path: root/tests/hazmat/primitives/test_dh.py

# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

from __future__ import absolute_import, division, print_function

import binascii
import itertools
import os

import pytest

from cryptography.hazmat.backends.interfaces import (
    DERSerializationBackend, DHBackend, PEMSerializationBackend)
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import dh
from cryptography.utils import int_from_bytes

from ...doubles import DummyKeySerializationEncryption
from ...utils import load_nist_vectors, load_vectors_from_file


def _skip_dhx_unsupported(backend, is_dhx):
    if not is_dhx:
        return
    if not backend.dh_x942_serialization_supported():
        pytest.skip(
            "DH x9.42 serialization is not supported"
        )


def test_dh_parameternumbers():
    params = dh.DHParameterNumbers(
        65537, 2
    )

    assert params.p == 65537
    assert params.g == 2

    with pytest.raises(TypeError):
        dh.DHParameterNumbers(
            None, 2
        )

    with pytest.raises(TypeError):
        dh.DHParameterNumbers(
            65537, None
        )

    with pytest.raises(TypeError):
        dh.DHParameterNumbers(
            None, None
        )

    with pytest.raises(ValueError):
        dh.DHParameterNumbers(
            65537, 1
        )

    params = dh.DHParameterNumbers(
        65537, 7, 1245
    )

    assert params.p == 65537
    assert params.g == 7
    assert params.q == 1245

    with pytest.raises(TypeError):
        dh.DHParameterNumbers(
            65537, 2, "hello"
        )


def test_dh_numbers():
    params = dh.DHParameterNumbers(
        65537, 2
    )

    public = dh.DHPublicNumbers(
        1, params
    )

    assert public.parameter_numbers is params
    assert public.y == 1

    with pytest.raises(TypeError):
        dh.DHPublicNumbers(
            1, None
        )

    with pytest.raises(TypeError):
        dh.DHPublicNumbers(
            None, params
        )

    private = dh.DHPrivateNumbers(
        1, public
    )

    assert private.public_numbers is public
    assert private.x == 1

    with pytest.raises(TypeError):
        dh.DHPrivateNumbers(
            1, None
        )

    with pytest.raises(TypeError):
        dh.DHPrivateNumbers(
            None, public
        )


def test_dh_parameter_numbers_equality():
    assert dh.DHParameterNumbers(65537, 2) == dh.DHParameterNumbers(65537, 2)
    assert dh.DHParameterNumbers(65537, 7, 12345) == dh.DHParameterNumbers(
        65537, 7, 12345)
    assert dh.DHParameterNumbers(6, 2) != dh.DHParameterNumbers(65537, 2)
    assert dh.DHParameterNumbers(65537, 2, 123) != dh.DHParameterNumbers(
        65537, 2, 456)
    assert dh.DHParameterNumbers(65537, 5) != dh.DHParameterNumbers(65537, 2)
    assert dh.DHParameterNumbers(65537, 2) != object()


def test_dh_private_numbers_equality():
    params = dh.DHParameterNumbers(65537, 2)
    public = dh.DHPublicNumbers(1, params)
    private = dh.DHPrivateNumbers(2, public)

    assert private == dh.DHPrivateNumbers(2, public)
    assert private != dh.DHPrivateNumbers(0, public)
    assert private != dh.DHPrivateNumbers(2, dh.DHPublicNumbers(0, params))
    assert private != dh.DHPrivateNumbers(
        2, dh.DHPublicNumbers(1, dh.DHParameterNumbers(65537, 5))
    )
    assert private != object()


def test_dh_public_numbers_equality():
    params = dh.DHParameterNumbers(65537, 2)
    public = dh.DHPublicNumbers(1, params)

    assert public == dh.DHPublicNumbers(1, params)
    assert public != dh.DHPublicNumbers(0, params)
    assert public != dh.DHPublicNumbers(1, dh.DHParameterNumbers(65537, 5))
    assert public != object()


