Question

How can I convert this byte[] to String :

byte[] mytest = new byte[] {100,25,28,-122,-26,94,-3,-26};

i get this : "d��^�" when I use :

new String( mytest , "UTF-8" )

Here is code java for creation of key :

m_key = new javax.crypto.spec.SecretKeySpec(new byte[] {100,25,28,-122,-26,94,-3,-26}, "DES");

Thanks.

Answer 1

In order to decode the byte array into something like ASCII, you need to know its original encoding. Otherwise you would need to treat it as binary.

Note: Base64 is intended for transferring binary data across networks.

I would suggest Base64 encoding your byte array. Then in your PHP code decoding the Base64 string back into a UTF-8 string.

In Java, here’s how to Base64 encode your byte array and then decode it back to UTF-8:

import org.apache.commons.codec.binary.Base64;

public class MyTest {
    public static void main(String[] args) throws Exception {
        byte[] byteArray = new byte[] {100,25,28,-122,-26,94,-3,-26};
        System.out.println("To UTF-8 string: " + new String(byteArray, "UTF-8"));

        byte[] base64 = Base64.encodeBase64(byteArray);
        System.out.println("To Base64 string: " + new String(base64, "UTF-8"));

        byte[] decoded = Base64.decodeBase64(base64);
        System.out.println("Back to UTF-8 string: " + new String(decoded, "UTF-8"));

        /* the decoded byte array is the same as the original byte array */
        for (int i = 0; i < decoded.length; i++) {
            assert byteArray[i] == decoded[i];
        }
    }
}

The output from the above code is:

To UTF-8 string: d��^�
To Base64 string: ZBkchuZe/eY=
Back to UTF-8 string: d��^�

So if you wanted to use the same binary data in your PHP code, cut and paste the Base64 string into your PHP code and decode it back to UTF-8. Something like this:

<?php
$str = 'ZBkchuZe/eY=';
$key = base64_decode($str);
echo $key;
?>

I don’t code in PHP, but you should be able to decode Base64 using this method:
http://php.net/manual/en/function.base64-decode.php

The above code should echo back the original binary data as UTF-8 (albeit with funny characters). The point is that the funny-looking string in the $key variable is representing the same binary data you had in the Java byte array:

d��^�

You should be able to pass the $key variable into your PHP encryption method.