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63 lines
2.2 KiB
Python
63 lines
2.2 KiB
Python
from typing import TYPE_CHECKING
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if TYPE_CHECKING:
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from trezor.messages import GetECDHSessionKey, ECDHSessionKey
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# This module implements the SLIP-0017 Elliptic Curve Diffie-Hellman algorithm, using a
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# deterministic hierarchy, see https://github.com/satoshilabs/slips/blob/master/slip-0017.md.
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async def get_ecdh_session_key(msg: GetECDHSessionKey) -> ECDHSessionKey:
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from trezor.ui.layouts import confirm_address
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from .sign_identity import (
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get_identity_path,
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serialize_identity_without_proto,
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serialize_identity,
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)
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from trezor.wire import DataError
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from trezor.messages import ECDHSessionKey
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from apps.common.keychain import get_keychain
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from apps.common.paths import AlwaysMatchingSchema
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msg_identity = msg.identity # local_cache_attribute
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peer_public_key = msg.peer_public_key # local_cache_attribute
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curve_name = msg.ecdsa_curve_name or "secp256k1"
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keychain = await get_keychain(curve_name, [AlwaysMatchingSchema])
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identity = serialize_identity(msg_identity)
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# require_confirm_ecdh_session_key
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proto = msg_identity.proto.upper() if msg_identity.proto else "identity"
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await confirm_address(
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f"Decrypt {proto}",
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serialize_identity_without_proto(msg_identity),
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None,
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)
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# END require_confirm_ecdh_session_key
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address_n = get_identity_path(identity, msg_identity.index or 0, 17)
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node = keychain.derive(address_n)
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# ecdh
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if curve_name == "secp256k1":
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from trezor.crypto.curve import secp256k1
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session_key = secp256k1.multiply(node.private_key(), peer_public_key)
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elif curve_name == "nist256p1":
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from trezor.crypto.curve import nist256p1
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session_key = nist256p1.multiply(node.private_key(), peer_public_key)
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elif curve_name == "curve25519":
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from trezor.crypto.curve import curve25519
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if peer_public_key[0] != 0x40:
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raise DataError("Curve25519 public key should start with 0x40")
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session_key = b"\x04" + curve25519.multiply(
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node.private_key(), peer_public_key[1:]
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)
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else:
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raise DataError("Unsupported curve for ECDH: " + curve_name)
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# END ecdh
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return ECDHSessionKey(session_key=session_key, public_key=node.public_key())
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