@pytest.mark.requires_backend_interface(interface=DHBackend)
class TestDH(object):
    def test_small_key_generate_dh(self, backend):
        with pytest.raises(ValueError):
            dh.generate_parameters(2, 511, backend)

    def test_unsupported_generator_generate_dh(self, backend):
        with pytest.raises(ValueError):
            dh.generate_parameters(7, 512, backend)

    def test_dh_parameters_supported(self, backend):
        valid_p = int(
            b"907c7211ae61aaaba1825ff53b6cb71ac6df9f1a424c033f4a0a41ac42fad3a9"
            b"bcfc7f938a269710ed69e330523e4039029b7900977c740990d46efed79b9bbe"
            b"73505ae878808944ce4d9c6c52daecc0a87dc889c53499be93db8551ee685f30"
            b"349bf1b443d4ebaee0d5e8b441a40d4e8178f8f612f657a5eb91e0a8e"
            b"107755f", 16
        )
        assert backend.dh_parameters_supported(valid_p, 5)
        assert not backend.dh_parameters_supported(23, 22)

    @pytest.mark.parametrize(
        "vector",
        load_vectors_from_file(
            os.path.join("asymmetric", "DH", "rfc3526.txt"),
            load_nist_vectors
        )
    )
    def test_dh_parameters_allows_rfc3526_groups(self, backend, vector):
        p = int_from_bytes(binascii.unhexlify(vector["p"]), 'big')
        params = dh.DHParameterNumbers(p, int(vector["g"]))
        param = params.parameters(backend)
        key = param.generate_private_key()
        # This confirms that a key generated with this group
        # will pass DH_check when we serialize and de-serialize it via
        # the Numbers path.
        roundtripped_key = key.private_numbers().private_key(backend)
        assert key.private_numbers() == roundtripped_key.private_numbers()

    @pytest.mark.parametrize(
        "vector",
        load_vectors_from_file(
            os.path.join("asymmetric", "DH", "RFC5114.txt"),
            load_nist_vectors))
    def test_dh_parameters_supported_with_q(self, backend, vector):
        assert backend.dh_parameters_supported(int(vector["p"], 16),
                                               int(vector["g"], 16),
                                               int(vector["q"], 16))

    @pytest.mark.parametrize("with_q", [False, True])
    def test_convert_to_numbers(self, backend, with_q):
        if with_q:
            vector = load_vectors_from_file(
                os.path.join("asymmetric", "DH", "RFC5114.txt"),
                load_nist_vectors)[0]
            p = int(vector["p"], 16)
            g = int(vector["g"], 16)
            q = int(vector["q"], 16)
        else:
            parameters = backend.generate_dh_private_key_and_parameters(2, 512)

            private = parameters.private_numbers()

            p = private.public_numbers.parameter_numbers.p
            g = private.public_numbers.parameter_numbers.g
            q = None

        params = dh.DHParameterNumbers(p, g, q)
        public = dh.DHPublicNumbers(1, params)
        private = dh.DHPrivateNumbers(2, public)

        deserialized_params = params.parameters(backend)
        deserialized_public = public.public_key(backend)
        deserialized_private = private.private_key(backend)

        assert isinstance(deserialized_params,
                          dh.DHParametersWithSerialization)
        assert isinstance(deserialized_public,
                          dh.DHPublicKeyWithSerialization)
        assert isinstance(deserialized_private,
                          dh.DHPrivateKeyWithSerialization)

    def test_numbers_unsupported_parameters(self, backend):
        # p is set to 21 because when calling private_key we want it to
        # fail the DH_check call OpenSSL does. Originally this was 23, but
        # we are allowing p % 24 to == 23 with this PR (see #3768 for more)
        # By setting it to 21 it fails later in DH_check in a primality check
        # which triggers the code path we want to test
        params = dh.DHParameterNumbers(21, 2)
        public = dh.DHPublicNumbers(1, params)
        private = dh.DHPrivateNumbers(2, public)

        with pytest.raises(ValueError):
            private.private_key(backend)

