That's how this remarkable design is described by lockpicker John Coulter, whose efforts have been stymied by its peculiar design: instead of being a straight, flat piece of metal, the key is a flexible chain similar to a watch strap, housed in a hard slip-casing that allows it to be inserted into the snaking design of the lock itseld.
Coulter's been sleuthing it's origins with the help of commenters at his YouTube channel. Dan Neuenswander found a patent, awarded in 1992 to Yun-Tung Hsu, who appears to be a prolific inventor in the field.
The following illustrated is marked in the patent as prior art–meaning it is an acknowledgement of an earlier design–but it illustrates the basic concept well:
Hsu's implementation is rather more elaborate, providing the details of mechanical implementation.
MrMonkeyMonk: "This looks like a german lock to me. If you want to know more, it seems to have been awarded by the VDI, which is a german engineering club, in 1991 via the Carl-Eduard-Schulte-Stiftung. It seems to have been a diploma project, but I can not figure out who did it. Maybe you want to call the VDI: http://www.vdi.de/3129.0.html
Dan Neuenswander found the patent of this lock: https://www.google.com/patents/US5131247?dq=5131247&hl=tr&sa=X&ei=PSlCVIyKKMTfPZKdgMAO&ved=0CB4Q6AEwAA