exampleutils.py

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"""
Utilities for common functionality used by several examples in this directory.
"""

from fido2.hid import CtapHidDevice
from fido2.client import Fido2Client, WindowsClient, UserInteraction
from getpass import getpass
import ctypes


try:
    from fido2.pcsc import CtapPcscDevice
except ImportError:
    CtapPcscDevice = None


# Handle user interaction via CLI prompts
class CliInteraction(UserInteraction):
    def __init__(self):
        self._pin = None

    def prompt_up(self):
        print("\nTouch your authenticator device now...\n")

    def request_pin(self, permissions, rd_id):
        if not self._pin:
            self._pin = getpass("Enter PIN: ")
        return self._pin

    def request_uv(self, permissions, rd_id):
        print("User Verification required.")
        return True


def enumerate_devices():
    for dev in CtapHidDevice.list_devices():
        yield dev
    if CtapPcscDevice:
        for dev in CtapPcscDevice.list_devices():
            yield dev


def get_client(predicate=None, **kwargs):
    """Locate a CTAP device suitable for use.

    If running on Windows as non-admin, the predicate check will be skipped and
    a webauthn.dll based client will be returned.

    Extra kwargs will be passed to the constructor of Fido2Client.
    """
    if WindowsClient.is_available() and not ctypes.windll.shell32.IsUserAnAdmin():
        # Use the Windows WebAuthn API if available, and we're not running as admin
        return WindowsClient("https://example.com")

    user_interaction = kwargs.pop("user_interaction", None) or CliInteraction()

    # Locate a device
    for dev in enumerate_devices():
        # Set up a FIDO 2 client using the origin https://example.com
        client = Fido2Client(
            dev,
            origin=kwargs.pop('origin', None) or "https://example.com",
            user_interaction=user_interaction,
            **kwargs,
        )
        # Check if it is suitable for use
        if predicate is None or predicate(client):
            return client
    else:
        raise ValueError("No suitable Authenticator found!")