How do I encrypt/decrypt a string with another string as a password?

Question

I\'m making a simple program that takes text entered in a text box, and takes a password that\'s in another text box, then does some sort of simple encryption on it and saves it

Answer 1

You're trying to re-invent the wheel. Unless you're doing it for fun, I'd recommend using something like AES. If you just google "AES in java" you'll find a number of examples.

If you are doing it for fun and want something simple to implement, have a look at ROT13 as well.

Here's an example for AES in Java:

private static final String ALGORITHM = "AES";
private static final byte[] keyValue = 
    new byte[] { 'T', 'h', 'i', 's', 'I', 's', 'A', 'S', 'e', 'c', 'r', 'e', 't', 'K', 'e', 'y' };

 public String encrypt(String valueToEnc) throws Exception {
    Key key = generateKey();
    Cipher c = Cipher.getInstance(ALGORITHM);
    c.init(Cipher.ENCRYPT_MODE, key);
    byte[] encValue = c.doFinal(valueToEnc.getBytes());
    String encryptedValue = new BASE64Encoder().encode(encValue);
    return encryptedValue;
}

public String decrypt(String encryptedValue) throws Exception {
    Key key = generateKey();
    Cipher c = Cipher.getInstance(ALGORITHM);
    c.init(Cipher.DECRYPT_MODE, key);
    byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedValue);
    byte[] decValue = c.doFinal(decordedValue);
    String decryptedValue = new String(decValue);
    return decryptedValue;
}

private static Key generateKey() throws Exception {
    Key key = new SecretKeySpec(keyValue, ALGORITHM);
    return key;
}

You may want to improve on this code.