New to Java

Hi Friends,
I am trying to read some characters from a file but it's adding some unknown characters to it. The source file has this line:

0??0

I use this code to read the characters from the source file:

            File inputfile = new File("myfile.txt");
	    FileInputStream from = new FileInputStream(inputfile);
	    byte [] buffer = new byte[4096];
	    int charsread;
	    while((charsread = from.read(buffer)) != -1);
	    from.close();
	    String text = new String(buffer);
	    text = text.trim();
	    String publickey = text.toLowerCase();

But the output has an extra '?' symbol in it i.e.

0?0

Basicallty, the file i am trying to read is a rsa public key and I am not sure if it has to do something with encoding. Can someone please help?

Thanks