Goldfinger.Builder(context).build()

if (goldfinger.canAuthenticate(@AuthenticatorTypes int authenticators)) {
  /* Authenticate */
}

Goldfinger.PromptParams params = new Goldfinger.PromptParams.Builder(activity)
  .title("Title")
  .negativeButtonText("Cancel")
  .description("Description")
  .subtitle("Subtitle")
  .build();

goldfinger.authenticate(params, new Goldfinger.Callback() {
    @Override
    public void onError(@NonNull Exception e) {
        /* Critical error happened */
    }

    @Override
    public void onResult(@NonNull Goldfinger.Result result) {
        /* Result received */
    }
});

RxGoldfinger.Builder(context).build()

goldfinger.authenticate(params).subscribe(new DisposableObserver<Goldfinger.Result>() {

  @Override
  public void onComplete() {
    /* Fingerprint authentication is finished */
  }

  @Override
  public void onError(Throwable e) {
    /* Critical error happened */
  }

  @Override
  public void onNext(Goldfinger.Result result) {
    /* Result received */
  }
});

Goldfinger.Builder(context)
  .logEnabled(true)
  .cipherFactory(factory)
  .cipherCrypter(crypter)
  .build()

new CipherFactory() {
  @Nullable
  @Override
  public Cipher createEncryptionCrypter(String key) {
     /* Create Cipher for encryption */
  }

  @Nullable
  @Override
  public Cipher createDecryptionCrypter(String key) {
    /* Create Cipher for decryption */
  }
};

new CipherCrypter() {
  @Nullable
  @Override
  public String encrypt(@NonNull Cipher crypter, @NonNull String value) {
    /* Encrypt data with given crypter */
  }

  @Nullable
  @Override
  public String decrypt(@NonNull Cipher crypter, @NonNull String value) {
    /* Decrypt data with given crypter */
  }
};