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https://github.com/varun-r-mallya/py-libp2p.git
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60 lines
1.5 KiB
Python
60 lines
1.5 KiB
Python
import sys
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from typing import (
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Callable,
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cast,
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)
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if sys.platform != "win32":
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from fastecdsa.encoding import (
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util,
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)
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int_bytelen = util.int_bytelen
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else:
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from math import (
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ceil,
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log2,
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)
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def int_bytelen(n: int) -> int:
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if n == 0:
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return 1
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return ceil(log2(abs(n) + 1) / 8)
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from libp2p.crypto.ecc import (
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ECCPrivateKey,
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ECCPublicKey,
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create_new_key_pair,
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)
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from libp2p.crypto.keys import (
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PublicKey,
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)
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SharedKeyGenerator = Callable[[bytes], bytes]
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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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if sys.platform != "win32":
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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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else:
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# Windows implementation using coincurve
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shared_key = private_key.impl.ecdh(remote_point.impl.public_key)
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return shared_key
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return key_pair.public_key, _key_exchange
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