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Merge pull request #774 from trezor/tsusanka/shamir-word-checks

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Recovery: refactor word checks and add a test
This commit is contained in:
Tomas Susanka 2019-12-30 13:26:07 +01:00 committed by GitHub
commit ffea791658
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3 changed files with 167 additions and 78 deletions
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92
core/src/apps/management/recovery_device/layout.py
View File

@ -1,13 +1,14 @@
import storage.recovery
from trezor import ui, wire
from trezor.crypto.slip39 import MAX_SHARE_COUNT
from trezor.messages import BackupType, ButtonRequestType
from trezor.messages import ButtonRequestType
from trezor.messages.ButtonAck import ButtonAck
from trezor.messages.ButtonRequest import ButtonRequest
from trezor.ui.scroll import Paginated
from trezor.ui.text import Text
from trezor.ui.word_select import WordSelector
from . import word_validity
from .keyboard_bip39 import Bip39Keyboard
from .keyboard_slip39 import Slip39Keyboard
from .recover import RecoveryAborted
@ -15,7 +16,6 @@ from .recover import RecoveryAborted
from apps.common.confirm import confirm, info_confirm, require_confirm
from apps.common.layout import show_success, show_warning
from apps.management import backup_types
from apps.management.recovery_device import recover
if __debug__:
from apps.debug import input_signal
@ -72,87 +72,23 @@ async def request_mnemonic(
else:
word = await ctx.wait(keyboard)
if not await check_word_validity(ctx, i, word, backup_type, words):
return None
words.append(word)
try:
word_validity.check(backup_type, words)
except word_validity.AlreadyAdded:
await show_share_already_added(ctx)
return None
except word_validity.IdentifierMismatch:
await show_identifier_mismatch(ctx)
return None
except word_validity.ThresholdReached:
await show_group_threshold_reached(ctx)
return None
return " ".join(words)
async def check_word_validity(
ctx: wire.GenericContext,
current_index: int,
current_word: str,
backup_type: Optional[EnumTypeBackupType],
previous_words: List[str],
) -> bool:
# we can't perform any checks if the backup type was not yet decided
if backup_type is None:
return True
# there are no "on-the-fly" checks for BIP-39
if backup_type is BackupType.Bip39:
return True
previous_mnemonics = recover.fetch_previous_mnemonics()
if previous_mnemonics is None:
# this should not happen if backup_type is set
raise RuntimeError
if backup_type == BackupType.Slip39_Basic:
# check if first 3 words of mnemonic match
# we can check against the first one, others were checked already
if current_index < 3:
share_list = previous_mnemonics[0][0].split(" ")
if share_list[current_index] != current_word:
await show_identifier_mismatch(ctx)
return False
elif current_index == 3:
for share in previous_mnemonics[0]:
share_list = share.split(" ")
# check if the fourth word is different from previous shares
if share_list[current_index] == current_word:
await show_share_already_added(ctx)
return False
elif backup_type == BackupType.Slip39_Advanced:
if current_index < 2:
share_list = next(s for s in previous_mnemonics if s)[0].split(" ")
if share_list[current_index] != current_word:
await show_identifier_mismatch(ctx)
return False
# check if we reached threshold in group
elif current_index == 2:
for i, group in enumerate(previous_mnemonics):
if len(group) > 0:
if current_word == group[0].split(" ")[current_index]:
remaining_shares = (
storage.recovery.fetch_slip39_remaining_shares()
)
# if backup_type is not None, some share was already entered -> remaining needs to be set
assert remaining_shares is not None
if remaining_shares[i] == 0:
await show_group_threshold_reached(ctx)
return False
# check if share was already added for group
elif current_index == 3:
# we use the 3rd word from previously entered shares to find the group id
group_identifier_word = previous_words[2]
group_index = None
for i, group in enumerate(previous_mnemonics):
if len(group) > 0:
if group_identifier_word == group[0].split(" ")[2]:
group_index = i
if group_index is not None:
group = previous_mnemonics[group_index]
for share in group:
if current_word == share.split(" ")[current_index]:
await show_share_already_added(ctx)
return False
return True
async def show_remaining_shares(
ctx: wire.GenericContext,
groups: Iterable[Tuple[int, Tuple[str, ...]]], # remaining + list 3 words