    @pytest.mark.parametrize("with_q", [False, True])
    def test_generate_dh(self, backend, with_q):
        if with_q:
            vector = load_vectors_from_file(
                os.path.join("asymmetric", "DH", "RFC5114.txt"),
                load_nist_vectors)[0]
            p = int(vector["p"], 16)
            g = int(vector["g"], 16)
            q = int(vector["q"], 16)
            parameters = dh.DHParameterNumbers(p, g, q).parameters(backend)
            key_size = 1024
        else:
            generator = 2
            key_size = 512

            parameters = dh.generate_parameters(generator, key_size, backend)
        assert isinstance(parameters, dh.DHParameters)

        key = parameters.generate_private_key()
        assert isinstance(key, dh.DHPrivateKey)
        assert key.key_size == key_size

        public = key.public_key()
        assert isinstance(public, dh.DHPublicKey)
        assert public.key_size == key_size

        assert isinstance(parameters, dh.DHParametersWithSerialization)
        parameter_numbers = parameters.parameter_numbers()
        assert isinstance(parameter_numbers, dh.DHParameterNumbers)
        assert parameter_numbers.p.bit_length() == key_size

        assert isinstance(public, dh.DHPublicKeyWithSerialization)
        assert isinstance(public.public_numbers(), dh.DHPublicNumbers)
        assert isinstance(public.parameters(), dh.DHParameters)

        assert isinstance(key, dh.DHPrivateKeyWithSerialization)
        assert isinstance(key.private_numbers(), dh.DHPrivateNumbers)
        assert isinstance(key.parameters(), dh.DHParameters)

    def test_exchange(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        assert isinstance(parameters, dh.DHParameters)

        key1 = parameters.generate_private_key()
        key2 = parameters.generate_private_key()

        symkey1 = key1.exchange(key2.public_key())
        assert symkey1
        assert len(symkey1) == 512 // 8

        symkey2 = key2.exchange(key1.public_key())
        assert symkey1 == symkey2

    def test_exchange_algorithm(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)

        key1 = parameters.generate_private_key()
        key2 = parameters.generate_private_key()

        shared_key_bytes = key2.exchange(key1.public_key())
        symkey = int_from_bytes(shared_key_bytes, 'big')

        symkey_manual = pow(key1.public_key().public_numbers().y,
                            key2.private_numbers().x,
                            parameters.parameter_numbers().p)

        assert symkey == symkey_manual

    def test_symmetric_key_padding(self, backend):
        """
        This test has specific parameters that produce a symmetric key
        In length 63 bytes instead 64. We make sure here that we add
        padding to the key.
        """
        p = int("11859949538425015739337467917303613431031019140213666"
                "129025407300654026585086345323066284800963463204246390"
                "256567934582260424238844463330887962689642467123")
        g = 2
        y = int("32155788395534640648739966373159697798396966919821525"
                "72238852825117261342483718574508213761865276905503199"
                "969908098203345481366464874759377454476688391248")
        x = int("409364065449673443397833358558926598469347813468816037"
                "268451847116982490733450463194921405069999008617231539"
                "7147035896687401350877308899732826446337707128")
        parameters = dh.DHParameterNumbers(p, g)
        public = dh.DHPublicNumbers(y, parameters)
        private = dh.DHPrivateNumbers(x, public)
        key = private.private_key(backend)
        symkey = key.exchange(public.public_key(backend))
        assert len(symkey) == 512 // 8
        assert symkey[:1] == b'\x00'

    @pytest.mark.parametrize(
        "vector",
        load_vectors_from_file(
            os.path.join("asymmetric", "DH", "bad_exchange.txt"),
            load_nist_vectors))
    def test_bad_exchange(self, backend, vector):
        parameters1 = dh.DHParameterNumbers(int(vector["p1"]),
                                            int(vector["g"]))
        public1 = dh.DHPublicNumbers(int(vector["y1"]), parameters1)
        private1 = dh.DHPrivateNumbers(int(vector["x1"]), public1)
        key1 = private1.private_key(backend)
        pub_key1 = key1.public_key()

        parameters2 = dh.DHParameterNumbers(int(vector["p2"]),
                                            int(vector["g"]))
        public2 = dh.DHPublicNumbers(int(vector["y2"]), parameters2)
        private2 = dh.DHPrivateNumbers(int(vector["x2"]), public2)
        key2 = private2.private_key(backend)
        pub_key2 = key2.public_key()

        if pub_key2.public_numbers().y >= parameters1.p:
            with pytest.raises(ValueError):
                key1.exchange(pub_key2)
        else:
            symkey1 = key1.exchange(pub_key2)
            assert symkey1

            symkey2 = key2.exchange(pub_key1)

