AES Key From File Trouble

Question

Program is running now. It runs but then crashes. In my files folder it creates an encrypted file but it is blank. It also does not produce a decrypted file at all. I also changed the bit size to 128. What else I am missing in order to properly implement AES?

This is the modified program

import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.Cipher;

import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;
import java.security.InvalidAlgorithmParameterException;

import javax.crypto.NoSuchPaddingException;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;





import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.DESKeySpec;

public class MyCiphers {

    public static void main(String[] args) {
        try {



            BufferedReader br = new BufferedReader(new FileReader("key.txt"));
            String key = br.readLine();
            br.close();
            FileInputStream fis = new FileInputStream("original.txt");
            FileOutputStream fos = new FileOutputStream("encrypted.txt");
            encrypt(key, fis, fos);

            FileInputStream fis2 = new FileInputStream("encrypted.txt");
            FileOutputStream fos2 = new FileOutputStream("decrypted.txt");
            decrypt(key, fis2, fos2);

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

    public static void encrypt(String key, InputStream is, OutputStream os) throws Throwable {
        encryptOrDecrypt(key, Cipher.ENCRYPT_MODE, is, os);
    }

    public static void decrypt(String key, InputStream is, OutputStream os) throws Throwable {
        encryptOrDecrypt(key, Cipher.DECRYPT_MODE, is, os);
    }

    public static void encryptOrDecrypt(String key, int mode, InputStream is, OutputStream os) throws Throwable {


      SecretKeySpec dks = new SecretKeySpec(key.getBytes(),"AES");
        Cipher cipher = Cipher.getInstance("AES"); 

        if (mode == Cipher.ENCRYPT_MODE) {
            cipher.init(Cipher.ENCRYPT_MODE, dks);
            CipherInputStream cis = new CipherInputStream(is, cipher);
            doCopy(cis, os);        
        } else if (mode == Cipher.DECRYPT_MODE) {
            cipher.init(Cipher.DECRYPT_MODE, dks);
            CipherOutputStream cos = new CipherOutputStream(os, cipher);
            doCopy(is, cos);
        }


    }

    public static void doCopy(InputStream is, OutputStream os) throws IOException {
        byte[] bytes = new byte[128];
        int numBytes;
        while ((numBytes = is.read(bytes)) != -1) {
            os.write(bytes, 0, numBytes);
        }
        os.flush();
        os.close();
        is.close();
    }

}

James Barnett · Answer 1 · 2014-03-26T00:38:41.653

0

As the error message says, there is no method getBytes() for the type InputStream. You need to read the key and store it as a String.

eg. rather than FileInputStream fisk ... do

BufferedReader br = new BufferedReader(new FileReader("Key.txt"));
String key = br.readLine();
br.close();

(assuming that your key file just contains the key on one line)

Then change your encrypt/decrypt and encryptOrDecrypt methods to take in the key as a String rather than InputStream eg. encrypt(String key, InputStream is, OutputStream os)

Then you can call SecretKeySpec(key.getBytes(),"DES");

Also you realise that this is DES, not AES as you say right? If you want to use AES you will need a 128 bit key (or 192/256 bits)

edited Mar 26 '14 at 00:38

answered Mar 26 '14 at 00:33

James Barnett

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Thank you for your help! Program is crashing now when I run it but I get no error message. Please see my new code above! Thank you – user3294617 Mar 26 '14 at 03:52
You also posted this in another question and said it works? So did this solve your problem? please tick it as accepted if so – James Barnett Mar 26 '14 at 12:07

AES Key From File Trouble

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