440 lines
11 KiB
Python
440 lines
11 KiB
Python
# This file is dual licensed under the terms of the Apache License, Version
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# 2.0, and the BSD License. See the LICENSE file in the root of this repository
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# for complete details.
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from __future__ import annotations
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import abc
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import typing
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from math import gcd
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from cryptography.hazmat.primitives import _serialization, hashes
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from cryptography.hazmat.primitives._asymmetric import AsymmetricPadding
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from cryptography.hazmat.primitives.asymmetric import utils as asym_utils
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class RSAPrivateKey(metaclass=abc.ABCMeta):
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@abc.abstractmethod
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def decrypt(self, ciphertext: bytes, padding: AsymmetricPadding) -> bytes:
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"""
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Decrypts the provided ciphertext.
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"""
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@property
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@abc.abstractmethod
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def key_size(self) -> int:
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"""
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The bit length of the public modulus.
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"""
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@abc.abstractmethod
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def public_key(self) -> RSAPublicKey:
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"""
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The RSAPublicKey associated with this private key.
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"""
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@abc.abstractmethod
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def sign(
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self,
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data: bytes,
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padding: AsymmetricPadding,
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algorithm: typing.Union[asym_utils.Prehashed, hashes.HashAlgorithm],
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) -> bytes:
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"""
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Signs the data.
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"""
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@abc.abstractmethod
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def private_numbers(self) -> RSAPrivateNumbers:
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"""
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Returns an RSAPrivateNumbers.
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"""
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@abc.abstractmethod
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def private_bytes(
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self,
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encoding: _serialization.Encoding,
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format: _serialization.PrivateFormat,
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encryption_algorithm: _serialization.KeySerializationEncryption,
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) -> bytes:
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"""
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Returns the key serialized as bytes.
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"""
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RSAPrivateKeyWithSerialization = RSAPrivateKey
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class RSAPublicKey(metaclass=abc.ABCMeta):
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@abc.abstractmethod
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def encrypt(self, plaintext: bytes, padding: AsymmetricPadding) -> bytes:
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"""
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Encrypts the given plaintext.
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"""
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@property
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@abc.abstractmethod
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def key_size(self) -> int:
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"""
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The bit length of the public modulus.
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"""
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@abc.abstractmethod
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def public_numbers(self) -> RSAPublicNumbers:
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"""
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Returns an RSAPublicNumbers
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"""
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@abc.abstractmethod
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def public_bytes(
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self,
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encoding: _serialization.Encoding,
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format: _serialization.PublicFormat,
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) -> bytes:
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"""
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Returns the key serialized as bytes.
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"""
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@abc.abstractmethod
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def verify(
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self,
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signature: bytes,
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data: bytes,
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padding: AsymmetricPadding,
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algorithm: typing.Union[asym_utils.Prehashed, hashes.HashAlgorithm],
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) -> None:
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"""
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Verifies the signature of the data.
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"""
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@abc.abstractmethod
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def recover_data_from_signature(
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self,
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signature: bytes,
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padding: AsymmetricPadding,
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algorithm: typing.Optional[hashes.HashAlgorithm],
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) -> bytes:
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"""
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Recovers the original data from the signature.
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"""
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@abc.abstractmethod
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def __eq__(self, other: object) -> bool:
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"""
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Checks equality.
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"""
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RSAPublicKeyWithSerialization = RSAPublicKey
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def generate_private_key(
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public_exponent: int,
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key_size: int,
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backend: typing.Any = None,
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) -> RSAPrivateKey:
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from cryptography.hazmat.backends.openssl.backend import backend as ossl
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_verify_rsa_parameters(public_exponent, key_size)
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return ossl.generate_rsa_private_key(public_exponent, key_size)
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def _verify_rsa_parameters(public_exponent: int, key_size: int) -> None:
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if public_exponent not in (3, 65537):
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raise ValueError(
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"public_exponent must be either 3 (for legacy compatibility) or "
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"65537. Almost everyone should choose 65537 here!"
