In 1886, the year after the company opened its first shop outside France, on London's Oxford Street, Louis Vuitton adopted a single-lock system with two spring buckles that was billed as unpickable. Christie's credits Georges Vuitton, son of the founder, with the challenge that followed: he invited the escapologist Harry Houdini to escape from a locked Vuitton trunk. Houdini did not take up the offer.
The system meant one lock per trunk instead of several, and Wikipedia notes that each solid brass lock comes with an individual handmade key, so that a traveller needs only one key for all of their luggage. Christie's describes the lock as one of the brand's greatest innovations, now a hallmark of Louis Vuitton trunks.
The lock is still used on new trunks made in the house's workshops at Asnières, outside Paris, where trunks have been made by hand since 1859.