# Copyright (c) 2018 Yubico AB # All rights reserved. # # Redistribution and use in source and binary forms, with or # without modification, are permitted provided that the following # conditions are met: # # 1. Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # 2. Redistributions in binary form must reproduce the above # copyright notice, this list of conditions and the following # disclaimer in the documentation and/or other materials provided # with the distribution. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. from .hid import STATUS from .ctap import CtapDevice, CtapError from .ctap1 import Ctap1, APDU, ApduError from .ctap2 import Ctap2, AssertionResponse, Info from .ctap2.pin import ClientPin from .ctap2.extensions import Ctap2Extension from .webauthn import ( AttestationObject, PublicKeyCredentialCreationOptions, PublicKeyCredentialRequestOptions, AuthenticatorSelectionCriteria, UserVerificationRequirement, AuthenticatorAttestationResponse, AuthenticatorAssertionResponse, ) from .cose import ES256 from .rpid import verify_rp_id, verify_app_id from .utils import sha256, websafe_decode, websafe_encode from enum import Enum, IntEnum, unique from threading import Timer, Event from typing import Type, Any, Union, Callable, Optional, Mapping, Sequence import json import platform import inspect class ClientData(bytes): def __init__(self, _): super(ClientData, self).__init__() self._data = json.loads(self.decode()) def get(self, key: str) -> Any: return self._data[key] @property def challenge(self) -> bytes: return websafe_decode(self.get("challenge")) @property def b64(self) -> str: return websafe_encode(self) @property def hash(self) -> bytes: return sha256(self) @classmethod def build(cls, **kwargs) -> "ClientData": return cls(json.dumps(kwargs).encode()) @classmethod def from_b64(cls, data: Union[str, bytes]) -> "ClientData": return cls(websafe_decode(data)) def __repr__(self): return self.decode() def __str__(self): return self.decode() class ClientError(Exception): @unique class ERR(IntEnum): OTHER_ERROR = 1 BAD_REQUEST = 2 CONFIGURATION_UNSUPPORTED = 3 DEVICE_INELIGIBLE = 4 TIMEOUT = 5 def __call__(self, cause=None): return ClientError(self, cause) def __init__(self, code, cause=None): self.code = ClientError.ERR(code) self.cause = cause def __repr__(self): r = "Client error: {0} - {0.name}".format(self.code) if self.cause: r += f" (cause: {self.cause})" return r def _ctap2client_err(e, err_cls=ClientError): if e.code in [CtapError.ERR.CREDENTIAL_EXCLUDED, CtapError.ERR.NO_CREDENTIALS]: ce = ClientError.ERR.DEVICE_INELIGIBLE elif e.code in [ CtapError.ERR.KEEPALIVE_CANCEL, CtapError.ERR.ACTION_TIMEOUT, CtapError.ERR.USER_ACTION_TIMEOUT, ]: ce = ClientError.ERR.TIMEOUT elif e.code in [ CtapError.ERR.UNSUPPORTED_ALGORITHM, CtapError.ERR.UNSUPPORTED_OPTION, CtapError.ERR.KEY_STORE_FULL, ]: ce = ClientError.ERR.CONFIGURATION_UNSUPPORTED elif e.code in [ CtapError.ERR.INVALID_COMMAND, CtapError.ERR.CBOR_UNEXPECTED_TYPE, CtapError.ERR.INVALID_CBOR, CtapError.ERR.MISSING_PARAMETER, CtapError.ERR.INVALID_OPTION, CtapError.ERR.PUAT_REQUIRED, CtapError.ERR.PIN_INVALID, CtapError.ERR.PIN_BLOCKED, CtapError.ERR.PIN_NOT_SET, CtapError.ERR.PIN_POLICY_VIOLATION, CtapError.ERR.PIN_TOKEN_EXPIRED, CtapError.ERR.PIN_AUTH_INVALID, CtapError.ERR.PIN_AUTH_BLOCKED, CtapError.ERR.REQUEST_TOO_LARGE, CtapError.ERR.OPERATION_DENIED, ]: ce = ClientError.ERR.BAD_REQUEST else: ce = ClientError.ERR.OTHER_ERROR return err_cls(ce, e) class PinRequiredError(ClientError): def __init__( self, code=ClientError.ERR.BAD_REQUEST, cause="Pin required but not provided" ): super(PinRequiredError, self).