27ecd4b0ed
It seems preferable to import just fastecdsa. But if you do that, then some kind of side-effect doesn't happen, which means that `sec1` is not available as an attribute on `fastecdsa.encoding`. So we specifically mock the sub-modules as well.
30 lines
1.0 KiB
Python
30 lines
1.0 KiB
Python
from typing import Callable, Tuple, cast
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from fastecdsa.encoding import util
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from libp2p.crypto.ecc import ECCPrivateKey, ECCPublicKey, create_new_key_pair
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from libp2p.crypto.keys import PublicKey
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SharedKeyGenerator = Callable[[bytes], bytes]
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int_bytelen = util.int_bytelen
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def create_ephemeral_key_pair(curve_type: str) -> Tuple[PublicKey, SharedKeyGenerator]:
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"""Facilitates ECDH key exchange."""
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if curve_type != "P-256":
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raise NotImplementedError()
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key_pair = create_new_key_pair(curve_type)
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def _key_exchange(serialized_remote_public_key: bytes) -> bytes:
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private_key = cast(ECCPrivateKey, key_pair.private_key)
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remote_point = ECCPublicKey.from_bytes(serialized_remote_public_key, curve_type)
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secret_point = remote_point.impl * private_key.impl
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secret_x_coordinate = secret_point.x
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byte_size = int_bytelen(secret_x_coordinate)
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return secret_x_coordinate.to_bytes(byte_size, byteorder="big")
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return key_pair.public_key, _key_exchange
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