It's pretty difficult to make a stealth platform out of something that is constantly transmitting regardless of how secure and reliable that connection is. If your solution is to make the drone-based system autonomous (no communications required), then you might as well skip the whole drone bomber platform altogether and just use ballistic missiles.
Wrong, for a couple of reasons. First off, reusable autonomous bombers would be much less expensive than missiles per ton of delivered ordinance. Second, you can communicate with autonomous aircraft without compromising their stealth. Even if they send data back, it can be quite stealthy (directional satcom), but this would likely not be needed continuously, or even often. Damage assessment could be done with video stored on the vehicle until landing, for instance.
Personally I would be cautious about allowing remote retargeting, since if your encryption scheme was compromised your own weapons could be turned against you. You could still enable a 'recall' command. If you did allow retargeting, that would seem to be the perfect spot for one time pad encryption.
The US Navy is already developing an autonomous bomber, based on the X-47 program.