The Byzantine Monks of Mt. Athos have a multi-key security system protecting their invaluable religious relics.
It is a 4-Key system with each unique key being held by a different monk.
CBS 60 Minutes recorded this amazing behind the scenes footage of the multi-key system in actual use.
https://youtu.be/J1lvruy-j2c?t=640
They’re under lock and key. It’s not a new security system, but it works. Normally it takes more than one monk to unlock the ancient door, because no one monk is allowed to have all four keys at the same time. It is sort of a medieval version of the nuclear launch control.
https://www.cbsnews.com/news/mt-athos-a-visit-to-the-holy-mountain/6/
Nothing new under the Sun.