            assert symkey1 != symkey2

    @pytest.mark.parametrize(
        "vector",
        load_vectors_from_file(
            os.path.join("asymmetric", "DH", "vec.txt"),
            load_nist_vectors))
    def test_dh_vectors(self, backend, vector):
        parameters = dh.DHParameterNumbers(int(vector["p"]),
                                           int(vector["g"]))
        public = dh.DHPublicNumbers(int(vector["y"]), parameters)
        private = dh.DHPrivateNumbers(int(vector["x"]), public)
        key = private.private_key(backend)
        symkey = key.exchange(public.public_key(backend))

        assert int_from_bytes(symkey, 'big') == int(vector["k"], 16)

    @pytest.mark.parametrize(
        "vector",
        load_vectors_from_file(
            os.path.join("asymmetric", "DH", "RFC5114.txt"),
            load_nist_vectors))
    def test_dh_vectors_with_q(self, backend, vector):
        parameters = dh.DHParameterNumbers(int(vector["p"], 16),
                                           int(vector["g"], 16),
                                           int(vector["q"], 16))
        public1 = dh.DHPublicNumbers(int(vector["ystatcavs"], 16), parameters)
        private1 = dh.DHPrivateNumbers(int(vector["xstatcavs"], 16), public1)
        public2 = dh.DHPublicNumbers(int(vector["ystatiut"], 16), parameters)
        private2 = dh.DHPrivateNumbers(int(vector["xstatiut"], 16), public2)
        key1 = private1.private_key(backend)
        key2 = private2.private_key(backend)
        symkey1 = key1.exchange(public2.public_key(backend))
        symkey2 = key2.exchange(public1.public_key(backend))

        assert int_from_bytes(symkey1, 'big') == int(vector["z"], 16)
        assert int_from_bytes(symkey2, 'big') == int(vector["z"], 16)


@pytest.mark.requires_backend_interface(interface=DHBackend)
@pytest.mark.requires_backend_interface(interface=PEMSerializationBackend)
@pytest.mark.requires_backend_interface(interface=DERSerializationBackend)
class TestDHPrivateKeySerialization(object):

    @pytest.mark.parametrize(
        ("encoding", "loader_func"),
        [
            [
                serialization.Encoding.PEM,
                serialization.load_pem_private_key
            ],
            [
                serialization.Encoding.DER,
                serialization.load_der_private_key
            ],
        ]
    )
    def test_private_bytes_unencrypted(self, backend, encoding,
                                       loader_func):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        serialized = key.private_bytes(
            encoding, serialization.PrivateFormat.PKCS8,
            serialization.NoEncryption()
        )
        loaded_key = loader_func(serialized, None, backend)
        loaded_priv_num = loaded_key.private_numbers()
        priv_num = key.private_numbers()
        assert loaded_priv_num == priv_num

    @pytest.mark.parametrize(
        ("encoding", "fmt"),
        [
            (serialization.Encoding.Raw, serialization.PrivateFormat.PKCS8),
            (serialization.Encoding.DER, serialization.PrivateFormat.Raw),
            (serialization.Encoding.Raw, serialization.PrivateFormat.Raw),
            (serialization.Encoding.X962, serialization.PrivateFormat.PKCS8),
        ]
    )
    def test_private_bytes_rejects_invalid(self, encoding, fmt, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        with pytest.raises(ValueError):
            key.private_bytes(encoding, fmt, serialization.NoEncryption())

    @pytest.mark.parametrize(
        ("key_path", "loader_func", "encoding", "is_dhx"),
        [
            (
                os.path.join("asymmetric", "DH", "dhkey.pem"),
                serialization.load_pem_private_key,
                serialization.Encoding.PEM,
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhkey.der"),
                serialization.load_der_private_key,
                serialization.Encoding.DER,
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.pem"),
                serialization.load_pem_private_key,
                serialization.Encoding.PEM,
                True,
            ), (
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.der"),
                serialization.load_der_private_key,
                serialization.Encoding.DER,
                True,
            )
        ]
    )
    def test_private_bytes_match(self, key_path, loader_func,
                                 encoding, is_dhx, backend):
        _skip_dhx_unsupported(backend, is_dhx)
        key_bytes = load_vectors_from_file(
            key_path,
            lambda pemfile: pemfile.read(), mode="rb"
        )
        key = loader_func(key_bytes, None, backend)
        serialized = key.private_bytes(
            encoding, serialization.PrivateFormat.PKCS8,
            serialization.NoEncryption()
        )
        assert serialized == key_bytes

