The laws Australian changed back in 2018 to allow the government to break the encryption on software (and apps) that use it. In essence, to create a backdoor. Now, Five Eyes nations plus Japan, India call for Big Tech to bake backdoors into everything.
You don’t have to go back too far in history to find the creation of a similar backdoor and the problems it creates. The TSA (aka Transportation Security Administration), according to some sources they would cut off the locks to inspect baggage and had received 3,500 complaints in 2011. So TSA had a special set of locks manufactured with a set of eight master keys that could open them.
However, due to a photo of the keys getting out, people recreated them using 3D printing. By 2016 The last TSA master key has been hacked, but the TSA Doesn’t Care That Its Luggage Locks Have Been Hacked.
This form, of security relies on people not knowing the secret. Basically, the phrase is Security through obscurity. It’s a simple trick to ass these ideas to your game.
A backdoor is just a door, it maybe in software or cyberspace, but it’s still a door. So you can use it like one. To access the secrets hidden inside a backdoor will have a key to open it. During the Cold War, trusted agents would courier the high security encryption keys across the world. The Briefcases would never leave the agent’s sight and be attached usually by handcuff.
The technology to do so may b more complex, but keys can be copied. There are a bunch of Spy movies, where the key must be copied to allow access to the files, hidden images, or whatever.
Treat it just like a thief uses custom tools to pick a physical or electronic lock. A Netrunner or Hacker uses software tools to break the lock. Knowing this could happen, what will an organization (corporate, criminal, or governmental) do to keep the secret.
In summary, treat this MacGuffin to help draw the story forward. Or as a hot potato that the PCs don’t want.