I like to make my keys out of play doe, this way when it hardens I can go sit in the lobby of my bank half dressed with this big bandage on my head and lick my keys. They have these Top Secret flavour crystals in them that just explode in your mouth.
Just saying, it comes in handy when the bank cuts you off from the mints.
Normally, the Key isn't used for the Door. They Key is used for the LOCK that is installed in the Door. Getting terminology right is crucial, straight away, in order to fairly answer your queries.
If you want to make your door Secure, I would recommend building a solid wall immediately behind it. That way, even if the door does fail & open, access to the demise behind would not be possible. Think of it as a Redundant Security System
The terminology is very important, but I do think that working to actively make your lock secure also makes your front door secure. It seems like the OP merely missed a step in explaining her question.
Personally, I advocate for the use of secure deadbolts on exterior doors, simply because they put up much more resistance than some other locks I've had experience with. I currently have a Grade 1 double sided deadbolt installed on my front door and it works just fine for me right now. I am not sure if that particular lock will work well with your double doors. However, there are some deadbolt locks that are fashioned to work with double doors so I suggest you take a look at those.
In addition to whatever door lock you choose, there are additional tricks you can take advantage of to make your front door security better. Based on your question, it seems to me like security is your main concern, so I'll see if I can help you with that. Try and remember that security is all about layers, kind of like the layers of icing on a cake. As such, just having a good door lock installed on your double doors will not get you very far if there are no other security layers built around it. I really think this article might help give you some nifty ideas about keeping your door secure: https://unitedlocksmith.net/blog/12-best-ways-to-secure-a-door
Personally, I utilize security cameras and security screens as extra precautions around my door, as well of some of the other things mentioned on that list. The reason for this is simple. I want to make it harder for anyone to get access to my front door, and if they do I want to see who's there and what they're doing. Documenting events is important. I think the first and second points made in that article will help you with your double doors. Focusing more on the construction of the door helps a lot, meaning you should ideally have solid core double doors. Then when it comes to your locks and hinges, using longer screws will really help fasten parts of the door and lock into the frame. This simple gesture makes it much harder for your door to be compromised. I hope this helps answer your question to some extent.