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)
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if key_size < 512:
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raise ValueError("key_size must be at least 512-bits.")
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def _check_private_key_components(
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p: int,
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q: int,
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private_exponent: int,
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dmp1: int,
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dmq1: int,
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iqmp: int,
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public_exponent: int,
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modulus: int,
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) -> None:
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if modulus < 3:
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raise ValueError("modulus must be >= 3.")
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if p >= modulus:
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raise ValueError("p must be < modulus.")
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if q >= modulus:
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raise ValueError("q must be < modulus.")
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if dmp1 >= modulus:
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raise ValueError("dmp1 must be < modulus.")
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if dmq1 >= modulus:
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raise ValueError("dmq1 must be < modulus.")
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if iqmp >= modulus:
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raise ValueError("iqmp must be < modulus.")
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if private_exponent >= modulus:
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raise ValueError("private_exponent must be < modulus.")
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if public_exponent < 3 or public_exponent >= modulus:
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raise ValueError("public_exponent must be >= 3 and < modulus.")
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if public_exponent & 1 == 0:
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raise ValueError("public_exponent must be odd.")
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if dmp1 & 1 == 0:
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raise ValueError("dmp1 must be odd.")
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if dmq1 & 1 == 0:
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raise ValueError("dmq1 must be odd.")
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if p * q != modulus:
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raise ValueError("p*q must equal modulus.")
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def _check_public_key_components(e: int, n: int) -> None:
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if n < 3:
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raise ValueError("n must be >= 3.")
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if e < 3 or e >= n:
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raise ValueError("e must be >= 3 and < n.")
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if e & 1 == 0:
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raise ValueError("e must be odd.")
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def _modinv(e: int, m: int) -> int:
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"""
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Modular Multiplicative Inverse. Returns x such that: (x*e) mod m == 1
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"""
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x1, x2 = 1, 0
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a, b = e, m
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while b > 0:
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q, r = divmod(a, b)
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xn = x1 - q * x2
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a, b, x1, x2 = b, r, x2, xn
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return x1 % m
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def rsa_crt_iqmp(p: int, q: int) -> int:
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"""
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Compute the CRT (q ** -1) % p value from RSA primes p and q.
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"""
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return _modinv(q, p)
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def rsa_crt_dmp1(private_exponent: int, p: int) -> int:
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"""
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Compute the CRT private_exponent % (p - 1) value from the RSA
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private_exponent (d) and p.
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"""
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return private_exponent % (p - 1)
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def rsa_crt_dmq1(private_exponent: int, q: int) -> int:
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"""
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Compute the CRT private_exponent % (q - 1) value from the RSA
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private_exponent (d) and q.
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"""
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return private_exponent % (q - 1)
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# Controls the number of iterations rsa_recover_prime_factors will perform
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# to obtain the prime factors. Each iteration increments by 2 so the actual
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# maximum attempts is half this number.
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_MAX_RECOVERY_ATTEMPTS = 1000
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def rsa_recover_prime_factors(
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n: int, e: int, d: int
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) -> typing.Tuple[int, int]:
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"""
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Compute factors p and q from the private exponent d. We assume that n has
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no more than two factors. This function is adapted from code in PyCrypto.
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"""
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# See 8.2.2(i) in Handbook of Applied Cryptography.
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ktot = d * e - 1
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# The quantity d*e-1 is a multiple of phi(n), even,
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# and can be represented as t*2^s.
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t = ktot
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while t % 2 == 0:
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t = t // 2
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# Cycle through all multiplicative inverses in Zn.
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# The algorithm is non-deterministic, but there is a 50% chance
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# any candidate a leads to successful factoring.
