Java string to bytearray back to string

Question

I have a client and server java application that needs have encrypted text passing through each other. I am using an XOR encryption the encrypt the text that I want.

The problem is that readline() doesn't accept string that has been XORed and will only if accepted if it is in bytes.

So I've converted my plaintext (string) into a byte array on the client side, and tried to convert back to a string on the server side.

Sadly, the result I am looking for is still jibberish and not the plaintext that I seeked.

Does anyone know how to make bytearrays change back to the original string? Or is there a better way to send through an XOR encrypted text through the readline() function?

Answer 1

After you've applied something like XOR, you end up with arbitrary binary data - not an encoded string.

The conventional safe way to convert arbitrary binary into text is to use base64 - don't try to just create a new string from it. So your process would be something like this:

• Start with plain text as a string.
• Encode the plain text using UTF-8, UTF-16 or something similar. Don't use the platform default encoding, or anything restrictive like ASCII. You now have a byte array.
• Apply your encryption. (XOR is pretty weak, but let's leave that to one side.) You still have a byte array.
• Apply base64 encoding to get a string.

Then when you need to decrypt...

• Apply base64 decoding to convert your string into a byte array.
• Apply your binary decryption process (e.g. XOR again). You still have a byte array.
• Now decode that byte array into a string, e.g. with new String(data, utf8Charset) to get back the original string.

There are various Java base64 libraries available, such as this class in Apache Commons Codec. (You'd want the encodeToString(byte[]) and decode(String) methods.)

Answer 2

answer from http://www.mkyong.com/java/how-do-convert-byte-array-to-string-in-java/

            String example = "This is an example";
               //Convert String to byte[] using .getBytes() function
            byte[] bytes = example.getBytes();
               //Convert byte[] to String using new String(byte[])      
            String s = new String(bytes);