    @pytest.mark.parametrize(
        ("key_path", "loader_func", "vec_path", "is_dhx"),
        [
            (
                os.path.join("asymmetric", "DH", "dhkey.pem"),
                serialization.load_pem_private_key,
                os.path.join("asymmetric", "DH", "dhkey.txt"),
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhkey.der"),
                serialization.load_der_private_key,
                os.path.join("asymmetric", "DH", "dhkey.txt"),
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.pem"),
                serialization.load_pem_private_key,
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.txt"),
                True,
            ), (
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.der"),
                serialization.load_der_private_key,
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.txt"),
                True,
            )
        ]
    )
    def test_private_bytes_values(self, key_path, loader_func,
                                  vec_path, is_dhx, backend):
        _skip_dhx_unsupported(backend, is_dhx)
        key_bytes = load_vectors_from_file(
            key_path,
            lambda pemfile: pemfile.read(), mode="rb"
        )
        vec = load_vectors_from_file(vec_path, load_nist_vectors)[0]
        key = loader_func(key_bytes, None, backend)
        private_numbers = key.private_numbers()
        assert private_numbers.x == int(vec["x"], 16)
        assert private_numbers.public_numbers.y == int(vec["y"], 16)
        assert private_numbers.public_numbers.parameter_numbers.g == int(
            vec["g"], 16)
        assert private_numbers.public_numbers.parameter_numbers.p == int(
            vec["p"], 16)
        if "q" in vec:
            assert private_numbers.public_numbers.parameter_numbers.q == int(
                vec["q"], 16)
        else:
            assert private_numbers.public_numbers.parameter_numbers.q is None

    def test_private_bytes_traditional_openssl_invalid(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        with pytest.raises(ValueError):
            key.private_bytes(
                serialization.Encoding.PEM,
                serialization.PrivateFormat.TraditionalOpenSSL,
                serialization.NoEncryption()
            )

    def test_private_bytes_invalid_encoding(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        with pytest.raises(TypeError):
            key.private_bytes(
                "notencoding",
                serialization.PrivateFormat.PKCS8,
                serialization.NoEncryption()
            )

    def test_private_bytes_invalid_format(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        with pytest.raises(ValueError):
            key.private_bytes(
                serialization.Encoding.PEM,
                "invalidformat",
                serialization.NoEncryption()
            )

    def test_private_bytes_invalid_encryption_algorithm(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        with pytest.raises(TypeError):
            key.private_bytes(
                serialization.Encoding.PEM,
                serialization.PrivateFormat.PKCS8,
                "notanencalg"
            )

    def test_private_bytes_unsupported_encryption_type(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key()
        with pytest.raises(ValueError):
            key.private_bytes(
                serialization.Encoding.PEM,
                serialization.PrivateFormat.PKCS8,
                DummyKeySerializationEncryption()
            )


@pytest.mark.requires_backend_interface(interface=DHBackend)
@pytest.mark.requires_backend_interface(interface=PEMSerializationBackend)
@pytest.mark.requires_backend_interface(interface=DERSerializationBackend)
class TestDHPublicKeySerialization(object):

    @pytest.mark.parametrize(
        ("encoding", "loader_func"),
        [
            [
                serialization.Encoding.PEM,
                serialization.load_pem_public_key
            ],
            [
                serialization.Encoding.DER,
                serialization.load_der_public_key
            ],
        ]
    )
    def test_public_bytes(self, backend, encoding,
                          loader_func):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key().public_key()
        serialized = key.public_bytes(
            encoding, serialization.PublicFormat.SubjectPublicKeyInfo
        )
        loaded_key = loader_func(serialized, backend)
        loaded_pub_num = loaded_key.public_numbers()
        pub_num = key.public_numbers()
        assert loaded_pub_num == pub_num

