CipherBackend, item) check_for_iface("hash", HashBackend, item) check_for_iface("pbkdf2hmac", PBKDF2HMACBackend, item) + check_for_iface("dsa", DSABackend, item) check_for_iface("rsa", RSABackend, item) check_backend_support(item) diff --git a/tests/hazmat/backends/test_multibackend.py b/tests/hazmat/backends/test_multibackend.py index f0be72b2..f46009d4 100644 --- a/tests/hazmat/backends/test_multibackend.py +++ b/tests/hazmat/backends/test_multibackend.py @@ -18,7 +18,8 @@ from cryptography.exceptions import ( UnsupportedAlgorithm, _Reasons ) from cryptography.hazmat.backends.interfaces import ( - CipherBackend, HMACBackend, HashBackend, PBKDF2HMACBackend, RSABackend + CipherBackend, DSABackend, HMACBackend, HashBackend, PBKDF2HMACBackend, + RSABackend ) from cryptography.hazmat.backends.multibackend import MultiBackend from cryptography.hazmat.primitives import hashes, hmac @@ -98,6 +99,15 @@ class DummyRSABackend(object): pass +@utils.register_interface(DSABackend) +class DummyDSABackend(object): + def generate_dsa_parameters(self, key_size): + pass + + def generate_dsa_private_key(self, parameters): + pass + + class TestMultiBackend(object): def test_ciphers(self): backend = MultiBackend([ @@ -193,3 +203,24 @@ class TestMultiBackend(object): ): backend.create_rsa_verification_ctx( "public_key", "sig", padding.PKCS1v15(), hashes.MD5()) + + def test_dsa(self): + backend = MultiBackend([ + DummyDSABackend() + ]) + + backend.generate_dsa_parameters(key_size=1024) + + parameters = object() + backend.generate_dsa_private_key(parameters) + + backend = MultiBackend([]) + with raises_unsupported_algorithm( + _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM + ): + backend.generate_dsa_parameters(key_size=1024) + + with raises_unsupported_algorithm( + _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM + ): + backend.generate_dsa_private_key(parameters) diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py index 016da0fc..6ab16627 100644 --- a/tests/hazmat/backends/test_openssl.py +++ b/tests/hazmat/backends/test_openssl.py @@ -21,13 +21,15 @@ from cryptography.exceptions import ( ) from cryptography.hazmat.backends.openssl.backend import Backend, backend from cryptography.hazmat.primitives import hashes, interfaces -from cryptography.hazmat.primitives.asymmetric import padding, rsa +from cryptography.hazmat.primitives.asymmetric import dsa, padding, rsa from cryptography.hazmat.primitives.ciphers import Cipher from cryptography.hazmat.primitives.ciphers.algorithms import AES from cryptography.hazmat.primitives.ciphers.modes import CBC from ...utils import raises_unsupported_algorithm +from cryptography.utils import bit_length + @utils.register_interface(interfaces.Mode) class DummyMode(object): @@ -192,6 +194,27 @@ class TestOpenSSL(object): res = backend._lib.ENGINE_free(e) assert res == 1 + @pytest.mark.skipif( + backend._lib.OPENSSL_VERSION_NUMBER >= 0x1000000f, + reason="Requires an older OpenSSL. Must be < 1.0.0" + ) + def test_large_key_size_on_old_openssl(self): + with pytest.raises(ValueError): + dsa.DSAParameters.generate(2048, backend=backend) + + with pytest.raises(ValueError): + dsa.DSAParameters.generate(3072, backend=backend) + + @pytest.mark.skipif( + backend._lib.OPENSSL_VERSION_NUMBER < 0x1000000f, + reason="Requires a newer OpenSSL. Must be >= 1.0.0" + ) + def test_large_key_size_on_new_openssl(self): + parameters = dsa.DSAParameters.generate(2048, backend) + assert bit_length(parameters.p) == 2048 + parameters = dsa.DSAParameters.generate(3072, backend) + assert bit_length(parameters.p) == 3072 + class TestOpenSSLRandomEngine(object): def teardown_method(self, method): diff --git a/tests/hazmat/primitives/test_dsa.py b/tests/hazmat/primitives/test_dsa.py index 2a2b9bda..2b5d4bb3 100644 --- a/tests/hazmat/primitives/test_dsa.py +++ b/tests/hazmat/primitives/test_dsa.py @@ -14,9 +14,18 @@ from __future__ import absolute_import, division, print_function +import os + import pytest +from cryptography.exceptions import _Reasons from cryptography.hazmat.primitives.asymmetric import dsa +from cryptography.utils import bit_length + +from ...utils import ( + load_vectors_from_file, load_fips_dsa_key_pair_vectors, + raises_unsupported_algorithm +) def _check_dsa_private_key(skey): @@ -53,6 +62,7 @@ def _check_dsa_private_key(skey): assert skey_parameters.generator == pkey_parameters.generator +@pytest.mark.dsa class TestDSA(object): _parameters_1024 = { 'p': 'd38311e2cd388c3ed698e82fdf88eb92b5a9a483dc88005d4b725ef341eabb47' @@ -157,6 +167,35 @@ class TestDSA(object): 'f90f7dff6d2bae' } + def test_generate_dsa_parameters(self, backend): + parameters = dsa.DSAParameters.generate(1024, backend) + assert bit_length(parameters.p) == 1024 + + def test_generate_invalid_dsa_parameters(self, backend): + with pytest.raises(ValueError): + dsa.DSAParameters.generate(1, backend) + + @pytest.mark.parametrize( + "vector", + load_vectors_from_file( + os.path.join( + "asymmetric", "DSA", "FIPS_186-3", "KeyPair.rsp"), + load_fips_dsa_key_pair_vectors + ) + ) + def test_generate_dsa_keys(self, vector, backend): + parameters = dsa.DSAParameters(modulus=vector['p'], + subgroup_order=vector['q'], + generator=vector['g']) + skey = dsa.DSAPrivateKey.generate(parameters, backend) + + skey_parameters = skey.parameters() + assert skey_parameters.p == vector['p'] + assert skey_parameters.q == vector['q'] + assert skey_parameters.g == vector['g'] + assert skey.key_size == bit_length(vector['p']) + assert skey.y == pow(skey_parameters.g, skey.x, skey_parameters.p) + def test_invalid_parameters_argument_types(self): with pytest.raises(TypeError): dsa.DSAParameters(None, None, None) @@ -679,3 +718,14 @@ class TestDSA(object): generator=int(self._parameters_1024['g'], 16), y=None ) + + +def test_dsa_generate_invalid_backend(): + pretend_backend = object() + + with raises_unsupported_algorithm(_Reasons.BACKEND_MISSING_INTERFACE): + dsa.DSAParameters.generate(1024, pretend_backend) + + pretend_parameters = object() + with raises_unsupported_algorithm(_Reasons.BACKEND_MISSING_INTERFACE): + dsa.DSAPrivateKey.generate(pretend_parameters, pretend_backend) |