public class MainActivity extends AppCompatActivity implements SecurityKeyDialogCallback<PivSecurityKey> {

    private void showSecurityKeyDialog() {
        SecurityKeyDialogOptions options = SecurityKeyDialogOptions.builder()
                //.setPinLength(4) // smartcards with a fixed PIN and PUK length improve the UX
                //.setPukLength(8)
                .build();

        SecurityKeyDialogFragment<PivSecurityKey> securityKeyDialogFragment =
                PivSecurityKeyDialogFragment.newInstance(options);
        securityKeyDialogFragment.show(getSupportFragmentManager());
    }

    @Override
    public void onSecurityKeyDialogDiscovered(SecurityKeyDialogInterface dialogInterface,
                                              PivSecurityKey securityKey, PinProvider pinProvider) throws IOException {
        SecurityKeyTlsClientCertificateAuthenticator clientCertificateAuthenticator =
                securityKey.createSecurityKeyClientCertificateAuthenticator(pinProvider);
        SSLContext sslContext = clientCertificateAuthenticator.buildInitializedSslContext();

        // connection with OkHttp
        OkHttpClient httpClient = new OkHttpClient.Builder()
                .sslSocketFactory(sslContext.getSocketFactory())
                .build();
        Request request = new Request.Builder()
                .url("https://tls.hwsecurity.dev")
                .build();
        Response response = httpClient.newCall(request).execute();
    }
}