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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.
from __future__ import absolute_import, division, print_function
import six
from cryptography import utils
def generate_parameters(key_size, backend):
return backend.generate_dsa_parameters(key_size)
def generate_private_key(key_size, backend):
return backend.generate_dsa_private_key_and_parameters(key_size)
def _check_dsa_parameters(parameters):
if utils.bit_length(parameters.p) not in [1024, 2048, 3072]:
raise ValueError("p must be exactly 1024, 2048, or 3072 bits long")
if utils.bit_length(parameters.q) not in [160, 256]:
raise ValueError("q must be exactly 160 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):
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).")
class DSAParameterNumbers(object):
def __init__(self, p, q, g):
if (
not isinstance(p, six.integer_types) or
not isinstance(q, six.integer_types) or
not isinstance(g, six.integer_types)
):
raise TypeError(
"DSAParameterNumbers p, q, and g arguments must be integers."
)
self._p = p
self._q = q
self._g = g
p = utils.read_only_property("_p")
q = utils.read_only_property("_q")
g = utils.read_only_property("_g")
def parameters(self, backend):
return backend.load_dsa_parameter_numbers(self)
class DSAPublicNumbers(object):
def __init__(self, y, parameter_numbers):
if not isinstance(y, six.integer_types):
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 = utils.read_only_property("_y")
parameter_numbers = utils.read_only_property("_parameter_numbers")
def public_key(self, backend):
return backend.load_dsa_public_numbers(self)
class DSAPrivateNumbers(object):
def __init__(self, x, public_numbers):
if not isinstance(x, six.integer_types):
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 = utils.read_only_property("_x")
public_numbers = utils.read_only_property("_public_numbers")
def private_key(self, backend):
return backend.load_dsa_private_numbers(self)
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