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import math |
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import struct |
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from cryptography.hazmat.backends import default_backend |
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from cryptography.hazmat.primitives import hashes |
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from cryptography.hazmat.primitives.asymmetric import padding, rsa |
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from dns.dnssecalgs.cryptography import CryptographyPrivateKey, CryptographyPublicKey |
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from dns.dnssectypes import Algorithm |
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from dns.rdtypes.ANY.DNSKEY import DNSKEY |
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class PublicRSA(CryptographyPublicKey): |
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key: rsa.RSAPublicKey |
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key_cls = rsa.RSAPublicKey |
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algorithm: Algorithm |
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chosen_hash: hashes.HashAlgorithm |
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def verify(self, signature: bytes, data: bytes) -> None: |
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self.key.verify(signature, data, padding.PKCS1v15(), self.chosen_hash) |
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def encode_key_bytes(self) -> bytes: |
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"""Encode a public key per RFC 3110, section 2.""" |
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pn = self.key.public_numbers() |
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_exp_len = math.ceil(int.bit_length(pn.e) / 8) |
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exp = int.to_bytes(pn.e, length=_exp_len, byteorder="big") |
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if _exp_len > 255: |
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exp_header = b"\0" + struct.pack("!H", _exp_len) |
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else: |
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exp_header = struct.pack("!B", _exp_len) |
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if pn.n.bit_length() < 512 or pn.n.bit_length() > 4096: |
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raise ValueError("unsupported RSA key length") |
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return exp_header + exp + pn.n.to_bytes((pn.n.bit_length() + 7) // 8, "big") |
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@classmethod |
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def from_dnskey(cls, key: DNSKEY) -> "PublicRSA": |
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cls._ensure_algorithm_key_combination(key) |
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keyptr = key.key |
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(bytes_,) = struct.unpack("!B", keyptr[0:1]) |
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keyptr = keyptr[1:] |
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if bytes_ == 0: |
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(bytes_,) = struct.unpack("!H", keyptr[0:2]) |
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keyptr = keyptr[2:] |
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rsa_e = keyptr[0:bytes_] |
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rsa_n = keyptr[bytes_:] |
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return cls( |
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key=rsa.RSAPublicNumbers( |
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int.from_bytes(rsa_e, "big"), int.from_bytes(rsa_n, "big") |
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).public_key(default_backend()) |
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) |
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class PrivateRSA(CryptographyPrivateKey): |
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key: rsa.RSAPrivateKey |
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key_cls = rsa.RSAPrivateKey |
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public_cls = PublicRSA |
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default_public_exponent = 65537 |
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def sign(self, data: bytes, verify: bool = False) -> bytes: |
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"""Sign using a private key per RFC 3110, section 3.""" |
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signature = self.key.sign(data, padding.PKCS1v15(), self.public_cls.chosen_hash) |
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if verify: |
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self.public_key().verify(signature, data) |
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return signature |
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@classmethod |
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def generate(cls, key_size: int) -> "PrivateRSA": |
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return cls( |
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key=rsa.generate_private_key( |
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public_exponent=cls.default_public_exponent, |
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key_size=key_size, |
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backend=default_backend(), |
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) |
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) |
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class PublicRSAMD5(PublicRSA): |
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algorithm = Algorithm.RSAMD5 |
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chosen_hash = hashes.MD5() |
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class PrivateRSAMD5(PrivateRSA): |
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public_cls = PublicRSAMD5 |
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class PublicRSASHA1(PublicRSA): |
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algorithm = Algorithm.RSASHA1 |
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chosen_hash = hashes.SHA1() |
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class PrivateRSASHA1(PrivateRSA): |
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public_cls = PublicRSASHA1 |
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class PublicRSASHA1NSEC3SHA1(PublicRSA): |
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algorithm = Algorithm.RSASHA1NSEC3SHA1 |
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chosen_hash = hashes.SHA1() |
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class PrivateRSASHA1NSEC3SHA1(PrivateRSA): |
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public_cls = PublicRSASHA1NSEC3SHA1 |
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class PublicRSASHA256(PublicRSA): |
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algorithm = Algorithm.RSASHA256 |
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chosen_hash = hashes.SHA256() |
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class PrivateRSASHA256(PrivateRSA): |
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public_cls = PublicRSASHA256 |
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class PublicRSASHA512(PublicRSA): |
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algorithm = Algorithm.RSASHA512 |
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chosen_hash = hashes.SHA512() |
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class PrivateRSASHA512(PrivateRSA): |
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public_cls = PublicRSASHA512 |
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