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dh.py
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dh.py
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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.hazmat.primitives import _serialization
_MIN_MODULUS_SIZE = 512
def generate_parameters(
generator: int, key_size: int, backend: typing.Any = None
) -> "DHParameters":
from cryptography.hazmat.backends.openssl.backend import backend as ossl
return ossl.generate_dh_parameters(generator, key_size)
class DHParameterNumbers:
def __init__(self, p: int, g: int, q: typing.Optional[int] = None) -> 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(
f"p (modulus) must be at least {_MIN_MODULUS_SIZE}-bit"
)
self._p = p
self._g = g
self._q = q
def __eq__(self, other: object) -> bool:
if not isinstance(other, DHParameterNumbers):
return NotImplemented
return (
self._p == other._p and self._g == other._g and self._q == other._q
)
def parameters(self, backend: typing.Any = None) -> "DHParameters":
from cryptography.hazmat.backends.openssl.backend import (
backend as ossl,
)
return ossl.load_dh_parameter_numbers(self)
@property
def p(self) -> int:
return self._p
@property
def g(self) -> int:
return self._g
@property
def q(self) -> typing.Optional[int]:
return self._q
class DHPublicNumbers:
def __init__(self, y: int, parameter_numbers: DHParameterNumbers) -> None:
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: object) -> bool:
if not isinstance(other, DHPublicNumbers):
return NotImplemented
return (
self._y == other._y
and self._parameter_numbers == other._parameter_numbers
)
def public_key(self, backend: typing.Any = None) -> "DHPublicKey":
from cryptography.hazmat.backends.openssl.backend import (
backend as ossl,
)
return ossl.load_dh_public_numbers(self)
@property
def y(self) -> int:
return self._y
@property
def parameter_numbers(self) -> DHParameterNumbers:
return self._parameter_numbers
class DHPrivateNumbers:
def __init__(self, x: int, public_numbers: DHPublicNumbers) -> None:
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: object) -> bool:
if not isinstance(other, DHPrivateNumbers):
return NotImplemented
return (
self._x == other._x
and self._public_numbers == other._public_numbers
)
def private_key(self, backend: typing.Any = None) -> "DHPrivateKey":
from cryptography.hazmat.backends.openssl.backend import (
backend as ossl,
)
return ossl.load_dh_private_numbers(self)
@property
def public_numbers(self) -> DHPublicNumbers:
return self._public_numbers
@property
def x(self) -> int:
return self._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):
@property
@abc.abstractmethod
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):
@property
@abc.abstractmethod
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