trezor-firmware/core/src/apps/binance/sign_tx.py

from trezor import wire
from trezor.crypto.curve import secp256k1
from trezor.crypto.hashlib import sha256
from trezor.messages import MessageType
from trezor.messages.BinanceCancelMsg import BinanceCancelMsg
from trezor.messages.BinanceOrderMsg import BinanceOrderMsg
from trezor.messages.BinanceSignedTx import BinanceSignedTx
from trezor.messages.BinanceTransferMsg import BinanceTransferMsg
from trezor.messages.BinanceTxRequest import BinanceTxRequest

from apps.common import paths
from apps.common.keychain import Keychain, auto_keychain

from . import helpers, layout


@auto_keychain(__name__)
async def sign_tx(ctx, envelope, keychain: Keychain):
    # create transaction message -> sign it -> create signature/pubkey message -> serialize all
    if envelope.msg_count > 1:
        raise wire.DataError("Multiple messages not supported.")

    await paths.validate_path(ctx, keychain, envelope.address_n)
    node = keychain.derive(envelope.address_n)

    tx_req = BinanceTxRequest()

    msg = await ctx.call_any(
        tx_req,
        MessageType.BinanceCancelMsg,
        MessageType.BinanceOrderMsg,
        MessageType.BinanceTransferMsg,
    )

    if envelope.source is None or envelope.source < 0:
        raise wire.DataError("Source missing or invalid.")

    msg_json = helpers.produce_json_for_signing(envelope, msg)

    if isinstance(msg, BinanceTransferMsg):
        await layout.require_confirm_transfer(ctx, msg)
    elif isinstance(msg, BinanceOrderMsg):
        await layout.require_confirm_order(ctx, msg)
    elif isinstance(msg, BinanceCancelMsg):
        await layout.require_confirm_cancel(ctx, msg)
    else:
        raise ValueError("input message unrecognized, is of type " + type(msg).__name__)

    signature_bytes = generate_content_signature(msg_json.encode(), node.private_key())

    return BinanceSignedTx(signature=signature_bytes, public_key=node.public_key())


def generate_content_signature(json: bytes, private_key: bytes) -> bytes:
    msghash = sha256(json).digest()
    return secp256k1.sign(private_key, msghash)[1:65]