trezor-firmware/core/src/apps/cardano/byron_addresses.py

from typing import TYPE_CHECKING

from trezor import log, wire
from trezor.crypto import crc, hashlib

from apps.common import cbor

from .helpers import protocol_magics
from .helpers.utils import derive_public_key

if TYPE_CHECKING:
    from . import seed

PROTOCOL_MAGIC_KEY = 2


"""
This is the legacy implementation of Byron addresses. Byron
addresses should however remain supported in Shelley with
exactly the same implementation, thus it is kept here
with base58 encoding and all the nuances of Byron addresses.
"""


def _encode_raw(address_data_encoded: bytes) -> bytes:
    return cbor.encode(
        [cbor.Tagged(24, address_data_encoded), crc.crc32(address_data_encoded)]
    )


def derive(keychain: seed.Keychain, path: list, protocol_magic: int) -> bytes:
    address_attributes = get_address_attributes(protocol_magic)

    address_root = _get_address_root(keychain, path, address_attributes)
    address_type = 0
    address_data = [address_root, address_attributes, address_type]
    address_data_encoded = cbor.encode(address_data)

    return _encode_raw(address_data_encoded)


def get_address_attributes(protocol_magic: int) -> dict:
    # protocol magic is included in Byron addresses only on testnets
    if protocol_magics.is_mainnet(protocol_magic):
        address_attributes = {}
    else:
        address_attributes = {PROTOCOL_MAGIC_KEY: cbor.encode(protocol_magic)}

    return address_attributes


def validate(address: bytes, protocol_magic: int) -> None:
    address_data_encoded = _decode_raw(address)
    _validate_protocol_magic(address_data_encoded, protocol_magic)


def _decode_raw(address: bytes) -> bytes:
    try:
        address_unpacked = cbor.decode(address)
    except ValueError as e:
        if __debug__:
            log.exception(__name__, e)
        raise wire.ProcessError("Invalid address")

    if not isinstance(address_unpacked, list) or len(address_unpacked) != 2:
        raise wire.ProcessError("Invalid address")

    address_data_encoded = address_unpacked[0]
    if not isinstance(address_data_encoded, bytes):
        raise wire.ProcessError("Invalid address")

    address_crc = address_unpacked[1]
    if not isinstance(address_crc, int):
        raise wire.ProcessError("Invalid address")

    if address_crc != crc.crc32(address_data_encoded):
        raise wire.ProcessError("Invalid address")

    return address_data_encoded


def _validate_protocol_magic(address_data_encoded: bytes, protocol_magic: int) -> None:
    """
    Determines whether the correct protocol magic (or none)
    is included in the address. Addresses on mainnet don't
    contain protocol magic, but addresses on the testnet do.
    """
    address_data = cbor.decode(address_data_encoded)
    if not isinstance(address_data, list) or len(address_data) < 2:
        raise wire.ProcessError("Invalid address")

    attributes = address_data[1]
    if protocol_magics.is_mainnet(protocol_magic):
        if PROTOCOL_MAGIC_KEY in attributes:
            raise wire.ProcessError("Output address network mismatch")
    else:  # testnet
        if len(attributes) == 0 or PROTOCOL_MAGIC_KEY not in attributes:
            raise wire.ProcessError("Output address network mismatch")

        protocol_magic_cbor = attributes[PROTOCOL_MAGIC_KEY]
        address_protocol_magic = cbor.decode(protocol_magic_cbor)

        if not isinstance(address_protocol_magic, int):
            raise wire.ProcessError("Invalid address")

        if address_protocol_magic != protocol_magic:
            raise wire.ProcessError("Output address network mismatch")


def _address_hash(data: list) -> bytes:
    cbor_data = cbor.encode(data)
    sha_data_hash = hashlib.sha3_256(cbor_data).digest()
    res = hashlib.blake2b(data=sha_data_hash, outlen=28).digest()
    return res


def _get_address_root(
    keychain: seed.Keychain, path: list[int], address_attributes: dict
) -> bytes:
    extpubkey = derive_public_key(keychain, path, extended=True)
    return _address_hash([0, [0, extpubkey], address_attributes])