Keys, in their current and most popular iteration, are easily duplicated (whether we want them to be or not). They are based on pins, springs, cams and valleys. The concept has been around for centuries. Moving ahead, we have key cards. These, too, with the right tools, can be easily duplicated. This idea is to create a key that is not easily duplicated, using crystals. The crystal material can be of many colors and have a variety of impurities. Different form factors can be used, cylinders, wafers, squares, etc. The concept is to have a laser shone through it and access granted or denied depending on the patterns and colors that come out through the otherwise. Multiple lasers will be used at different angles, truly utilizing the 3D geometry of the crystal's imperfections. Keys would be easy to make, but difficult to duplicate.
-- twitch, Feb 25 2018

Bakeable. A unique key based on random optical domains can be made simply enough.

The lock, of course, will need to "learn" each key; either the key needs to be presented to it, or the key's pattern needs to be uploaded. Either way, substantial storage capacity is needed. The best mechanical keys only have a million or so differs; electronic keys can easily provide almost unlimited options. A magstripe can carry 128 bits of data - 2 ^ 128 is 3.5 x 10 ^ 38 ...

The advantage of mechanical locks is they require no electrical power source. They can be inactive indefinitely, yet present the correct key, and they will function as intended.

This is an important consideration if the technical infrastructure of your civilization collapses, like yours is about to.
-- 8th of 7, Feb 25 2018


No spoilers!
-- 2 fries shy of a happy meal, Feb 25 2018


Awww, sorry ...
-- 8th of 7, Feb 25 2018


Tsh!
It's hard enough keeping them in their seats long enough for them to hit the snack-bar at least twice without people giving away all of the plot twists.
Please don't make me lock the writers back in their little hovel again. HR is still on my ass over the last time.

Philistines.
-- 2 fries shy of a happy meal, Feb 25 2018


Keys need to be fairly easy to duplicate. How often have you lost a key and needed a duplicate? So, what they really need is assurance that a "guess" key (equivalent to trying to "pick" a regular lock) will almost always be the wrong key.
-- Vernon, Feb 26 2018


No need to duplicate a key. Create a "learn yar key" key which will allow you to insert another key to learn it.
-- twitch, Feb 26 2018


Keys are also good for springing open the odd bottle of beer, or gouging out the eye of an otherwise determined attacker, where waving a crystal in font of them would have little effect.
-- xenzag, Feb 26 2018


//a "guess" key (equivalent to trying to "pick" a regular lock)// Not that this is relevant to the present discussion, but that's not how lockpicking works. When you pick a conventional lock, you are actually just nudging the "first" (ie, most heavily loaded) pin until you find its position; then the next-most, and so on. In effect, you open the lock one pin at a time, relying on imperfect manufacturing to allow you to do so.

The other common method of lockpicking is called bumping, and usually uses a manual or electric bumper. A very sharp, low-amplitude tap drives the top part of every pin upwards whilst leaving the bottom parts more or less stationary (like the middle ball in a Newton's Cradle), thereby opening up a wide gap across all the pins and allowing the lock to turn. This requires less (though not no) skill.

The weakness with super-duper electronic keys (like the one described) is not in the key/lock itself. Invariably, other ways are found to bypass the lock. As a for instance, hotel room safes usually have a user-set 4 or 6 digit code - not easy to "crack" from cold. However, most types have a "master override" code set by the manufacturer, and hoteliers often don't bother to change this code, so if you know a manufacturer's override code it will work on most of their safes. Another few types can be opened just by banging them the right way - the heavy-looking solenoid-operated bolt is mounted on a spring, and a sharp blow in the right spot will cause it to bounce, opening the safe. Many super-duper-almost- unpickable padlocks can be shimmed, etc etc.

But now I'm just rambling.
-- MaxwellBuchanan, Feb 26 2018


What I'm wondering, as been hinted at, how many duplicates for friends and family? Is it one unique crystal broken many times, <feel sad> many manufactured slices </feel sad> or the Dark Crystal option?

As soon as you mass manufacture, you've lost uniqueness, the straight key to the key lock pair.
-- wjt, Feb 27 2018



random, halfbakery