trezor-firmware/core/src/apps/ethereum/get_public_key.py

from typing import TYPE_CHECKING
from ubinascii import hexlify

from trezor.messages import EthereumPublicKey, HDNodeType
from trezor.ui.layouts import show_pubkey

from apps.common import coins, paths

from .keychain import with_keychain_from_path

if TYPE_CHECKING:
    from trezor.messages import EthereumGetPublicKey
    from trezor.wire import Context

    from apps.common.keychain import Keychain


@with_keychain_from_path(paths.PATTERN_BIP44_PUBKEY)
async def get_public_key(
    ctx: Context, msg: EthereumGetPublicKey, keychain: Keychain
) -> EthereumPublicKey:
    await paths.validate_path(ctx, keychain, msg.address_n)
    node = keychain.derive(msg.address_n)

    # we use the Bitcoin format for Ethereum xpubs
    btc = coins.by_name("Bitcoin")
    node_xpub = node.serialize_public(btc.xpub_magic)

    pubkey = node.public_key()
    if pubkey[0] == 1:
        pubkey = b"\x00" + pubkey[1:]
    node_type = HDNodeType(
        depth=node.depth(),
        child_num=node.child_num(),
        fingerprint=node.fingerprint(),
        chain_code=node.chain_code(),
        public_key=pubkey,
    )

    if msg.show_display:
        await show_pubkey(ctx, hexlify(pubkey).decode())

    return EthereumPublicKey(node=node_type, xpub=node_xpub)