HD-DVD key has been cracked. Get the hex he

You'll probably need some epoxy and some good clamps to fix that
crack. Or maybe JB-weld. But if it regularly stands up to a lot of
torque, you'll probably want to get a new one. DAGS.
And I don't need any new hexes - if I needed a hexagon, I'd probably
set my bandsaw table or miter guage to 30* and cut the piece upside
down to get the 60* angle, since I don't have a miter saw or table
saw. A shooting board with my low-angle block plane would make it
nice and smooth.
Sorry to hear about your key,
Andy