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trezor-firmware/core/src/apps/misc/cosi_commit.py

115 lines
3.9 KiB

from typing import TYPE_CHECKING
from trezor.enums import ButtonRequestType
from trezor.messages import CosiCommitment, CosiSign, CosiSignature
from trezor.wire import DataError
from apps.common.paths import PathSchema, unharden
if TYPE_CHECKING:
from trezor.messages import CosiCommit
# This module implements the cosigner part of the CoSi collective signatures
# as described in https://dedis.cs.yale.edu/dissent/papers/witness.pdf
SCHEMA_SLIP18 = PathSchema.parse("m/10018'/address_index'/*'", slip44_id=())
# SLIP-26: m/10026'/model'/type'/rotation_index'
# - `model`: typically ASCII string T1B1 etc. parsed as little-endian number,
# but can also be 0 or other values. Maximum allowed value is 0x7F7F7F7F,
# the maximum 4-byte ASCII string.
# - `type`: 0 = bootloader, 1 = vendorheader, 2 = firmware, 3 = definitions, 4 = reserved
# - `rotation_index`: a fixed 0' for now
SCHEMA_SLIP26 = PathSchema.parse("m/10026'/[0-2139062143]'/[0-4]'/0'", slip44_id=())
def _decode_path(address_n: list[int]) -> str | None:
signing_types = {
0: "bootloader",
1: "vendor header",
2: "firmware",
}
if len(address_n) == 2 and SCHEMA_SLIP18.match(address_n):
signing_type = signing_types.get(unharden(address_n[1]))
if signing_type is None:
return None
return f"T2T1 {signing_type} (old-style)"
if SCHEMA_SLIP26.match(address_n):
model = unharden(address_n[1])
signing_type = unharden(address_n[2])
if model == 0 and signing_type == 3:
return "External definitions"
model_bytes = model.to_bytes(4, "little")
signing_type_str = signing_types.get(signing_type)
if (
signing_type_str is not None
and len(model_bytes) == 4
and all(0x20 <= b <= 0x7E for b in model_bytes)
):
return f"{model_bytes.decode()} {signing_type_str}"
return None
async def cosi_commit(msg: CosiCommit) -> CosiSignature:
import storage.cache as storage_cache
from trezor.crypto import cosi
from trezor.crypto.curve import ed25519
from trezor.ui.layouts import confirm_blob, confirm_text
from trezor.wire import context
from trezor.wire.context import call
from apps.common import paths
from apps.common.keychain import get_keychain
keychain = await get_keychain("ed25519", [SCHEMA_SLIP18, SCHEMA_SLIP26])
await paths.validate_path(keychain, msg.address_n)
node = keychain.derive(msg.address_n)
seckey = node.private_key()
pubkey = ed25519.publickey(seckey)
if not context.cache_is_set(storage_cache.APP_MISC_COSI_COMMITMENT):
nonce, commitment = cosi.commit()
context.cache_set(storage_cache.APP_MISC_COSI_NONCE, nonce)
context.cache_set(storage_cache.APP_MISC_COSI_COMMITMENT, commitment)
commitment = context.cache_get(storage_cache.APP_MISC_COSI_COMMITMENT)
if commitment is None:
raise RuntimeError
sign_msg = await call(
CosiCommitment(commitment=commitment, pubkey=pubkey), CosiSign
)
if sign_msg.address_n != msg.address_n:
raise DataError("Mismatched address_n")
path_description = _decode_path(sign_msg.address_n)
await confirm_text(
"cosi_confirm_key",
"COSI KEYS",
paths.address_n_to_str(sign_msg.address_n),
path_description,
)
await confirm_blob(
"cosi_sign",
"COSI DATA",
sign_msg.data,
br_code=ButtonRequestType.ProtectCall,
)
# clear nonce from cache
nonce = context.cache_get(storage_cache.APP_MISC_COSI_NONCE)
storage_cache.delete(storage_cache.APP_MISC_COSI_COMMITMENT)
storage_cache.delete(storage_cache.APP_MISC_COSI_NONCE)
if nonce is None:
raise RuntimeError
signature = cosi.sign(
seckey, sign_msg.data, nonce, sign_msg.global_commitment, sign_msg.global_pubkey
)
return CosiSignature(signature=signature)