__init__(code, cause) def _call_polling(poll_delay, event, on_keepalive, func, *args, **kwargs): event = event or Event() while not event.is_set(): try: return func(*args, **kwargs) except ApduError as e: if e.code == APDU.USE_NOT_SATISFIED: if on_keepalive: on_keepalive(STATUS.UPNEEDED) on_keepalive = None event.wait(poll_delay) else: raise ClientError.ERR.OTHER_ERROR(e) except CtapError as e: raise _ctap2client_err(e) raise ClientError.ERR.TIMEOUT() @unique class U2F_TYPE(str, Enum): REGISTER = "navigator.id.finishEnrollment" SIGN = "navigator.id.getAssertion" class U2fClient: """U2F-like client implementation. The client allows registration and authentication of U2F credentials against an Authenticator using CTAP 1. Prefer using Fido2Client if possible. :param device: CtapDevice to use. :param str origin: The origin to use. :param verify: Function to verify an APP ID for a given origin. """ def __init__( self, device: CtapDevice, origin: str, verify: Callable[[str, str], bool] = verify_app_id, ): self.poll_delay = 0.25 self.ctap = Ctap1(device) self.origin = origin self._verify = verify def _verify_app_id(self, app_id): try: if self._verify(app_id, self.origin): return except Exception: # nosec pass # Fall through to ClientError raise ClientError.ERR.BAD_REQUEST() def register( self, app_id: str, register_requests: Sequence[Mapping[str, str]], registered_keys: Sequence[Mapping[str, Any]], event: Optional[Event] = None, on_keepalive: Optional[Callable[[int], None]] = None, ) -> Mapping[str, str]: self._verify_app_id(app_id) version = self.ctap.get_version() dummy_param = b"\0" * 32 for key in registered_keys: if key["version"] != version: continue key_app_id = key.get("appId", app_id) app_param = sha256(key_app_id.encode()) self._verify_app_id(key_app_id) key_handle = websafe_decode(key["keyHandle"]) try: self.ctap.authenticate(dummy_param, app_param, key_handle, True) raise ClientError.ERR.DEVICE_INELIGIBLE() # Bad response except ApduError as e: if e.code == APDU.USE_NOT_SATISFIED: raise ClientError.ERR.DEVICE_INELIGIBLE() except CtapError as e: raise _ctap2client_err(e) for request in register_requests: if request["version"] == version: challenge = request["challenge"] break else: raise ClientError.ERR.DEVICE_INELIGIBLE() client_data = ClientData.build( typ=U2F_TYPE.REGISTER, challenge=challenge, origin=self.origin ) app_param = sha256(app_id.encode()) reg_data = _call_polling( self.poll_delay, event, on_keepalive, self.ctap.register, client_data.hash, app_param, ) return {"registrationData": reg_data.b64, "clientData": client_data.b64} def sign( self, app_id: str, challenge: bytes, registered_keys: Sequence[Mapping[str, Any]], event: Optional[Event] = None, on_keepalive: Optional[Callable[[int], None]] = None, ) -> Mapping[str, str]: client_data = ClientData.build( typ=U2F_TYPE.SIGN, challenge=challenge, origin=self.origin ) version = self.ctap.get_version() for key in registered_keys: if key["version"] == version: key_app_id = key.get("appId", app_id) self._verify_app_id(key_app_id) key_handle = websafe_decode(key["keyHandle"]) app_param = sha256(key_app_id.encode()) try: signature_data = _call_polling( self.poll_delay, event, on_keepalive, self.ctap.authenticate, client_data.hash, app_param, key_handle, ) break except ClientError: # nosec pass # Ignore and try next key else: raise ClientError.ERR.DEVICE_INELIGIBLE() return { "clientData": client_data.b64, "signatureData": signature_data.b64, "keyHandle": key["keyHandle"], } @unique class WEBAUTHN_TYPE(str, Enum): MAKE_CREDENTIAL = "webauthn.create" GET_ASSERTION = "webauthn.get" class _BaseClient: def __init__(self, origin: str, verify: Callable[[str, str], bool]): self.origin = origin self._verify = verify def _verify_rp_id(self, rp_id): try: if self._verify(rp_id, self.origin): return except Exception: # nosec pass # Fall through to ClientError raise ClientError.ERR.BAD_REQUEST() def _build_client_data(self, typ, challenge, extensions={}): return ClientData.build( type=typ, origin=self.origin, challenge=websafe_encode(challenge), clientExtensions=extensions, ) class AssertionSelection: """GetAssertion result holding