private void confirm_password() {
        Button confirm_button = (Button) findViewById(R.id.login_button);
        confirm_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final EditText entered_password = (EditText) findViewById(R.id.pass_checker);
                given_password = entered_password.getText().toString();

                Log.d("Podane haslo", given_password);


                String decode_pass_from_user = null;
                String decoded_pass_from_db = null;

                //zashashować hasło podane przez użytkownika
                MessageDigest messageDigest = null;
                try {
                    messageDigest = MessageDigest.getInstance("SHA-256");
                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }
                assert messageDigest != null;

                try {
                    messageDigest.update(given_password.getBytes("UTF-8"));
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
                String hashed_pass_from_user = Base64.encodeToString(messageDigest.digest(), Base64.URL_SAFE);

                hashed_pass_from_user = hashed_pass_from_user.substring(0,hashed_pass_from_user.length()-1);

                Log.d("z podanego do #2", hashed_pass_from_user);

                //zakodować i zdekodowac haslo od uzytkownika do porownania z baza
                //String hashed_pass_from_user = bytesToHex(messageDigest.digest());
               /* String hashed_pass_from_user = Base64.encodeToString(messageDigest.digest(), Base64.DEFAULT);
                byte[] data = Base64.decode(hashed_pass_from_user, Base64.DEFAULT);
                try {
                    decode_pass_from_user = new String(data, "UTF-8");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }*/

                // wydobyc haslo z bazy i zdekodowac
                String pass_from_db = null;
                try {
                    pass_from_db = getHashFromDatabase();
                  //  byte[] data2 = Base64.decode(pass_from_db, Base64.DEFAULT);
                  //  decoded_pass_from_db = new String(data2, "UTF-8");
                    Log.d("haslo zaciagniete z db", pass_from_db);

                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }

                // porównać zahashowane zdekodowane hasło od użytownika ze zdekodowanym hasłem z bazy
                assert pass_from_db != null;
                if (hashed_pass_from_user.matches(pass_from_db)) {
                    showLoggedInActivity();

                    //aktualizuje haslo z bazy do kolejnego hasha
                    //hashowanie
                    MessageDigest md = null;
                    try {
                        md = MessageDigest.getInstance("SHA-256");
                    } catch (NoSuchAlgorithmException e) {
                        e.printStackTrace();
                    }
                    assert md != null;

                    try {
                        md.update(pass_from_db.getBytes("UTF-8"));
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }

                    String new_hashed_pass_to_save = Base64.encodeToString(md.digest(), Base64.DEFAULT);

                    //zapis do bazy
                    saveHashToDatabase(new_hashed_pass_to_save);
                }
                else {
                    context = getApplicationContext();
                    CharSequence text = "Haslo jest nieprawidlowe!";
                    int duration = Toast.LENGTH_SHORT;
                    Toast toast = Toast.makeText(context, text, duration);
                    toast.show();

                    showEnterPasswordActivity();
                    }
                }
            });
    }