Strong customer authentication with FIDO2

func userClient(_ userClient: UserClient,
                didReceiveCustomAuthFinishAuthenticationChallenge challenge: CustomAuthFinishAuthenticationChallenge) {

    // responsePayload from extension engine init script: { fido2: {...}, userId: "..." }
    guard let responseJson = challenge.info?.data,
          let responseData = responseJson.data(using: .utf8),
          let payload = try? JSONSerialization.jsonObject(with: responseData) as? [String: Any],
          let fido2Options = payload["fido2"],
          let userId = payload["userId"] as? String else {
        challenge.sender.cancel(challenge, underlyingError: nil)
        return
    }

    do {
        // Extract the WebAuthn CredentialRequestOptions and pass to FIDO SDK
        let fido2OptionsData = try JSONSerialization.data(withJSONObject: fido2Options)
        let fido2OptionsString = String(data: fido2OptionsData, encoding: .utf8)!

        let fidoRequest = try TGFFido2RequestFactory.request(withJsonString: fido2OptionsString)
        let respondArgsBuilder = TGFFido2RespondArgsBuilder(request: fidoRequest, uiDelegate: fidoUiDelegate)
        respondArgsBuilder.uiBiometricAuthenticatorDelegate = fidoUiDelegate
        respondArgsBuilder.uiPasscodeAuthenticatorDelegate = fidoUiDelegate
        respondArgsBuilder.passcodeAuthenticator = TGFPasscodeAuthenticator(delegate: fidoUiDelegate)
        let respondArgs = respondArgsBuilder.respondArgs()

        fido2Client.respond(with: respondArgs) { response, error in
            if let error = error {
                challenge.sender.cancel(challenge, underlyingError: error)
            } else if let fidoResponseJson = response?.raw() {
                // Wrap FIDO2 assertion with userId for the Complete script
                let completePayload: [String: Any] = [
                    "userId": userId,
                    "fido2": fidoResponseJson
                ]
                if let data = try? JSONSerialization.data(withJSONObject: completePayload),
                   let payloadString = String(data: data, encoding: .utf8) {
                    challenge.sender.respond(with: payloadString, to: challenge)
                }
            }
        }
    } catch {
        challenge.sender.cancel(challenge, underlyingError: error)
    }
}

public class FidoScaAuthenticationAction implements OneginiCustomAuthAuthenticationAction {

    private final Activity activity;
    private final Fido2UiCallback uiCallback;

    // Constructor initializing activity and UI callbacks...

    @Override
    public void finishAuthentication(final OneginiCustomAuthAuthenticationCallback callback,
                                     final String data) {
        try {
            // responsePayload from Extension Engine Init: { fido2: {...}, userId: "..." }
            JSONObject payload = new JSONObject(data);
            final String userId = payload.getString("userId");
            JSONObject fido2Options = payload.getJSONObject("fido2");

            // Extract WebAuthn CredentialRequestOptions and pass to FIDO SDK
            Fido2Request fido2Request = Fido2Request.jsonText(fido2Options.toString());

            PasscodeAuthenticatorCallback passcodeCallback = new SamplePinPadAuthenticatorCallback(activity);
            PasscodeAuthenticator passcodeAuthenticator = PasscodeAuthenticator.of(activity, passcodeCallback);
            BiometricAuthenticatorCallback biometricCallback = new SampleBiometricAuthenticatorCallback();

            Fido2RespondArgs args = new Fido2RespondArgs.Builder()
                .setFido2Request(fido2Request)
                .setUiCallback(uiCallback)
                .setPasscodeAuthenticatorCallback(passcodeCallback)
                .setPasscodeAuthenticator(passcodeAuthenticator)
                .setBiometricAuthenticatorCallback(biometricCallback)
                .build();

            Fido2Client client = Fido2ClientFactory.createFido2Client(activity);
            client.setActivity(activity);

            client.respondWithArgs(args, new Fido2ResponseCallback() {
                @Override
                public void onResponded(Fido2Response response) {
                    // Wrap FIDO2 assertion with userId for the Complete script
                    try {
                        JSONObject completePayload = new JSONObject();
                        completePayload.put("userId", userId);
                        completePayload.put("fido2", response.toJson());
                        callback.returnSuccess(completePayload.toString());
                    } catch (JSONException e) {
                        callback.returnError(e);
                    }
                }

                @Override
                public void onError(Fido2Exception exception) {
                    callback.returnError(exception);
                }
            });
        } catch (JSONException e) {
            callback.returnError(e);
        }
    }
}