one or more assertions. Since multiple assertions may be retured by Fido2Client.get_assertion, this result is returned which can be used to select a specific response to get. """ def __init__( self, client_data: ClientData, assertions: Sequence[AssertionResponse] ): self._client_data = client_data self._assertions = assertions def get_assertions(self) -> Sequence[AssertionResponse]: """Get the raw AssertionResponses available to inspect before selecting one.""" return self._assertions def _get_extension_results(self, assertion): return {} # Not implemented def get_response(self, index: int) -> AuthenticatorAssertionResponse: """Get a single response.""" assertion = self._assertions[index] return AuthenticatorAssertionResponse( self._client_data, assertion.auth_data, assertion.signature, assertion.user["id"] if assertion.user else None, assertion.credential["id"] if assertion.credential else None, self._get_extension_results(assertion), ) class Fido2ClientAssertionSelection(AssertionSelection): def __init__( self, client_data: ClientData, assertions: Sequence[AssertionResponse], extensions: Sequence[Ctap2Extension], ): super(Fido2ClientAssertionSelection, self).__init__(client_data, assertions) self._extensions = extensions def _get_extension_results(self, assertion): # Process extenstion outputs extension_outputs = {} try: for ext in self._extensions: output = ext.process_get_output(assertion.auth_data) if output is not None: extension_outputs.update(output) except ValueError as e: raise ClientError.ERR.CONFIGURATION_UNSUPPORTED(e) return extension_outputs def _default_extensions() -> Sequence[Type[Ctap2Extension]]: return [ cls for cls in Ctap2Extension.__subclasses__() if not inspect.isabstract(cls) ] _CTAP1_INFO = Info.create(versions=["U2F_V2"], aaguid=b"\0" * 32) class Fido2Client(_BaseClient): """WebAuthn-like client implementation. The client allows registration and authentication of WebAuthn credentials against an Authenticator using CTAP (1 or 2). :param device: CtapDevice to use. :param str origin: The origin to use. :param verify: Function to verify an RP ID for a given origin. """ def __init__( self, device: CtapDevice, origin: str, verify: Callable[[str, str], bool] = verify_rp_id, extension_types: Sequence[Type[Ctap2Extension]] = [], ): super(Fido2Client, self).__init__(origin, verify) self.extensions = extension_types or _default_extensions() self.ctap1_poll_delay = 0.25 try: self.ctap2 = Ctap2(device) self.info = self.ctap2.info try: self.client_pin: ClientPin = ClientPin(self.ctap2) except ValueError: self.client_pin = None # type: ignore self._do_make_credential = self._ctap2_make_credential self._do_get_assertion = self._ctap2_get_assertion except (ValueError, CtapError): self.ctap1 = Ctap1(device) self.info = _CTAP1_INFO self._do_make_credential = self._ctap1_make_credential self._do_get_assertion = self._ctap1_get_assertion def _should_use_uv(self, user_verification, mc): uv_supported = any( k in self.info.options for k in ("uv", "clientPin", "bioEnroll") ) uv_configured = any( self.info.options.get(k) for k in ("uv", "clientPin", "bioEnroll") ) if ( user_verification == UserVerificationRequirement.REQUIRED or ( user_verification == UserVerificationRequirement.PREFERRED and uv_supported ) or self.info.options.get("alwaysUv") ): if not uv_configured: raise ClientError.ERR.CONFIGURATION_UNSUPPORTED( "User verification not configured/supported" ) return True elif mc and uv_configured and not self.info.options.get("makeCredUvNotRqd"): return True return False def _get_token(self, permissions, rp_id, pin, event, on_keepalive): if pin: if self.info.options.get("clientPin"): return self.client_pin.get_pin_token(pin, permissions, rp_id) else: raise ClientError.ERR.BAD_REQUEST("PIN provided, but not set/supported") elif self.info.options.get("uv"): if self.info.options.get("pinUvAuthToken") and self.info.options.get( "bioEnroll" ): try: