Press space to start. Type the shift amount (1-25) Type your phrase (letters and spaces only) A shift of 26 gives you the same phrase, and putting a number more than that just loops around.
This is a ROT-n encoder. (also known as a Caesar Shift) It takes text and shifts it so that it is not easy to read. You can find more info at: http://www.rot-n.com/ A shift of 26 gives you the same phrase, and putting a number more than that just loops around.