If that is swaged or somehow retained where the ring must be destroyed to remove the handle you can still secure it a couple other ways.Either make a collar to fit over the square shaft with a set screw or drill the square stock for a roll pin and use a washer to retain the escutcheon.Maybe add a wave washer/nylon washer to reduce rattling while there. It looks like the first 1/2" is what engages to the door latch so I'm assuming you have room for either.~RT