Android Encryption and Encryption

Question

I’m trying to learn how to use encryption to encrypt and decrypt messages.

I’m with a class called Encripta which has the methods, the encryption works perfectly.

My method of deciphering cryptography decrypt, returns the following log:

"V/Decrypted: android.support.v7.widget.Appcompatedittext{41766b38 VFED.. CL .F...... 32,344-688,435 #7f0c0052 app:id/txtMensage}"

I’ll post my class Main and the class Encripta.

If you can tell me what I’m missing, I’m waiting( I took the code here from the same stack, and I’m using the base in the project).

Encryption

package gastecnologia.com.br.ltcrypt;

import android.util.Base64;

import java.security.MessageDigest;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by thiago.goncalves on 22/02/2016.
 */
public class Encripta {

    private final Cipher cipher;
    private final SecretKeySpec key;
    private AlgorithmParameterSpec spec;
    public static final String SEED_16_CHARACTER = "U1MjU1M0FDOUZ.Qz";

    public Encripta() throws Exception {
        // hash password with SHA-256 and crop the output to 128-bit for key
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        digest.update(SEED_16_CHARACTER.getBytes("UTF-8"));
        byte[] keyBytes = new byte[32];
        System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length);

        cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
        key = new SecretKeySpec(keyBytes, "AES");
        spec = getIV();
    }

    public AlgorithmParameterSpec getIV() {
        byte[] iv = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };
        IvParameterSpec ivParameterSpec;
        ivParameterSpec = new IvParameterSpec(iv);

        return ivParameterSpec;
    }

    public String encrypt(String plainText) throws Exception {
        cipher.init(Cipher.ENCRYPT_MODE, key, spec);
        byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));
        String encryptedText = new String(Base64.encode(encrypted,
                Base64.DEFAULT), "UTF-8");

        return encryptedText;
    }

    public String decrypt(String cryptedText) throws Exception {
        cipher.init(Cipher.DECRYPT_MODE, key, spec);
        byte[] bytes = Base64.decode(cryptedText, Base64.DEFAULT);
        byte[] decrypted = cipher.doFinal(bytes);
        String decryptedText = new String(decrypted, "UTF-8");

        return decryptedText;
    }

}

package gastecnologia.com.br.ltcrypt;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

    String mensagemCriptografada;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

            Button btnCodificar     = (Button) findViewById(R.id.btnCodificar);
            Button btnDecrifrar     = (Button) findViewById(R.id.btnDecifrar);
            Button btnLimpar        = (Button) findViewById(R.id.btnLimpar);
            Button btnCopiar        = (Button) findViewById(R.id.btnCopiar);
            final EditText txtMensagem    = (EditText) findViewById(R.id.txtMensagem);

            btnCodificar.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {

                        Log.v("Btn codificar", "ok");
                        try {

                            Encripta encripta = new Encripta();
                            String codigo =  encripta.encrypt(txtMensagem.toString());
                            Log.v("Criptografia",codigo);
                            txtMensagem.setText(codigo);
                            mensagemCriptografada = codigo;


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

                    }
            });


            btnDecrifrar.setOnClickListener(new View.OnClickListener() {
                @Override
                    public void onClick(View v) {
                        Log.v("Btn Decifrar","ok");

                        try {

                            Encripta encripta = new Encripta();
                           // encripta.getIV();
                            String codigoDecifrado =  encripta.decrypt(mensagemCriptografada.toString());

                            Log.v("Mmg a ser Decifrada",codigoDecifrado);

                            Log.v("Decifrado",codigoDecifrado);



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

                    }
            });

           btnLimpar.setOnClickListener(new View.OnClickListener() {
               @Override
               public void onClick(View v) {
                   txtMensagem.setText("");
               }
           });



    }




}

Answer 1

Come on:

I believe there are no errors in the Encrypt methods, but there is when you take the value of the screen:

String codigo =  encripta.encrypt(txtMensagem.toString());

Actually you are passing the object reference, not its content:

The right thing would be :

 String codigo =  encripta.encrypt(txtMensagem.getText().toString());