can an arduino be encrypted?

Is it possible to prevent a board from being read so your work can not be copied

Is it really necessary? Fuse bits can be set to prevent reading the hex file on the Arduino. But, even if someone gets the hex file off the Arduino, all that they can do with it is load it on another Arduino.

Hold down the Shift key while uploading a sketch. You'll see a lot more output, including the location of the hex file that gets uploaded. Look at that file, and see if any addition action on your part is really necessary.