142 lines
5 KiB
Python
142 lines
5 KiB
Python
from string import hexdigits
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import ecdsa
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import hashlib
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import binascii
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from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.serialization import load_der_public_key
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives.asymmetric import ec
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from cryptography.hazmat.primitives.asymmetric.utils import Prehashed
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from cryptography.exceptions import InvalidSignature
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from ecdsa.util import sigencode_der
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from lbrynet.schema.address import decode_address
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from lbrynet.schema.constants import NIST256p, NIST384p, SECP256k1, ECDSA_CURVES, CURVE_NAMES
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def validate_claim_id(claim_id):
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if not len(claim_id) == 40:
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raise Exception("Incorrect claimid length: %i" % len(claim_id))
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if isinstance(claim_id, bytes):
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claim_id = claim_id.decode('utf-8')
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if set(claim_id).difference(hexdigits):
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raise Exception("Claim id is not hex encoded")
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class Validator:
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CURVE_NAME = None
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HASHFUNC = hashlib.sha256
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def __init__(self, public_key, certificate_claim_id):
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validate_claim_id(certificate_claim_id)
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if CURVE_NAMES.get(get_key_type_from_dem(public_key)) != self.CURVE_NAME:
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raise Exception("Curve mismatch")
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self._public_key = public_key
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self._certificate_claim_id = certificate_claim_id
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@property
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def public_key(self):
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return self._public_key
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@property
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def certificate_claim_id(self):
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return self._certificate_claim_id
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@classmethod
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def signing_key_from_pem(cls, pem):
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return ecdsa.SigningKey.from_pem(pem, hashfunc=cls.HASHFUNC)
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@classmethod
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def signing_key_from_der(cls, der):
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return ecdsa.SigningKey.from_der(der, hashfunc=cls.HASHFUNC)
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@classmethod
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def load_from_certificate(cls, certificate_claim, certificate_claim_id):
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certificate = certificate_claim.certificate
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return cls(certificate.publicKey, certificate_claim_id)
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def validate_signature(self, digest, signature):
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public_key = load_der_public_key(self.public_key, default_backend())
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if len(signature) == 64:
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hash = hashes.SHA256()
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elif len(signature) == 96:
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hash = hashes.SHA384()
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signature = binascii.hexlify(signature)
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r = int(signature[:int(len(signature)/2)], 16)
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s = int(signature[int(len(signature)/2):], 16)
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encoded_sig = sigencode_der(r, s, len(signature)*4)
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try:
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public_key.verify(encoded_sig, digest, ec.ECDSA(Prehashed(hash)))
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return True
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except InvalidSignature:
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# TODO Fixme. This is what is expected today on the outer calls. This should be implementation independent
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# but requires changing everything calling that
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from ecdsa import BadSignatureError
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raise BadSignatureError
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def validate_claim_signature(self, claim, claim_address, name):
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to_sign = bytearray()
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if claim.detached_signature and claim.detached_signature.raw_signature:
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assert name is not None, "Name is required for verifying detached signatures."
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to_sign.extend(name.lower().encode())
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signature = claim.detached_signature.raw_signature
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payload = claim.detached_signature.payload
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else:
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# extract and serialize the stream from the claim, then check the signature
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signature = binascii.unhexlify(claim.signature)
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payload = claim.serialized_no_signature
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decoded_address = decode_address(claim_address)
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if signature is None:
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raise Exception("No signature to validate")
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to_sign.extend(decoded_address)
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to_sign.extend(payload)
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to_sign.extend(binascii.unhexlify(self.certificate_claim_id))
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return self.validate_signature(self.HASHFUNC(to_sign).digest(), signature)
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def validate_private_key(self, private_key):
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if not isinstance(private_key, ecdsa.SigningKey):
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raise TypeError("Not given a signing key, given a %s" % str(type(private_key)))
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return private_key.get_verifying_key().to_der() == self.public_key
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class NIST256pValidator(Validator):
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CURVE_NAME = NIST256p
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HASHFUNC = hashlib.sha256
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class NIST384pValidator(Validator):
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CURVE_NAME = NIST384p
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HASHFUNC = hashlib.sha384
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class SECP256k1Validator(Validator):
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CURVE_NAME = SECP256k1
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HASHFUNC = hashlib.sha256
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def get_validator(curve):
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if curve == NIST256p:
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return NIST256pValidator
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elif curve == NIST384p:
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return NIST384pValidator
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elif curve == SECP256k1:
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return SECP256k1Validator
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else:
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raise Exception("Unknown curve: %s" % str(curve))
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def get_key_type_from_dem(pubkey_dem):
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name = serialization.load_der_public_key(pubkey_dem, default_backend()).curve.name
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if name == 'secp256k1':
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return ECDSA_CURVES[SECP256k1]
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elif name == 'secp256r1':
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return ECDSA_CURVES[NIST256p]
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elif name == 'secp384r1':
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return ECDSA_CURVES[NIST384p]
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raise Exception("unexpected curve: %s" % name)
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