    @pytest.mark.parametrize(
        ("key_path", "loader_func", "encoding", "is_dhx"),
        [
            (
                os.path.join("asymmetric", "DH", "dhpub.pem"),
                serialization.load_pem_public_key,
                serialization.Encoding.PEM,
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhpub.der"),
                serialization.load_der_public_key,
                serialization.Encoding.DER,
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhpub_rfc5114_2.pem"),
                serialization.load_pem_public_key,
                serialization.Encoding.PEM,
                True,
            ), (
                os.path.join("asymmetric", "DH", "dhpub_rfc5114_2.der"),
                serialization.load_der_public_key,
                serialization.Encoding.DER,
                True,
            )
        ]
    )
    def test_public_bytes_match(self, key_path, loader_func,
                                encoding, is_dhx, backend):
        _skip_dhx_unsupported(backend, is_dhx)
        key_bytes = load_vectors_from_file(
            key_path,
            lambda pemfile: pemfile.read(), mode="rb"
        )
        pub_key = loader_func(key_bytes, backend)
        serialized = pub_key.public_bytes(
            encoding,
            serialization.PublicFormat.SubjectPublicKeyInfo,
        )
        assert serialized == key_bytes

    @pytest.mark.parametrize(
        ("key_path", "loader_func", "vec_path", "is_dhx"),
        [
            (
                os.path.join("asymmetric", "DH", "dhpub.pem"),
                serialization.load_pem_public_key,
                os.path.join("asymmetric", "DH", "dhkey.txt"),
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhpub.der"),
                serialization.load_der_public_key,
                os.path.join("asymmetric", "DH", "dhkey.txt"),
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhpub_rfc5114_2.pem"),
                serialization.load_pem_public_key,
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.txt"),
                True,
            ), (
                os.path.join("asymmetric", "DH", "dhpub_rfc5114_2.der"),
                serialization.load_der_public_key,
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.txt"),
                True,
            )
        ]
    )
    def test_public_bytes_values(self, key_path, loader_func,
                                 vec_path, is_dhx, backend):
        _skip_dhx_unsupported(backend, is_dhx)
        key_bytes = load_vectors_from_file(
            key_path,
            lambda pemfile: pemfile.read(), mode="rb"
        )
        vec = load_vectors_from_file(vec_path, load_nist_vectors)[0]
        pub_key = loader_func(key_bytes, backend)
        public_numbers = pub_key.public_numbers()
        assert public_numbers.y == int(vec["y"], 16)
        assert public_numbers.parameter_numbers.g == int(vec["g"], 16)
        assert public_numbers.parameter_numbers.p == int(vec["p"], 16)
        if "q" in vec:
            assert public_numbers.parameter_numbers.q == int(vec["q"], 16)
        else:
            assert public_numbers.parameter_numbers.q is None

    def test_public_bytes_invalid_encoding(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key().public_key()
        with pytest.raises(TypeError):
            key.public_bytes(
                "notencoding",
                serialization.PublicFormat.SubjectPublicKeyInfo
            )

    def test_public_bytes_pkcs1_unsupported(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key().public_key()
        with pytest.raises(ValueError):
            key.public_bytes(
                serialization.Encoding.PEM, serialization.PublicFormat.PKCS1
            )


@pytest.mark.requires_backend_interface(interface=DHBackend)
@pytest.mark.requires_backend_interface(interface=PEMSerializationBackend)
@pytest.mark.requires_backend_interface(interface=DERSerializationBackend)
class TestDHParameterSerialization(object):

    @pytest.mark.parametrize(
        ("encoding", "loader_func"),
        [
            [
                serialization.Encoding.PEM,
                serialization.load_pem_parameters
            ],
            [
                serialization.Encoding.DER,
                serialization.load_der_parameters
            ],
        ]
    )
    def test_parameter_bytes(self, backend, encoding,
                             loader_func):
        parameters = dh.generate_parameters(2, 512, backend)
        serialized = parameters.parameter_bytes(
            encoding, serialization.ParameterFormat.PKCS3
        )
        loaded_key = loader_func(serialized, backend)
        loaded_param_num = loaded_key.parameter_numbers()
        assert loaded_param_num == parameters.parameter_numbers()

