If you're gonna do this, why not opt for LEDs? Better still, a laser, to make the beam difficult to see off-angle, e.g. from a nearby periscope?
And if your adversary hacks into your tablet, what messages will really be sent?
I have this nasty scenario in mind, like BSG's miniseries - western ships entering combat against Chinese or Russians, and Windows for Warships goes BSOD ...