Two-Keyed Lock: Difference between revisions

{{trope|wppage=Two-man rule}}

Sometimes one man can't be trusted so certain locks require two, or more, people to unlock, simultaneously. Maybe it's the keys to the world's destruction, or the kingdom's treasure, but whatever it is it's so important you know it must be good... or really bad. Hence the '''Two-Keyed Lock'''.

 

* The ''[[Portal (series)|Portal]]'' games use a few of these in both single-player and co-op. The former involve two buttons that need to be pressed within a short timespan of each other, and thus require having your two portal ends right next to them. (One of these is justified as an actual two-keyed security lock. The rest are just part of the tests.) The latter actually involve both players, and the game has thoughtfully included the ability to initiate a countdown that appears on the other's screen.

* ''[[Ōkamiden|Okamiden]]'' being based around partners has a plenty of these throughout the game where Chibi and his partner must stand on pressure pads to unlock doors or make bridges appear. One Notable example has a two-buttoned lock which is also a trap forcing Chibi to play through half the dungeon himself to gain the key to free his friend.

* The Thieves' Guild vault in [[Skyrim]] has one of these, with the keys being owned by the most powerful members of the guild. {{spoiler|No one realizes it's already been emptied by Guildmaster Mercer Frey, using a magical lockpick he stole from the goddess Nocturnal.}}

 

** The logic was that warheads mounted to missiles in either ground-based stations or in ballistic submarines are secure because of the two-man-rule interlocks, and PALs would risk a loss of readiness without significant security benefit. Actual (non-trivially-coded) PALs were (eventually) applied to small warheads - air-dropped bombs and ship/air-launched cruise missiles. Unlike ballistic missiles, these warheads can be stored or transported in a functional or semi-functional state, and thus can be used if lost or stolen. For these weapons, the two-man rule uses the PALs themselves - two officers must concur with the legitimacy of a nuclear launch order and release their portions of the PAL codes, or else the warheads cannot be armed.

* The Soviets had two launch keys and unlock codes held by the higher-ups (i.e. on shore) for their submarines. Now the case for US subs, but not always.

* Some Soviet nuclear missile silos had three blast doors, each needing three keys, and each key given to a different person. So a total of nine people were needed to actually get access to the missiles.

* In a much more mundane context, most of the rides at the local amusement park won't launch without both operators holding the go buttons, and they can still be locked out by ride sensors.

* Many industrial machines have two start buttons, but they are close enough to be pressed by a single operator so long as he uses both hands. The goal here is to ensure that both of the operator's hands are on the control box and not in the machine. Depending on the machine, there might also be a foot pedal.

* As detailed on ''[[60 Minutes]]'', the [https://en.wikipedia.org/wiki/Monastic_Republic_of_Mount_Athos Mount Athos monastery] has a vault which contains the order's most valuable books, documents, and artifacts, the door to the vault requiring several different keys to open, and a rule in place that says a monk is not allowed to hold more than one key at one time. Mike Wallace even described it as an archaic version of the PALs system listed above.