105
core/src/apps/management/recovery_device/word_validity.py Normal file
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@ -0,0 +1,105 @@
import storage.recovery
from trezor.messages import BackupType
from apps.management.recovery_device import recover
if False:
from typing import List, Optional
from trezor.messages.ResetDevice import EnumTypeBackupType
class WordValidityResult(Exception):
pass
class IdentifierMismatch(WordValidityResult):
pass
class AlreadyAdded(WordValidityResult):
pass
class ThresholdReached(WordValidityResult):
pass
def check(
backup_type: Optional[EnumTypeBackupType], partial_mnemonic: List[str]
) -> None:
# we can't perform any checks if the backup type was not yet decided
if backup_type is None:
return
# there are no "on-the-fly" checks for BIP-39
if backup_type is BackupType.Bip39:
return
previous_mnemonics = recover.fetch_previous_mnemonics()
if previous_mnemonics is None:
# this should not happen if backup_type is set
raise RuntimeError
if backup_type == BackupType.Slip39_Basic:
check_slip39_basic(partial_mnemonic, previous_mnemonics)
elif backup_type == BackupType.Slip39_Advanced:
check_slip39_advanced(partial_mnemonic, previous_mnemonics)
else:
# there are no other backup types
raise RuntimeError
def check_slip39_basic(
partial_mnemonic: List[str], previous_mnemonics: List[List[str]]
) -> None:
# check if first 3 words of mnemonic match
# we can check against the first one, others were checked already
current_index = len(partial_mnemonic) - 1
current_word = partial_mnemonic[-1]
if current_index < 3:
share_list = previous_mnemonics[0][0].split(" ")
if share_list[current_index] != current_word:
raise IdentifierMismatch
elif current_index == 3:
for share in previous_mnemonics[0]:
share_list = share.split(" ")
# check if the fourth word is different from previous shares
if share_list[current_index] == current_word:
raise AlreadyAdded
def check_slip39_advanced(
partial_mnemonic: List[str], previous_mnemonics: List[List[str]]
) -> None:
current_index = len(partial_mnemonic) - 1
current_word = partial_mnemonic[-1]
if current_index < 2:
share_list = next(s for s in previous_mnemonics if s)[0].split(" ")
if share_list[current_index] != current_word:
raise IdentifierMismatch
# check if we reached threshold in group
elif current_index == 2:
for i, group in enumerate(previous_mnemonics):
if len(group) > 0:
if current_word == group[0].split(" ")[current_index]:
remaining_shares = storage.recovery.fetch_slip39_remaining_shares()
# if backup_type is not None, some share was already entered -> remaining needs to be set
assert remaining_shares is not None
if remaining_shares[i] == 0:
raise ThresholdReached
# check if share was already added for group
elif current_index == 3:
# we use the 3rd word from previously entered shares to find the group id
group_identifier_word = partial_mnemonic[2]
group_index = None
for i, group in enumerate(previous_mnemonics):
if len(group) > 0:
if group_identifier_word == group[0].split(" ")[2]:
group_index = i
if group_index is not None:
group = previous_mnemonics[group_index]
for share in group:
if current_word == share.split(" ")[current_index]:
raise AlreadyAdded

48
core/tests/test_apps.management.recovery_device.py
View File

@ -4,6 +4,8 @@ from mock_storage import mock_storage
import storage
import storage.recovery
from apps.management.recovery_device.recover import process_slip39
from trezor.messages import BackupType
from apps.management.recovery_device.word_validity import check, IdentifierMismatch, AlreadyAdded, ThresholdReached
MNEMONIC_SLIP39_BASIC_20_3of6 = [
"extra extend academic bishop cricket bundle tofu goat apart victim enlarge program behavior permit course armed jerky faint language modern",
@ -140,6 +142,52 @@ class TestSlip39(unittest.TestCase):
secret, share = process_slip39(words)
self.assertIsNone(secret)
@mock_storage
def test_check_word_validity(self):
storage.recovery.set_in_progress(True)
# We claim to know the backup type, but nothing is stored. That is an invalid state.
with self.assertRaises(RuntimeError):
check(BackupType.Slip39_Advanced, ["ocean"])
# if backup type is not set we can not do any checks
check(None, ["ocean"])
# BIP-39 has no "on-the-fly" checks
check(BackupType.Bip39, ["ocean"])
# let's store two shares in the storage
secret, share = process_slip39("trash smug adjust ambition criminal prisoner security math cover pecan response pharmacy center criminal salary elbow bracelet lunar briefing dragon")
self.assertIsNone(secret)
secret, share = process_slip39("trash smug adjust aide benefit temple round clogs devote prevent type cards clogs plastic aspect paper behavior lunar custody intimate")
self.assertIsNone(secret)
# different identifier
with self.assertRaises(IdentifierMismatch):
check(BackupType.Slip39_Advanced, ["slush"])
# same first word but still a different identifier
with self.assertRaises(IdentifierMismatch):
check(BackupType.Slip39_Advanced, ["trash", "slush"])
# same identifier but different group settings for Slip 39 Basic
with self.assertRaises(IdentifierMismatch):
check(BackupType.Slip39_Basic, ["trash", "smug", "slush"])
# same mnemonic found out using the index
with self.assertRaises(AlreadyAdded):
check(BackupType.Slip39_Advanced, ["trash", "smug", "adjust", "ambition"])
# Let's store two more. The group is 4/6 so this group is now complete.
secret, share = process_slip39("trash smug adjust arena beard quick language program true hush amount round geology should training practice language diet order ruin")
self.assertIsNone(secret)
secret, share = process_slip39("trash smug adjust beam brave sack magazine radar toxic emission domestic cradle vocal petition mule toxic acid hobo welcome downtown")
self.assertIsNone(secret)
# If trying to add another one from this group we get a warning.
with self.assertRaises(ThresholdReached):
check(BackupType.Slip39_Advanced, ["trash", "smug", "adjust"])
if __name__ == "__main__":
unittest.main()