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

from trezor import wire
from trezor.crypto import bip32
from trezor.crypto.hashlib import sha256
from trezor.messages.HDNodeType import HDNodeType
from trezor.messages.MultisigRedeemScriptType import MultisigRedeemScriptType
from trezor.utils import HashWriter

from apps.common import paths

from .writers import write_bytes_fixed, write_uint32


def multisig_fingerprint(multisig: MultisigRedeemScriptType) -> bytes:
    if multisig.nodes:
        pubnodes = multisig.nodes
    else:
        pubnodes = [hd.node for hd in multisig.pubkeys]
    m = multisig.m
    n = len(pubnodes)

    if n < 1 or n > 15 or m < 1 or m > 15:
        raise wire.DataError("Invalid multisig parameters")

    for d in pubnodes:
        if len(d.public_key) != 33 or len(d.chain_code) != 32:
            raise wire.DataError("Invalid multisig parameters")

    # casting to bytes(), sorting on bytearray() is not supported in MicroPython
    pubnodes = sorted(pubnodes, key=lambda n: bytes(n.public_key))

    h = HashWriter(sha256())
    write_uint32(h, m)
    write_uint32(h, n)
    for d in pubnodes:
        write_uint32(h, d.depth)
        write_uint32(h, d.fingerprint)
        write_uint32(h, d.child_num)
        write_bytes_fixed(h, d.chain_code, 32)
        write_bytes_fixed(h, d.public_key, 33)

    return h.get_digest()


def validate_multisig(multisig: MultisigRedeemScriptType) -> None:
    if any(paths.is_hardened(n) for n in multisig.address_n):
        raise wire.DataError("Cannot perform hardened derivation from XPUB")
    for hd in multisig.pubkeys:
        if any(paths.is_hardened(n) for n in hd.address_n):
            raise wire.DataError("Cannot perform hardened derivation from XPUB")


def multisig_pubkey_index(multisig: MultisigRedeemScriptType, pubkey: bytes) -> int:
    validate_multisig(multisig)
    if multisig.nodes:
        for i, hd_node in enumerate(multisig.nodes):
            if multisig_get_pubkey(hd_node, multisig.address_n) == pubkey:
                return i
    else:
        for i, hd in enumerate(multisig.pubkeys):
            if multisig_get_pubkey(hd.node, hd.address_n) == pubkey:
                return i
    raise wire.DataError("Pubkey not found in multisig script")


def multisig_get_pubkey(n: HDNodeType, p: paths.Bip32Path) -> bytes:
    node = bip32.HDNode(
        depth=n.depth,
        fingerprint=n.fingerprint,
        child_num=n.child_num,
        chain_code=n.chain_code,
        public_key=n.public_key,
    )
    for i in p:
        node.derive(i, True)
    return node.public_key()


def multisig_get_pubkeys(multisig: MultisigRedeemScriptType) -> list[bytes]:
    validate_multisig(multisig)
    if multisig.nodes:
        return [multisig_get_pubkey(hd, multisig.address_n) for hd in multisig.nodes]
    else:
        return [multisig_get_pubkey(hd.node, hd.address_n) for hd in multisig.pubkeys]


def multisig_get_pubkey_count(multisig: MultisigRedeemScriptType) -> int:
    if multisig.nodes:
        return len(multisig.nodes)
    else:
        return len(multisig.pubkeys)