return self.client_pin.get_uv_token( permissions, rp_id, event, on_keepalive ) except CtapError as e: raise _ctap2client_err(e, PinRequiredError) else: return None # No token, use uv=True elif self.info.options.get("clientPin"): raise PinRequiredError() raise ClientError.ERR.CONFIGURATION_UNSUPPORTED( "User verification not configured/supported" ) def _get_auth_params( self, client_data, rp_id, user_verification, pin, event, on_keepalive ): mc = client_data.get("type") == WEBAUTHN_TYPE.MAKE_CREDENTIAL self.info = self.ctap2.get_info() # Make sure we have "fresh" info pin_auth = None pin_protocol = None internal_uv = False if self._should_use_uv(user_verification, mc): permission = ( ClientPin.PERMISSION.MAKE_CREDENTIAL if mc else ClientPin.PERMISSION.GET_ASSERTION ) token = self._get_token(permission, rp_id, pin, event, on_keepalive) if token: pin_protocol = self.client_pin.protocol.VERSION pin_auth = self.client_pin.protocol.authenticate( token, client_data.hash ) else: internal_uv = True return pin_protocol, pin_auth, internal_uv def make_credential( self, options: PublicKeyCredentialCreationOptions, pin: Optional[str] = None, event: Optional[Event] = None, on_keepalive: Optional[Callable[[int], None]] = None, ): """Creates a credential. :param options: PublicKeyCredentialCreationOptions data. :param pin: (optional) Used if PIN verification is required. :param threading.Event event: (optional) Signal to abort the operation. :param on_keepalive: (optional) function to call with CTAP status updates. """ options = PublicKeyCredentialCreationOptions._wrap(options) event = event or Event() if options.timeout: timer = Timer(options.timeout / 1000, event.set) timer.daemon = True timer.start() self._verify_rp_id(options.rp.id) client_data = self._build_client_data( WEBAUTHN_TYPE.MAKE_CREDENTIAL, options.challenge ) selection = options.authenticator_selection or AuthenticatorSelectionCriteria() try: att_resp, extension_outputs = self._do_make_credential( client_data, options.rp, options.user, options.pub_key_cred_params, options.exclude_credentials, options.extensions, selection.require_resident_key, selection.user_verification, pin, event, on_keepalive, ) return AuthenticatorAttestationResponse( client_data, AttestationObject.create( att_resp.fmt, att_resp.auth_data, att_resp.att_stmt ), extension_outputs, ) except CtapError as e: raise _ctap2client_err(e) finally: if options.timeout: timer.cancel() def _ctap2_make_credential( self, client_data, rp, user, key_params, exclude_list, extensions, rk, user_verification, pin, event, on_keepalive, ): if exclude_list: # Filter out credential IDs which are too long max_len = self.info.max_cred_id_length if max_len: exclude_list = [e for e in exclude_list if len(e) <= max_len] # Reject the request if too many credentials remain. max_creds = self.info.max_creds_in_list if max_creds and len(exclude_list) > max_creds: raise ClientError.ERR.BAD_REQUEST("exclude_list too long") # Process extensions client_inputs = extensions or {} extension_inputs = {} used_extensions = [] try: for ext in [cls(self.ctap2) for cls in self.extensions]: auth_input = ext.process_create_input(client_inputs) if auth_input is not None: used_extensions.append(ext) extension_inputs[ext.NAME] = auth_input except ValueError as e: raise ClientError.ERR.CONFIGURATION_UNSUPPORTED(e) # Handle auth pin_protocol, pin_auth, internal_uv = self._get_auth_params( client_data, rp["id"], user_verification, pin, event, on_keepalive ) if not (rk or internal_uv): options = None else: options = {} if rk: options["rk"] = True if internal_uv: options["uv"] = True att_obj = self.ctap2.make_credential( client_data.hash, rp, user, key_params, exclude_list or None, extension_inputs or None, options, pin_auth, pin_protocol, event, on_keepalive, ) # Process extenstion outputs extension_outputs = {} try: for ext in used_extensions: