98 lines
3.1 KiB
Python
98 lines
3.1 KiB
Python
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 ec, utils
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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 PublicECDSA(CryptographyPublicKey):
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key: ec.EllipticCurvePublicKey
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key_cls = ec.EllipticCurvePublicKey
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algorithm: Algorithm
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chosen_hash: hashes.HashAlgorithm
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curve: ec.EllipticCurve
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octets: int
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def verify(self, signature: bytes, data: bytes) -> None:
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sig_r = signature[0 : self.octets]
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sig_s = signature[self.octets :]
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sig = utils.encode_dss_signature(
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int.from_bytes(sig_r, "big"), int.from_bytes(sig_s, "big")
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)
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self.key.verify(sig, data, ec.ECDSA(self.chosen_hash))
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def encode_key_bytes(self) -> bytes:
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"""Encode a public key per RFC 6605, section 4."""
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pn = self.key.public_numbers()
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return pn.x.to_bytes(self.octets, "big") + pn.y.to_bytes(self.octets, "big")
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@classmethod
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def from_dnskey(cls, key: DNSKEY) -> "PublicECDSA":
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cls._ensure_algorithm_key_combination(key)
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ecdsa_x = key.key[0 : cls.octets]
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ecdsa_y = key.key[cls.octets : cls.octets * 2]
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return cls(
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key=ec.EllipticCurvePublicNumbers(
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curve=cls.curve,
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x=int.from_bytes(ecdsa_x, "big"),
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y=int.from_bytes(ecdsa_y, "big"),
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).public_key(default_backend()),
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)
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class PrivateECDSA(CryptographyPrivateKey):
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key: ec.EllipticCurvePrivateKey
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key_cls = ec.EllipticCurvePrivateKey
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public_cls = PublicECDSA
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def sign(
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self,
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data: bytes,
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verify: bool = False,
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deterministic: bool = True,
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) -> bytes:
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"""Sign using a private key per RFC 6605, section 4."""
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algorithm = ec.ECDSA(
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self.public_cls.chosen_hash, deterministic_signing=deterministic
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)
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der_signature = self.key.sign(data, algorithm)
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dsa_r, dsa_s = utils.decode_dss_signature(der_signature)
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signature = int.to_bytes(
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dsa_r, length=self.public_cls.octets, byteorder="big"
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) + int.to_bytes(dsa_s, length=self.public_cls.octets, byteorder="big")
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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) -> "PrivateECDSA":
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return cls(
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key=ec.generate_private_key(
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curve=cls.public_cls.curve, backend=default_backend()
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),
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)
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class PublicECDSAP256SHA256(PublicECDSA):
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algorithm = Algorithm.ECDSAP256SHA256
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chosen_hash = hashes.SHA256()
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curve = ec.SECP256R1()
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octets = 32
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class PrivateECDSAP256SHA256(PrivateECDSA):
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public_cls = PublicECDSAP256SHA256
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class PublicECDSAP384SHA384(PublicECDSA):
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algorithm = Algorithm.ECDSAP384SHA384
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chosen_hash = hashes.SHA384()
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curve = ec.SECP384R1()
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octets = 48
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class PrivateECDSAP384SHA384(PrivateECDSA):
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public_cls = PublicECDSAP384SHA384
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