The entire concept of a backdoor that only the good guys have the keys too is so moroinic as to make my blood boil. The TSA locks were picked because a photo of the keys were posted online. The NSA forced an encryption method that they knew how to defeat got pwned. Yet the backdoor method still gets bandied about like it's the one thing to save us when it is exactly what will sink us.
The attackers didn't get the keys to the back door. They actually replaced the entire door with a new door that they made, which went unnoticed (by Juniper) for 3 years, locking out the owners of the original back door too. It's a rather impressive attack.
Back in college, my (CS) department shared a student area with the students from the EE department, so naturally a friendly rivalry evolved.
There was a shared common area, and a private office for CS and EE each, both separated by lockable doors from the common area.
One day, we arrived to find that the EE department had left a taunting note on a desk in our (still) locked office.
At first we thought they airdropped it (since the office walls didn't reach all the way to the slightly domed ceiling), but we didn't think of the obvious: The office doors simply had their hinges on the outside. They straight up took the door off the hinges, and then put it back.