For as long as there have been haves and have-nots, the haves have sought ways to secure their valuables. History no longer remembers the inventor of the first lock, but invention of the first key is attributed to Theodore of Samos in the 6th century B.C., which leads to the suspicion locks have been around at least that long. In fact, crude locking mechanisms dating to about 2,000 B.C. have been found in Egyptian ruins.
The first devices resembling what we know today as door locks were discovered in the palace of Persian king Sargon II, who reigned from 722 to 705 B.C. They were large, clumsy devices made of wood. Nevertheless, they served as prototypes for contemporary security devices.
The first all-metal locks, probably made by English craftsmen, appeared between 870 and 900 A.D. in Rome. A row of bars of varying length, called tumblers, dropped into holes drilled through the horizontal bolt securing a door or gate. Only the person who possessed a metal bar fitted with pins corresponding to the tumblers could shove the bars upward through the holes, thus freeing the bolt.
No great advancements in lock technology occurred until about the 14th century A.D., when locks small enough to carry appeared. Traveling tradesmen used the so-called “convenient locks” to secure their money and other valuables.
Although padlocks were known to the Egyptians, Greeks, and Romans, the first combination lock didn’t appear until the 18th century. Until 1857, most banks used combination locks of some kind to secure their vaults. The secret to combination locks was to create complex series of letters and numbers that would frustrate anyone who tried to disarm the mechanism. The code for the combination lock securing the safe in the U.S. Treasury Department in Washington D.C., for example, required a lengthy series of letters and numbers that provided 1,073,741,824 possible combinations. Because cracking the code by systematically running through all the possible combinations would require 2,042 years, 324 days, and 1 hour (barring a lucky guess), the lock was considered burglar-proof.
Soon enough, enterprising criminals figured out combination locks had an Achilles heel: Robbers could hold a bank employee at gunpoint and demand he or she dial in the correct code.
In 1873, James Sargent invented what he called a theft-proof lock. The device combined a combination lock with a timer that would not allow the safe to be opened until a certain number of hours had passed, even if one knew the combination.
By the late 1870s, theft-proof locks were de rigueur in banks all over the U.S. Though they weren’t quite unbreakable — dynamite trumps almost any security measure — theft-proof locks thwarted more thieves than any previous mechanism.