Convert byte[] to String Java Android Encryption

Question

I am using the JNCryptor library to encrypt a string before sending it to my server as an encrypted string. Here is my code:

    String teststring = "Hello World";
    JNCryptor cryptor = new AES256JNCryptor();
    byte[] plaintext = teststring.getBytes();
    String password = "test";

    try {
        byte[] ciphertext = cryptor.encryptData(plaintext, password.toCharArray());

        String a = new String(ciphertext);
        return a;


    } catch (CryptorException e) {
        // Something went wrong
        e.printStackTrace();

        return "0";
    }

However, when I send my string "a" to the server, it has a bunch of unrecognizable characters. I read an explanation regarding this:

String is not a suitable container for binary data and ciphertext is binary data. For any given character encoding not all bytes and byte sequences represents characters and when an un-representable byte or sequence is found it is converted to some error character. Obviously this error character cannot be converted back to a unique byte or byte sequence (it is a many->one mapping).

Is this advice correct? In that case, how do I convert the byte[] to a string correctly? So that I can readably store it on my server?

Answer 1

There is no standard way for converting from a byte array to a string. You have to encode the byte array. A common way to do this is base64 encoding. For an explanation of how base64 encoding works: http://en.wikipedia.org/wiki/Base64

Then once it gets to your server, base64 decode it back into your original byte array and store it, done!