Simplest way to encrypt a text file in java

Question

For my School project I had to show that I can utilize file handling within a program. For this I made a very simple login process that you can create an account on that writes a username and password to a text file located in the resource folder. Obviously this has no security at all as it wasn't designed to be secure just to showcase file handling however my teacher has said that I should attempt to add some encryption to the file as well to get a better grade.

I have done some research and many people are recommending DES.

The problem I'm having is I don't have much time left for my project and need to finish it asap. Using DES seems like it would take a while to implement all the extra code.

In my program I am using a simple lineNumberReader to read the files line by line. To write to the files I am using a BufferedWriter.

Is there anyway to encrypt this data very simply? It doesn't have to be very secure but I need to show that I have atleast attempted to encrypt the data. The encryption and decryption would all be completed on the same application as data isn't being transferred.

Potentially a way I can create a very simple encryption and decryption algorithm myself?

Answer 1

An easy and fun scrambling algorithm would be the Burrows-Wheeler transform. Not really a secure encryption, but seriously, it's a school work and this is awesome.

Answer 2

Try this,... Its pretty simple

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

public class HelloWorld{
    public static void main(String[] args) {

        try{
            KeyGenerator keygenerator = KeyGenerator.getInstance("DES");
            SecretKey myDesKey = keygenerator.generateKey();

            Cipher desCipher;
            desCipher = Cipher.getInstance("DES");


            byte[] text = "No body can see me.".getBytes("UTF8");


            desCipher.init(Cipher.ENCRYPT_MODE, myDesKey);
            byte[] textEncrypted = desCipher.doFinal(text);

            String s = new String(textEncrypted);
            System.out.println(s);

            desCipher.init(Cipher.DECRYPT_MODE, myDesKey);
            byte[] textDecrypted = desCipher.doFinal(textEncrypted);

            s = new String(textDecrypted);
            System.out.println(s);
        }catch(Exception e)
        {
            System.out.println("Exception");
        }
    }
}

So basically before writing to file you will encrypt and after reading you will need to decrypt it.

Answer 3

use simple subtitute encryption algorythm, change every character into number or other character.

1. get every character of your string.
2. get the ascii value of the string.
3. add the ascii value with specific integer (this will be your encryption key)
4. display the result

Answer 4

A very basic method would be to xor the data with a key. This method is symmetrical, i.e you can use the same key to decode as encode.

If we choose a 1 byte key it's nice and simple, enough to make it unreadable (but not at all secure!):

private void encodeDecode(byte[] bytes, byte key) {
    for(int i=0; i<bytes.length; i++)
        bytes[i] = (byte) (bytes[i]^key);
}