output = ext.process_create_output(att_obj.auth_data) if output is not None: extension_outputs.update(output) except ValueError as e: raise ClientError.ERR.CONFIGURATION_UNSUPPORTED(e) return att_obj, extension_outputs def _ctap1_make_credential( self, client_data, rp, user, key_params, exclude_list, extensions, rk, user_verification, pin, event, on_keepalive, ): if ( rk or user_verification == UserVerificationRequirement.REQUIRED or ES256.ALGORITHM not in [p.alg for p in key_params] ): raise CtapError(CtapError.ERR.UNSUPPORTED_OPTION) app_param = sha256(rp["id"].encode()) dummy_param = b"\0" * 32 for cred in exclude_list or []: key_handle = cred["id"] try: self.ctap1.authenticate(dummy_param, app_param, key_handle, True) raise ClientError.ERR.OTHER_ERROR() # Shouldn't happen except ApduError as e: if e.code == APDU.USE_NOT_SATISFIED: _call_polling( self.ctap1_poll_delay, event, on_keepalive, self.ctap1.register, dummy_param, dummy_param, ) raise ClientError.ERR.DEVICE_INELIGIBLE() return ( AttestationObject.from_ctap1( app_param, _call_polling( self.ctap1_poll_delay, event, on_keepalive, self.ctap1.register, client_data.hash, app_param, ), ), {}, ) def get_assertion( self, options: PublicKeyCredentialRequestOptions, pin: Optional[str] = None, event: Optional[Event] = None, on_keepalive: Optional[Callable[[int], None]] = None, ): """Get an assertion. :param options: PublicKeyCredentialRequestOptions data. :param pin: (optional) Used if PIN verification is required. :param threading.Event event: (optional) Signal to abort the operation. :param on_keepalive: (optional) Not implemented. """ options = PublicKeyCredentialRequestOptions._wrap(options) event = event or Event() if options.timeout: timer = Timer(options.timeout / 1000, event.set) timer.daemon = True timer.start() self._verify_rp_id(options.rp_id) client_data = self._build_client_data( WEBAUTHN_TYPE.GET_ASSERTION, options.challenge ) try: assertions, used_extensions = self._do_get_assertion( client_data, options.rp_id, options.allow_credentials, options.extensions, options.user_verification, pin, event, on_keepalive, ) return Fido2ClientAssertionSelection( client_data, assertions, used_extensions, ) except CtapError as e: raise _ctap2client_err(e) finally: if options.timeout: timer.cancel() def _ctap2_get_assertion( self, client_data, rp_id, allow_list, extensions, user_verification, pin, event, on_keepalive, ): pin_protocol, pin_auth, internal_uv = self._get_auth_params( client_data, rp_id, user_verification, pin, event, on_keepalive ) options = {"uv": True} if internal_uv else None if allow_list: # Filter out credential IDs which are too long max_len = self.info.max_cred_id_length if max_len: allow_list = [e for e in allow_list if len(e) <= max_len] if not allow_list: raise CtapError(CtapError.ERR.NO_CREDENTIALS) # Reject the request if too many credentials remain. max_creds = self.info.max_creds_in_list if max_creds and len(allow_list) > max_creds: raise ClientError.ERR.BAD_REQUEST("allow_list too long") # Process extensions client_inputs = extensions or {} extension_inputs = {} used_extensions = [] try: for ext in [cls(self.ctap2) for cls in self.extensions]: auth_input = ext.process_get_input(client_inputs) if auth_input is not None: used_extensions.append(ext) extension_inputs[ext.NAME] = auth_input except ValueError as e: raise ClientError.ERR.CONFIGURATION_UNSUPPORTED(e) assertions = self.ctap2.get_assertions( rp_id, client_data.hash, allow_list or None, extension_inputs or None, options, pin_auth, pin_protocol, event, on_keepalive, ) return assertions, used_extensions def _ctap1_get_assertion( self, client_data, rp_id, allow_list, extensions, user_verification, pin, event, on_keepalive, ): if user_verification == UserVerificationRequirement.REQUIRED or not allow_list: raise CtapError(CtapError.ERR.UNSUPPORTED_OPTION) app_param = sha256(rp_id.encode()) client_param = client_data.hash for cred in allow_list: try: auth_resp = _call_polling( self.ctap1_poll_delay, event, on_keepalive, self.ctap1.authenticate, client_param, app_param, cred["id"], ) assertions = [AssertionResponse.from_ctap1(app_param, cred, auth_resp)] return assertions, [] except ClientError as e: if e.code == ClientError.ERR.TIMEOUT: raise # Other errors are ignored so we move to the next. raise ClientError.ERR.DEVICE_INELIGIBLE() _WIN_INFO = Info.create(versions=["U2F_V2", "FIDO_2_0"], aaguid=b"\0" * 32) foo = _WIN_INFO.aaguid if platform.system().lower() == "windows": try: from .win_api import ( WinAPI, WebAuthNAuthenticatorAttachment, WebAuthNUserVerificationRequirement, WebAuthNAttestationConvoyancePreference, ) except Exception: # nosec # TODO: Make this less generic pass class WindowsClient(_BaseClient): """Fido2Client-like class using the Windows WebAuthn API. Note: This class only works on Windows 10 19H1 or later. This is also when Windows started restricting access to FIDO devices, causing the standard client classes to require admin priveleges to run (unlike this one). The make_credential and get_assertion methods are intended to work as a drop-in replacement for the Fido2Client methods of the same name. :param str origin: The origin to use. :param verify: Function to verify an RP ID for a given origin. :param ctypes.wintypes.HWND handle: (optional) Window reference to use. """ def __init__( self, origin: str, verify: Callable[[str, str], bool] = verify_rp_id, handle=None, ): super(WindowsClient, self).__init__(origin, verify) self.api = WinAPI(handle) @property def info(self) -> Info: return _WIN_INFO @staticmethod def is_available() -> bool: return platform.system().lower() == "windows" and WinAPI.version > 0 def make_credential(self, options, **kwargs): """Create a credential using Windows WebAuthN APIs. :param options: PublicKeyCredentialCreationOptions data. :param threading.Event event: (optional) Signal to abort the operation. """ options = PublicKeyCredentialCreationOptions._wrap(options) self._verify_rp_id(options.rp.id) client_data = self._build_client_data( WEBAUTHN_TYPE.MAKE_CREDENTIAL, options.challenge ) selection = options.authenticator_selection or AuthenticatorSelectionCriteria() try: result = self.api.make_credential( options.rp, options.user, options.pub_key_cred_params, client_data, options.timeout or 0, selection.require_resident_key or False, WebAuthNAuthenticatorAttachment.from_string( selection.authenticator_attachment or "any" ), WebAuthNUserVerificationRequirement.from_string( selection.user_verification or "discouraged" ), WebAuthNAttestationConvoyancePreference.from_string( options.attestation or "none" ), options.exclude_credentials, options.extensions, kwargs.get("event"), ) except OSError as e: raise ClientError.ERR.OTHER_ERROR(e) return AuthenticatorAttestationResponse( client_data, AttestationObject(result), {} ) def get_assertion(self, options, **kwargs): """Get assertion using Windows WebAuthN APIs. :param options: PublicKeyCredentialRequestOptions data. :param threading.Event event: (optional) Signal to abort the operation. """ options = PublicKeyCredentialRequestOptions._wrap(options) self._verify_rp_id(options.rp_id) client_data = self._build_client_data( WEBAUTHN_TYPE.GET_ASSERTION, options.challenge ) try: (credential, auth_data, signature, user_id) = self.api.get_assertion( options.rp_id, client_data, options.timeout or 0, WebAuthNAuthenticatorAttachment.ANY, WebAuthNUserVerificationRequirement.from_string( options.user_verification or "discouraged" ), options.allow_credentials, options.extensions, kwargs.get("event"), ) except OSError as e: raise ClientError.ERR.OTHER_ERROR(e) user = {"id": user_id} if user_id else None return AssertionSelection( client_data, [ AssertionResponse.create( credential=credential, auth_data=auth_data, signature=signature, user=user, ) ], )