What are ancient locks and keys made of and what are their principles?

Three-reed lock is a traditional lock in China, which first appeared in the Han Dynasty and retired from the historical stage in the middle of the 20th century. Three-spring lock mainly uses two or three plate-shaped copper sheets to realize the functions of sealing and opening. Keyholes can be made into different shapes, and different keys can be made according to the shapes. The key changes a lot, the confidentiality is strengthened, and the use range is wider, so it is called "wide lock". After the Tang Dynasty in China, the three-reed lock was continuously improved and perfected, and more than 100 styles appeared. Some locks also use technologies such as secret door, orientation, two-opening, keyless, and text password, which further increases the difficulty of unlocking.