US Patent 7487653 Lock and key system with extra code combinations

A high security lock and key system with an increased number of code combinations wherein the blade of the key has a wave-like guiding surface at the side of the key blade which, upon insertion into an associated lock having a rotatable key plug, engages with one or more side locking tumblers in the lock cooperating with a side locking mechanism for locking the key plug against rotation. In order to provide an even higher number of possible code combinations, while preserving the overall dimensions of the locks and the keys of the system, an extra code level located at a longitudinally extending shelf surface, viz. at the upper boundary of the side material region where the wave-like guiding surface is cut at the side of the key blade. The invention also relates to a key and a key blade and to a lock for use in such a system.