trezor-firmware/core/src/apps/bitcoin/authorization.py

from micropython import const

from trezor.messages import MessageType

from .common import BIP32_WALLET_DEPTH

if False:
    from typing import Iterable
    from trezor.messages.AuthorizeCoinJoin import AuthorizeCoinJoin
    from trezor.messages.GetOwnershipProof import GetOwnershipProof
    from trezor.messages.SignTx import SignTx
    from trezor.messages.TxInput import TxInput

    from apps.common.coininfo import CoinInfo
    from apps.common.keychain import Keychain

_ROUND_ID_LEN = const(32)
FEE_PER_ANONYMITY_DECIMALS = const(9)


class CoinJoinAuthorization:
    def __init__(
        self, msg: AuthorizeCoinJoin, keychain: Keychain, coin: CoinInfo
    ) -> None:
        self.coordinator = msg.coordinator
        self.remaining_fee = msg.max_total_fee
        self.fee_per_anonymity = msg.fee_per_anonymity or 0
        self.address_n = msg.address_n
        self.keychain = keychain
        self.coin = coin
        self.script_type = msg.script_type

    def __del__(self) -> None:
        self.keychain.__del__()

    def expected_wire_types(self) -> Iterable[int]:
        return (MessageType.SignTx, MessageType.GetOwnershipProof)

    def check_get_ownership_proof(self, msg: GetOwnershipProof) -> bool:
        # Check whether the current authorization matches the parameters of the request.
        return (
            len(msg.address_n) >= BIP32_WALLET_DEPTH
            and msg.address_n[:-BIP32_WALLET_DEPTH] == self.address_n
            and msg.coin_name == self.coin.coin_name
            and msg.script_type == self.script_type
            and len(msg.commitment_data) >= _ROUND_ID_LEN
            and msg.commitment_data[:-_ROUND_ID_LEN] == self.coordinator.encode()
        )

    def check_sign_tx_input(self, txi: TxInput, coin: CoinInfo) -> bool:
        # Check whether the current input matches the parameters of the request.
        return (
            len(txi.address_n) >= BIP32_WALLET_DEPTH
            and txi.address_n[:-BIP32_WALLET_DEPTH] == self.address_n
            and coin.coin_name == self.coin.coin_name
            and txi.script_type == self.script_type
        )

    def approve_sign_tx(self, msg: SignTx, fee: int) -> bool:
        if self.remaining_fee < fee or msg.coin_name != self.coin.coin_name:
            return False

        self.remaining_fee -= fee
        return True