# 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, hashes from cryptography.hazmat.primitives.asymmetric import ( AsymmetricSignatureContext, AsymmetricVerificationContext, utils as asym_utils, ) class DSAParameters(metaclass=abc.ABCMeta): @abc.abstractmethod def generate_private_key(self) -> "DSAPrivateKey": """ Generates and returns a DSAPrivateKey. """ @abc.abstractmethod def parameter_numbers(self) -> "DSAParameterNumbers": """ Returns a DSAParameterNumbers. """ DSAParametersWithNumbers = DSAParameters class DSAPrivateKey(metaclass=abc.ABCMeta): @abc.abstractproperty def key_size(self) -> int: """ The bit length of the prime modulus. """ @abc.abstractmethod def public_key(self) -> "DSAPublicKey": """ The DSAPublicKey associated with this private key. """ @abc.abstractmethod def parameters(self) -> DSAParameters: """ The DSAParameters object associated with this private key. """ @abc.abstractmethod def signer( self, signature_algorithm: hashes.HashAlgorithm, ) -> AsymmetricSignatureContext: """ Returns an AsymmetricSignatureContext used for signing data. """ @abc.abstractmethod def sign( self, data: bytes, algorithm: typing.Union[asym_utils.Prehashed, hashes.HashAlgorithm], ) -> bytes: """ Signs the data """ @abc.abstractmethod def private_numbers(self) -> "DSAPrivateNumbers": """ Returns a DSAPrivateNumbers. """ @abc.abstractmethod def private_bytes( self, encoding: _serialization.Encoding, format: _serialization.PrivateFormat, encryption_algorithm: _serialization.KeySerializationEncryption, ) -> bytes: """ Returns the key serialized as bytes. """ DSAPrivateKeyWithSerialization = DSAPrivateKey class DSAPublicKey(metaclass=abc.ABCMeta): @abc.abstractproperty def key_size(self) -> int: """ The bit length of the prime modulus. """ @abc.abstractmethod def parameters(self) -> DSAParameters: """ The DSAParameters object associated with this public key. """ @abc.abstractmethod def verifier( self, signature: bytes, signature_algorithm: hashes.HashAlgorithm, ) -> AsymmetricVerificationContext: """ Returns an AsymmetricVerificationContext used for signing data. """ @abc.abstractmethod def public_numbers(self) -> "DSAPublicNumbers": """ Returns a DSAPublicNumbers. """ @abc.abstractmethod def public_bytes( self, encoding: _serialization.Encoding, format: _serialization.PublicFormat, ) -> bytes: """ Returns the key serialized as bytes. """ @abc.abstractmethod def verify( self, signature: bytes, data: bytes, algorithm: typing.Union[asym_utils.Prehashed, hashes.HashAlgorithm], ) -> None: """ Verifies the signature of the data. """ DSAPublicKeyWithSerialization = DSAPublicKey class DSAParameterNumbers(object): def __init__(self, p: int, q: int, g: int): if ( not isinstance(p, int) or not isinstance(q, int) or not isinstance(g, int) ): raise TypeError( "DSAParameterNumbers p, q, and g arguments must be integers." ) self._p = p self._q = q self._g = g p = property(lambda self: self._p) q = property(lambda self: self._q) g = property(lambda self: self._g) def parameters(self, backend: typing.Any = None) -> DSAParameters: from cryptography.hazmat.backends.openssl.backend import ( backend as ossl, ) return ossl.load_dsa_parameter_numbers(self) def __eq__(self, other): if not isinstance(other, DSAParameterNumbers): return NotImplemented return self.p == other.p and self.q == other.q and self.g == other.g def __ne__(self, other): return not self == other def __repr__(self): return ( "".format(self=self) ) class DSAPublicNumbers(object): def __init__(self, y: int, parameter_numbers: DSAParameterNumbers): if not isinstance(y, int): raise TypeError("DSAPublicNumbers y argument must be an integer.") if not isinstance(parameter_numbers, DSAParameterNumbers): raise TypeError( "parameter_numbers must be a DSAParameterNumbers instance." ) self._y = y self._parameter_numbers = parameter_numbers y = property(lambda self: self._y) parameter_numbers = property(lambda self: self._parameter_numbers) def public_key(self, backend: typing.Any = None) -> DSAPublicKey: from cryptography.hazmat.backends.openssl.backend import ( backend as ossl, ) return ossl.load_dsa_public_numbers(self) def __eq__(self, other): if not isinstance(other, DSAPublicNumbers): return NotImplemented return ( self.y == other.y and self.parameter_numbers == other.parameter_numbers ) def __ne__(self, other): return not self == other def __repr__(self): return ( "".format(self=self) ) class DSAPrivateNumbers(object): def __init__(self, x: int, public_numbers: DSAPublicNumbers): if not isinstance(x, int): raise TypeError("DSAPrivateNumbers x argument must be an integer.") if not isinstance(public_numbers, DSAPublicNumbers): raise TypeError( "public_numbers must be a DSAPublicNumbers instance." ) self._public_numbers = public_numbers self._x = x x = property(lambda self: self._x) public_numbers = property(lambda self: self._public_numbers) def private_key(self, backend: typing.Any = None) -> DSAPrivateKey: from cryptography.hazmat.backends.openssl.backend import ( backend as ossl, ) return ossl.load_dsa_private_numbers(self) def __eq__(self, other): if not isinstance(other, DSAPrivateNumbers): return NotImplemented return ( self.x == other.x and self.public_numbers == other.public_numbers ) def __ne__(self, other): return not self == other def generate_parameters( key_size: int, backend: typing.Any = None ) -> DSAParameters: from cryptography.hazmat.backends.openssl.backend import backend as ossl return ossl.generate_dsa_parameters(key_size) def generate_private_key( key_size: int, backend: typing.Any = None ) -> DSAPrivateKey: from cryptography.hazmat.backends.openssl.backend import backend as ossl return ossl.generate_dsa_private_key_and_parameters(key_size) def _check_dsa_parameters(parameters: DSAParameterNumbers) -> None: if parameters.p.bit_length() not in [1024, 2048, 3072, 4096]: raise ValueError( "p must be exactly 1024, 2048, 3072, or 4096 bits long" ) if parameters.q.bit_length() not in [160, 224, 256]: raise ValueError("q must be exactly 160, 224, or 256 bits long") if not (1 < parameters.g < parameters.p): raise ValueError("g, p don't satisfy 1 < g < p.") def _check_dsa_private_numbers(numbers: DSAPrivateNumbers) -> None: parameters = numbers.public_numbers.parameter_numbers _check_dsa_parameters(parameters) if numbers.x <= 0 or numbers.x >= parameters.q: raise ValueError("x must be > 0 and < q.") if numbers.public_numbers.y != pow(parameters.g, numbers.x, parameters.p): raise ValueError("y must be equal to (g ** x % p).")