mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-12-04 21:48:17 +00:00
375 lines
13 KiB
Python
375 lines
13 KiB
Python
from micropython import const
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from typing import TYPE_CHECKING
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HARDENED = const(0x8000_0000)
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SLIP25_PURPOSE = const(10025 | HARDENED)
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if TYPE_CHECKING:
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from typing import (
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Any,
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Callable,
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Collection,
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Container,
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Iterable,
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Sequence,
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TypeVar,
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)
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from typing_extensions import Protocol
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from trezor import wire
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Bip32Path = Sequence[int]
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Slip21Path = Sequence[bytes]
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PathType = TypeVar("PathType", Bip32Path, Slip21Path, contravariant=True)
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class PathSchemaType(Protocol):
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def match(self, path: Bip32Path) -> bool:
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...
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class KeychainValidatorType(Protocol):
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def is_in_keychain(self, path: Bip32Path) -> bool:
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...
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def verify_path(self, path: Bip32Path) -> None:
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...
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class Interval:
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"""Helper for testing membership in an interval."""
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def __init__(self, min: int, max: int) -> None:
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self.min = min
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self.max = max
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def __contains__(self, x: object) -> bool:
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if not isinstance(x, int):
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return False
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return self.min <= x <= self.max
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class PathSchema:
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"""General BIP-32 path schema.
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Loosely based on the BIP-32 path template proposal [1].
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Each path component can be one of the following:
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- constant, e.g., `7`
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- list of constants, e.g., `[1,2,3]`
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- range, e.g., `[0-19]`
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Brackets are recommended but not enforced.
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The following substitutions are available:
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- `coin_type` is substituted with the coin's SLIP-44 identifier
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- `account` is substituted with `[0-100]`, Trezor's default range of accounts
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- `change` is substituted with `[0,1]`
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- `address_index` is substituted with `[0-1000000]`, Trezor's default range of
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addresses
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Hardened flag is indicated by an apostrophe and applies to the whole path component.
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It is impossible to specify both hardened and non-hardened values for the same
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component.
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See examples of valid path formats below and in `apps.bitcoin.keychain`.
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E.g. the following are equivalent definitions of a BIP-84 schema:
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m/84'/coin_type'/[0-100]'/[0,1]/[0-1000000]
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m/84'/coin_type'/0-100'/0,1/0-1000000
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m/84'/coin_type'/account'/change/address_index
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Adding an asterisk at the end of the pattern acts as a wildcard for zero or more
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path components:
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- m/* can be followed by any number of _unhardened_ path components
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- m/*' can be followed by any number of _hardened_ path components
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- m/** can be followed by any number of _any_ path components
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The following is a BIP-44 generic `GetPublicKey` schema:
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m/44'/coin_type'/account'/*
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The asterisk expression can only appear at end of pattern.
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[1] https://github.com/dgpv/bip32_template_parse_tplaplus_spec/blob/master/bip-path-templates.mediawiki
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"""
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REPLACEMENTS = {
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"account": "0-100",
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"change": "0,1",
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"address_index": "0-1000000",
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}
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WILDCARD_RANGES = {
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"*": Interval(0, HARDENED - 1),
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"*'": Interval(HARDENED, 0xFFFF_FFFF),
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"**": Interval(0, 0xFFFF_FFFF),
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}
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_EMPTY_TUPLE = ()
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@staticmethod
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def _parse_hardened(s: str | int) -> int:
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return int(s) | HARDENED
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@staticmethod
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def _copy_container(container: Container[int]) -> Container[int]:
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# On hardware, hardened indices do not fit into smallint.
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# The n+0 operation ensures that a new instance of a longint is created.
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if isinstance(container, Interval):
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return Interval(container.min + 0, container.max + 0)
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if isinstance(container, set):
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return set(i + 0 for i in container)
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if isinstance(container, tuple):
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return tuple(i + 0 for i in container)
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raise RuntimeError("Unsupported container for copy")
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def __init__(
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self,
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schema: list[Container[int]],
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trailing_components: Container[int] = (),
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compact: bool = False,
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) -> None:
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"""Create a new PathSchema from a list of containers and trailing components.
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Mainly for internal use in `PathSchema.parse`, which is the method you should
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be using.
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Can be used to create a schema manually without parsing a path string:
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>>> SCHEMA_MINE = PathSchema([
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>>> (44 | HARDENED,),
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>>> (0 | HARDENED,),
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>>> Interval(0 | HARDENED, 10 | HARDENED),
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>>> ],
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>>> trailing_components=Interval(0, 0xFFFF_FFFF),
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>>> )
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Setting `compact=True` creates a compact copy of the provided components, so
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as to prevent memory fragmentation.
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"""
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if compact:
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self.schema: list[Container[int]] = [self._EMPTY_TUPLE] * len(schema)
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for i in range(len(schema)):
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self.schema[i] = self._copy_container(schema[i])
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self.trailing_components = self._copy_container(trailing_components)
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else:
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self.schema = schema
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self.trailing_components = trailing_components
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@classmethod
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def parse(cls, pattern: str, slip44_id: int | Iterable[int]) -> "PathSchema":
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"""Parse a path schema string into a PathSchema instance.
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The parsing process trashes the memory layout, so at the end a compact-allocated
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copy of the resulting structures is returned.