    @pytest.mark.parametrize(
        ("param_path", "loader_func", "encoding", "is_dhx"),
        [
            (
                os.path.join("asymmetric", "DH", "dhp.pem"),
                serialization.load_pem_parameters,
                serialization.Encoding.PEM,
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhp.der"),
                serialization.load_der_parameters,
                serialization.Encoding.DER,
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhp_rfc5114_2.pem"),
                serialization.load_pem_parameters,
                serialization.Encoding.PEM,
                True,
            ), (
                os.path.join("asymmetric", "DH", "dhp_rfc5114_2.der"),
                serialization.load_der_parameters,
                serialization.Encoding.DER,
                True,
            )
        ]
    )
    def test_parameter_bytes_match(self, param_path, loader_func,
                                   encoding, backend, is_dhx):
        _skip_dhx_unsupported(backend, is_dhx)
        param_bytes = load_vectors_from_file(
            param_path,
            lambda pemfile: pemfile.read(), mode="rb"
        )
        parameters = loader_func(param_bytes, backend)
        serialized = parameters.parameter_bytes(
            encoding,
            serialization.ParameterFormat.PKCS3,
        )
        assert serialized == param_bytes

    @pytest.mark.parametrize(
        ("param_path", "loader_func", "vec_path", "is_dhx"),
        [
            (
                os.path.join("asymmetric", "DH", "dhp.pem"),
                serialization.load_pem_parameters,
                os.path.join("asymmetric", "DH", "dhkey.txt"),
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhp.der"),
                serialization.load_der_parameters,
                os.path.join("asymmetric", "DH", "dhkey.txt"),
                False,
            ), (
                os.path.join("asymmetric", "DH", "dhp_rfc5114_2.pem"),
                serialization.load_pem_parameters,
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.txt"),
                True,
            ), (
                os.path.join("asymmetric", "DH", "dhp_rfc5114_2.der"),
                serialization.load_der_parameters,
                os.path.join("asymmetric", "DH", "dhkey_rfc5114_2.txt"),
                True,
            )
        ]
    )
    def test_public_bytes_values(self, param_path, loader_func,
                                 vec_path, backend, is_dhx):
        _skip_dhx_unsupported(backend, is_dhx)
        key_bytes = load_vectors_from_file(
            param_path,
            lambda pemfile: pemfile.read(), mode="rb"
        )
        vec = load_vectors_from_file(vec_path, load_nist_vectors)[0]
        parameters = loader_func(key_bytes, backend)
        parameter_numbers = parameters.parameter_numbers()
        assert parameter_numbers.g == int(vec["g"], 16)
        assert parameter_numbers.p == int(vec["p"], 16)
        if "q" in vec:
            assert parameter_numbers.q == int(vec["q"], 16)
        else:
            assert parameter_numbers.q is None

    @pytest.mark.parametrize(
        ("encoding", "fmt"),
        [
            (
                serialization.Encoding.Raw,
                serialization.PublicFormat.SubjectPublicKeyInfo
            ),
            (serialization.Encoding.Raw, serialization.PublicFormat.PKCS1),
        ] + list(itertools.product(
            [
                serialization.Encoding.Raw,
                serialization.Encoding.X962,
                serialization.Encoding.PEM,
                serialization.Encoding.DER
            ],
            [
                serialization.PublicFormat.Raw,
                serialization.PublicFormat.UncompressedPoint,
                serialization.PublicFormat.CompressedPoint
            ]
        ))
    )
    def test_public_bytes_rejects_invalid(self, encoding, fmt, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        key = parameters.generate_private_key().public_key()
        with pytest.raises(ValueError):
            key.public_bytes(encoding, fmt)

    def test_parameter_bytes_invalid_encoding(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        with pytest.raises(TypeError):
            parameters.parameter_bytes(
                "notencoding",
                serialization.ParameterFormat.PKCS3
            )

    def test_parameter_bytes_invalid_format(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        with pytest.raises(ValueError):
            parameters.parameter_bytes(
                serialization.Encoding.PEM,
                "notformat"
            )

    def test_parameter_bytes_openssh_unsupported(self, backend):
        parameters = dh.generate_parameters(2, 512, backend)
        with pytest.raises(TypeError):
            parameters.parameter_bytes(
                serialization.Encoding.OpenSSH,
                serialization.ParameterFormat.PKCS3
            )