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# See "Digitalized Signatures and Public Key Functions as Intractable
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# as Factorization", M. Rabin, 1979
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spotted = False
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a = 2
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while not spotted and a < _MAX_RECOVERY_ATTEMPTS:
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k = t
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# Cycle through all values a^{t*2^i}=a^k
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while k < ktot:
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cand = pow(a, k, n)
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# Check if a^k is a non-trivial root of unity (mod n)
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if cand != 1 and cand != (n - 1) and pow(cand, 2, n) == 1:
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# We have found a number such that (cand-1)(cand+1)=0 (mod n).
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# Either of the terms divides n.
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p = gcd(cand + 1, n)
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spotted = True
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break
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k *= 2
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# This value was not any good... let's try another!
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a += 2
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if not spotted:
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raise ValueError("Unable to compute factors p and q from exponent d.")
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# Found !
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q, r = divmod(n, p)
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assert r == 0
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p, q = sorted((p, q), reverse=True)
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return (p, q)
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class RSAPrivateNumbers:
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def __init__(
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self,
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p: int,
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q: int,
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d: int,
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dmp1: int,
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dmq1: int,
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iqmp: int,
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public_numbers: RSAPublicNumbers,
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):
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if (
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not isinstance(p, int)
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or not isinstance(q, int)
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or not isinstance(d, int)
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or not isinstance(dmp1, int)
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or not isinstance(dmq1, int)
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or not isinstance(iqmp, int)
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):
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raise TypeError(
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"RSAPrivateNumbers p, q, d, dmp1, dmq1, iqmp arguments must"
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" all be an integers."
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)
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if not isinstance(public_numbers, RSAPublicNumbers):
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raise TypeError(
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"RSAPrivateNumbers public_numbers must be an RSAPublicNumbers"
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" instance."
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)
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self._p = p
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self._q = q
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self._d = d
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self._dmp1 = dmp1
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self._dmq1 = dmq1
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self._iqmp = iqmp
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self._public_numbers = public_numbers
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@property
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def p(self) -> int:
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return self._p
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@property
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def q(self) -> int:
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return self._q
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@property
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def d(self) -> int:
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return self._d
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@property
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def dmp1(self) -> int:
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return self._dmp1
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@property
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def dmq1(self) -> int:
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return self._dmq1
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@property
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def iqmp(self) -> int:
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return self._iqmp
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@property
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def public_numbers(self) -> RSAPublicNumbers:
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return self._public_numbers
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def private_key(
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self,
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backend: typing.Any = None,
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*,
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unsafe_skip_rsa_key_validation: bool = False,
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) -> RSAPrivateKey:
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from cryptography.hazmat.backends.openssl.backend import (
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backend as ossl,
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)
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return ossl.load_rsa_private_numbers(
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self, unsafe_skip_rsa_key_validation
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)
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, RSAPrivateNumbers):
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return NotImplemented
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return (
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self.p == other.p
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and self.q == other.q
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and self.d == other.d
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and self.dmp1 == other.dmp1
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and self.dmq1 == other.dmq1
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and self.iqmp == other.iqmp
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and self.public_numbers == other.public_numbers
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)
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def __hash__(self) -> int:
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return hash(
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(
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self.p,
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self.q,
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self.d,
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self.dmp1,
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self.dmq1,
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self.iqmp,
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self.public_numbers,
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)
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)
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class RSAPublicNumbers:
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def __init__(self, e: int, n: int):
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if not isinstance(e, int) or not isinstance(n, int):
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raise TypeError("RSAPublicNumbers arguments must be integers.")
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self._e = e
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self._n = n
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@property
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def e(self) -> int:
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return self._e
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@property
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def n(self) -> int:
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return self._n
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def public_key(self, backend: typing.Any = None) -> RSAPublicKey:
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from cryptography.hazmat.backends.openssl.backend import (
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backend as ossl,
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)
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return ossl.load_rsa_public_numbers(self)
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def __repr__(self) -> str:
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return "<RSAPublicNumbers(e={0.e}, n={0.n})>".format(self)
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, RSAPublicNumbers):
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return NotImplemented
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return self.e == other.e and self.n == other.n
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def __hash__(self) -> int:
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return hash((self.e, self.n))
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