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"""
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if not pattern.startswith("m/"):
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raise ValueError # unsupported path template
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components = pattern[2:].split("/")
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if isinstance(slip44_id, int):
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slip44_id = (slip44_id,)
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schema: list[Container[int]] = []
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trailing_components: Container[int] = ()
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for component in components:
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if component in cls.WILDCARD_RANGES:
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if len(schema) != len(components) - 1:
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# every component should have resulted in extending schema
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# so if schema does not have the appropriate length (yet),
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# the asterisk is not the last item
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raise ValueError # asterisk is not last item of pattern
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trailing_components = cls.WILDCARD_RANGES[component]
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break
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# figure out if the component is hardened
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if component[-1] == "'":
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component = component[:-1]
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parse: Callable[[Any], int] = cls._parse_hardened
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else:
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parse = int
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# strip brackets
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if component[0] == "[" and component[-1] == "]":
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component = component[1:-1]
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# optionally replace a keyword
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component = cls.REPLACEMENTS.get(component, component)
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if "-" in component:
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# parse as a range
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a, b = [parse(s) for s in component.split("-", 1)]
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schema.append(Interval(a, b))
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elif "," in component:
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# parse as a list of values
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schema.append(set(parse(s) for s in component.split(",")))
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elif component == "coin_type":
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# substitute SLIP-44 ids
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schema.append(set(parse(s) for s in slip44_id))
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else:
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# plain constant
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schema.append((parse(component),))
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return cls(schema, trailing_components, compact=True)
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def copy(self) -> "PathSchema":
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"""Create a compact copy of the schema.
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Useful when creating multiple schemas in a row. The following code ensures
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that the set of schemas is allocated in a contiguous block of memory:
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>>> some_schemas = make_multiple_schemas()
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>>> some_schemas = [s.copy() for s in some_schemas]
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"""
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return PathSchema(self.schema, self.trailing_components, compact=True)
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def match(self, path: Bip32Path) -> bool:
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# The path must not be _shorter_ than schema. It may be longer.
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if len(path) < len(self.schema):
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return False
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path_iter = iter(path)
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# iterate over length of schema, consuming path components
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for expected in self.schema:
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value = next(path_iter)
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if value not in expected:
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return False
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# iterate over remaining path components
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for value in path_iter:
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if value not in self.trailing_components:
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return False
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return True
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def set_never_matching(self) -> None:
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"""Sets the schema to never match any paths."""
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self.schema = []
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self.trailing_components = self._EMPTY_TUPLE
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def restrict(self, path: Bip32Path) -> bool:
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"""
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Restricts the schema to patterns that are prefixed by the specified
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path. If the restriction results in a never-matching schema, then False
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is returned.
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"""
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for i, value in enumerate(path):
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if i < len(self.schema):
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# Ensure that the path is a prefix of the schema.
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if value not in self.schema[i]:
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self.set_never_matching()
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return False
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# Restrict the schema component if there are multiple choices.
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component = self.schema[i]
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if not isinstance(component, tuple) or len(component) != 1:
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self.schema[i] = (value,)
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else:
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# The path is longer than the schema. We need to restrict the
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# trailing components.
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if value not in self.trailing_components:
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self.set_never_matching()
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return False
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self.schema.append((value,))
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return True
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if __debug__:
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def __repr__(self) -> str:
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components = ["m"]
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def unharden(item: int) -> int:
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return item ^ (item & HARDENED)
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for component in self.schema:
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if isinstance(component, Interval):
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a, b = component.min, component.max
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prime = "'" if a & HARDENED else ""
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components.append(f"[{unharden(a)}-{unharden(b)}]{prime}")
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else:
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# typechecker thinks component is a Contanier but we're using it
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# as a Collection.
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# Which in practice it is, the only non-Collection is Interval.
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# But we're not going to introduce an additional type requirement
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# for the sake of __repr__ that doesn't exist in production anyway
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collection: Collection[int] = component # type: ignore [Expression of type "Container[int]" cannot be assigned to declared type "Collection[int]"]
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component_str = ",".join(str(unharden(i)) for i in collection)
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if len(collection) > 1:
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component_str = "[" + component_str + "]"
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if next(iter(collection)) & HARDENED:
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component_str += "'"
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components.append(component_str)
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if self.trailing_components:
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for key, val in self.WILDCARD_RANGES.items():
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if self.trailing_components is val:
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components.append(key)
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break
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else:
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components.append("???")
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return "<schema:" + "/".join(components) + ">"
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class AlwaysMatchingSchema:
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@staticmethod
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def match(path: Bip32Path) -> bool:
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return True
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# BIP-44 for basic (legacy) Bitcoin accounts, and widely used for other currencies:
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# https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki
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PATTERN_BIP44 = "m/44'/coin_type'/account'/change/address_index"
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# BIP-44 public key export, starting at end of the hardened part
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PATTERN_BIP44_PUBKEY = "m/44'/coin_type'/account'/*"
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# SEP-0005 for non-UTXO-based currencies, defined by Stellar:
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# https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0005.md
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PATTERN_SEP5 = "m/44'/coin_type'/account'"
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async def validate_path(
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ctx: wire.Context,
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keychain: KeychainValidatorType,
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path: Bip32Path,
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*additional_checks: bool,
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) -> None:
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keychain.verify_path(path)
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if not keychain.is_in_keychain(path) or not all(additional_checks):
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await show_path_warning(ctx, path)
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async def show_path_warning(ctx: wire.Context, path: Bip32Path) -> None:
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from trezor.ui.layouts import confirm_path_warning
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await confirm_path_warning(ctx, address_n_to_str(path))
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def is_hardened(i: int) -> bool:
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return bool(i & HARDENED)
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def path_is_hardened(address_n: Bip32Path) -> bool:
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return all(is_hardened(n) for n in address_n)
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def address_n_to_str(address_n: Iterable[int]) -> str:
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def path_item(i: int) -> str:
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if i & HARDENED:
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return str(i ^ HARDENED) + "'"
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else:
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return str(i)
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if not address_n:
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return "m"
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return "m/" + "/".join(path_item(i) for i in address_n)
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