If you ever listen to people who really love locks talk about locks they all seem to say one thing. "All locks are pickable [or attackable]". This just means that this particular lock is abnormal and most lock-people don't have the experience to attack it, not that it is secure.
If you are semi-interested in locks, I really recommend listening to Schuyler Towne talk about locks. He's one of those people who is very passionate about what he does in a way that interest in locks really rubs off onto you in a really educational and relatable way.
The other thing to keep in mind is that a system is only as secure as its weakest link. You might not be able to pick this lock, but if you really want to get inside, a crowbar might work.
Better doors are available, especially in countries with terrorism problems. See, for example, Israel's "www.rb-doors.com". Their residential doors look like ordinary doors, but when the door is locked, seven bolts come out four sides, like a vault door.
The key says "FÜR HERVORRAGENDE LEISTUNGEN" on the left, German meaning "for outstanding performance", a phrase commonly used to honor something that is very good but still did not win the award. On the right is "SALON DES INVENTIONS DE GENEVE", French for "International Exhibition of Inventions Geneva" [1]. So it did probably well in the "1991 GOLDEN AWARD" but did not win. On the metal it just says "SOFT KEY", "PATENT" and the company logo, the back side of the plastic part contains the company logo and "PATENT" again and another round logo with 12 stars and something in the middle I am unable to identify.
"If you want to open one of these, I made a diamond pick out of thick plastic from an engine oil bottle. It was flexible enough to bend at the curved keyway, but if you were careful, they were still strong enough to manipulate the pins. The shank of the plastic pick will need to be wide enough to give some strength to the pick.
Also made a back-up key from a milk jug that lasted for one opening, and another from the oil bottle that lasted for four openings. The picks an plastic keys wear out quickly."
Once you have a pick that can follow the curves like the key, picking it should be just as simple as any other lock.
You certainly couldn't make the pick out of street-cleaner bristles! It isn't clear if you could do that with some other material (I'm thinking of a thick kind of flexible wire) or if you would need to make a similar type of chained pick. Depends on the force required I guess.
Yeah, one of the obvious means is key duplication; even the key guide could be cut into pieces, re-attached with sticky tape, and fed in with a shim feeler.
Is there a rigid section penetrating into the lock channel at all? It seems like this lock would be especially prone to broken keys from over torquing.
If you can't see the beauty of engineering here, nor have your mind race for any possible ways to defeat this - I don't know what to tell you. I've never seen anything like this before and I literally started laughing out loud at my desk when I saw that chain-link key come out. I can picture the lock-picking community drooling over a chance to find a way to defeat this thing. It's like one of tptacek's hacker challenges, but for mechanical-engineer types or something.
I'm sure whatever picking-solution is used, it will make me grin from ear-to-ear thinking: "that is the most clever thing I have seen in a long time"
If you are semi-interested in locks, I really recommend listening to Schuyler Towne talk about locks. He's one of those people who is very passionate about what he does in a way that interest in locks really rubs off onto you in a really educational and relatable way.
Here's a longer talk about the history of locks by him from 2012. It's a great place to start. https://www.youtube.com/watch?v=jqjacHSTd48&list=UUBDpLXSbLH...