# Copyright (c) 2020 Yubico AB
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# without modification, are permitted provided that the following
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import logging
import struct
from threading import Event
from typing import Callable, Iterator, Optional
from fido2.ctap import STATUS, CtapDevice, CtapError
from fido2.hid import CAPABILITY, CTAPHID
from yubikit.core import Version
from yubikit.core.smartcard import (
AID,
ApduError,
SmartCardConnection,
SmartCardProtocol,
)
from yubikit.core.smartcard.scp import ScpKeyParams
from . import USB_INTERFACE, Connection
logger = logging.getLogger(__name__)
# Make CtapDevice a Connection
FidoConnection = CtapDevice
FidoConnection.usb_interface = USB_INTERFACE.FIDO # type: ignore[attr-defined]
Connection.register(FidoConnection)
# Use SmartCardConnection for FIDO access, allowing usage of SCP
[docs]
class SmartCardCtapDevice(CtapDevice):
def __init__(
self,
connection: SmartCardConnection,
scp_key_params: Optional[ScpKeyParams] = None,
):
self._capabilities = CAPABILITY(0)
self.protocol = SmartCardProtocol(connection)
resp = self.protocol.select(AID.FIDO)
if resp == b"U2F_V2":
self._capabilities |= CAPABILITY.NMSG
if scp_key_params:
# We can at least raise the configuration level to 5.3.0, since SCP is not available before then
self.protocol.configure(Version(5, 3, 0))
self.protocol.init_scp(scp_key_params)
try: # Probe for CTAP2 by calling GET_INFO
self.call(CTAPHID.CBOR, b"\x04")
self._capabilities |= CAPABILITY.CBOR
except CtapError:
if not self._capabilities:
raise ValueError("Unsupported device")
logger.debug("FIDO session initialized")
@property
def capabilities(self) -> CAPABILITY:
return self._capabilities
[docs]
def close(self) -> None:
self.protocol.close()
[docs]
def call(
self,
cmd: int,
data: bytes = b"",
event: Optional[Event] = None,
on_keepalive: Optional[Callable[[STATUS], None]] = None,
) -> bytes:
if cmd == CTAPHID.MSG:
cla, ins, p1, p2 = data[:4]
if data[4] == 0:
ln = struct.unpack(">H", data[5:7])[0]
data = data[7 : 7 + ln]
else:
data = data[5 : 5 + data[4]]
elif cmd == CTAPHID.CBOR:
# NFCCTAP_MSG
cla, ins, p1, p2 = 0x80, 0x10, 0x00, 0x00
else:
raise CtapError(CtapError.ERR.INVALID_COMMAND)
try:
return self.protocol.send_apdu(cla, ins, p1, p2, data)
except ApduError:
raise CtapError(CtapError.ERR.OTHER) # TODO: Map from SW error
[docs]
@classmethod
def list_devices(cls) -> Iterator[CtapDevice]:
return iter([]) # Not implemented