"Do Not Copy" Keys
Do Not Copy - what does it mean?
Many keys are emblazoned with Restricted, Registered, Do Not Copy, Patented, Design Registered, etc, so what does it all mean?
Firstly, it might not mean anything at all! Stamping a standard key with "Do Not Copy" does not mean anything. Your local hardware or shoe repairer will have the keyblanks and is allowed to supply duplicates to anyone.
Proper protection comes when the manufacturer of the keyblanks and key barrels have lodged Intellectual Property (IP) rights. Usually this is not a patent as such, but a 'registered design'. A patent is for how something works, a registered design is for how something looks, and conversely a trademark is for a symbol or slogan. They are all different forms of IP.
Registered design keyblanks are protected from manufacture, distribution and cutting for a period of 10 years (previously 16 years). Theoretically, once this time has lapsed the keys can be copied at the local hardware shop, but in the real world that rarely happens because they can't buy the keyblanks, and never will be able to.
The original manufacturer and their re-sellers have binding contracts that surpass the IP protection, continuing the real-world protection. Other manufacturers could theoretically manufacture the keyblank, but to produce them economically requires heavy investment in tooling, which has to be amortised in the price of each keyblank. If there were only a few keyblanks then it might be worth it, but there are hundreds of them just in Australia, simply not viable.
Of course all this IP stuff really only protects from mass-manufacture; any engineer with a milling machine and a spare day could produce a piece of metal to mimic a key, and the growing world of 3D printing only makes this easier. But then again RFID cards can be snooped and cloned much quicker and without requiring actual possession of the card.
Another advantage... Registered keys are produced to factory specifations every time. Instead of the local hardware shop tracing your existing worn key (on a $500 machine that hasn't been calibrated in months); your keys are produced on computerised CNC machines to exact dimensions at minute tolerances. This means no wiggling and jiggling badly "duplicated" keys, which wears out cylinders and tumblers, and the tumblers can be far more accurate because they don't need allowance for the dodgy $500 tracing machines.