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# 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.
import abc
import typing
from cryptography import utils
from cryptography.hazmat.backends import _get_backend
from cryptography.hazmat.primitives import serialization
_MIN_MODULUS_SIZE = 512
def generate_parameters(generator, key_size, backend=None) -> "DHParameters":
backend = _get_backend(backend)
return backend.generate_dh_parameters(generator, key_size)
class DHParameterNumbers(object):
def __init__(self, p: int, g: int, q: typing.Optional[int] = None):
if not isinstance(p, int) or not isinstance(g, int):
raise TypeError("p and g must be integers")
if q is not None and not isinstance(q, int):
raise TypeError("q must be integer or None")
if g < 2:
raise ValueError("DH generator must be 2 or greater")
if p.bit_length() < _MIN_MODULUS_SIZE:
raise ValueError(
"p (modulus) must be at least {}-bit".format(_MIN_MODULUS_SIZE)
)
self._p = p
self._g = g
self._q = q
def __eq__(self, other):
if not isinstance(other, DHParameterNumbers):
return NotImplemented
return (
self._p == other._p and self._g == other._g and self._q == other._q
)
def __ne__(self, other):
return not self == other
def parameters(self, backend=None):
backend = _get_backend(backend)
return backend.load_dh_parameter_numbers(self)
p = utils.read_only_property("_p")
g = utils.read_only_property("_g")
q = utils.read_only_property("_q")
class DHPublicNumbers(object):
def __init__(self, y, parameter_numbers: DHParameterNumbers):
if not isinstance(y, int):
raise TypeError("y must be an integer.")
if not isinstance(parameter_numbers, DHParameterNumbers):
raise TypeError(
"parameters must be an instance of DHParameterNumbers."
)
self._y = y
self._parameter_numbers = parameter_numbers
def __eq__(self, other):
if not isinstance(other, DHPublicNumbers):
return NotImplemented
return (
self._y == other._y
and self._parameter_numbers == other._parameter_numbers
)
def __ne__(self, other):
return not self == other
def public_key(self, backend=None) -> "DHPublicKey":
backend = _get_backend(backend)
return backend.load_dh_public_numbers(self)
y = utils.read_only_property("_y")
parameter_numbers = utils.read_only_property("_parameter_numbers")
class DHPrivateNumbers(object):
def __init__(self, x, public_numbers: DHPublicNumbers):
if not isinstance(x, int):
raise TypeError("x must be an integer.")
if not isinstance(public_numbers, DHPublicNumbers):
raise TypeError(
"public_numbers must be an instance of " "DHPublicNumbers."
)
self._x = x
self._public_numbers = public_numbers
def __eq__(self, other):
if not isinstance(other, DHPrivateNumbers):
return NotImplemented
return (
self._x == other._x
and self._public_numbers == other._public_numbers
)
def __ne__(self, other):
return not self == other
def private_key(self, backend=None) -> "DHPrivateKey":
backend = _get_backend(backend)
return backend.load_dh_private_numbers(self)
public_numbers = utils.read_only_property("_public_numbers")
x = utils.read_only_property("_x")
class DHParameters(metaclass=abc.ABCMeta):
@abc.abstractmethod
def generate_private_key(self) -> "DHPrivateKey":
"""
Generates and returns a DHPrivateKey.
"""
@abc.abstractmethod
def parameter_bytes(
self,
encoding: "serialization.Encoding",
format: "serialization.ParameterFormat",
) -> bytes:
"""
Returns the parameters serialized as bytes.
"""
@abc.abstractmethod
def parameter_numbers(self) -> DHParameterNumbers:
"""
Returns a DHParameterNumbers.
"""
DHParametersWithSerialization = DHParameters
class DHPublicKey(metaclass=abc.ABCMeta):
@abc.abstractproperty
def key_size(self) -> int:
"""
The bit length of the prime modulus.
"""
@abc.abstractmethod
def parameters(self) -> DHParameters:
"""
The DHParameters object associated with this public key.
"""
@abc.abstractmethod
def public_numbers(self) -> DHPublicNumbers:
"""
Returns a DHPublicNumbers.
"""
@abc.abstractmethod
def public_bytes(
self,
encoding: "serialization.Encoding",
format: "serialization.PublicFormat",
) -> bytes:
"""
Returns the key serialized as bytes.
"""
DHPublicKeyWithSerialization = DHPublicKey
class DHPrivateKey(metaclass=abc.ABCMeta):
@abc.abstractproperty
def key_size(self) -> int:
"""
The bit length of the prime modulus.
"""
@abc.abstractmethod
def public_key(self) -> DHPublicKey:
"""
The DHPublicKey associated with this private key.
"""
@abc.abstractmethod
def parameters(self) -> DHParameters:
"""
The DHParameters object associated with this private key.
"""
@abc.abstractmethod
def exchange(self, peer_public_key: DHPublicKey) -> bytes:
"""
Given peer's DHPublicKey, carry out the key exchange and
return shared key as bytes.
"""
@abc.abstractmethod
def private_numbers(self) -> DHPrivateNumbers:
"""
Returns a DHPrivateNumbers.
"""
@abc.abstractmethod
def private_bytes(
self,
encoding: "serialization.Encoding",
format: "serialization.PrivateFormat",
encryption_algorithm: "serialization.KeySerializationEncryption",
) -> bytes:
"""
Returns the key serialized as bytes.
"""
DHPrivateKeyWithSerialization = DHPrivateKey
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