LPL: 1452: Theory

So what is this lock for?

It returns one elapsed time and another elapsed time, presumably to return three time values (E1, E2, and E1-E2).

It's secured and tamper-proof, so it has to change hands.

If the box was going from point A to point B and then back to point A, then why wouldn't A synchronize one clock in the box with their own and send it off? Why not start it with a clock running? That's a three point affair.

The box has to end up in the hands of an authority of some kind instead of a one of the parties. Otherwise, the recipient could tamper with it. The first two points of travel aren't trustworthy.

It's stamped. If was worried about someone making a duplicate box, I would assume they could stamp whatever they wanted on it. It should be one box of many so that we know which is which. But the wristwatches in the design let us know it wasn't mass-produced. This was made for a small operation, like a small business or criminal enterprise.

It's from after the 40's, so it's not prohibition.

The groove and shackle. Why not a switch that JUST starts a clock? Why tamper-proof this box a ton, but leave whatever is being transported outside? On the other hand, why have that long groove at all if the shackle and groove don't serve a purpose? It could be easier to create a long groove than one just long enough for a thin ring to run through it, but let's assume its design is purposeful to its function It seems like something flat and hard would fit under the shackle. Flat so it will fit and hard so that it can't be wriggled out. If it's broken, it's intentional and the 'cargo' tamper-proofs itself. A "flatrod."

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So the first person creates their flatrod and shackles it into the groove. Technically, this marks when their flatrod is complete and not when they hand it off, but close enough.

The first person hands it to the second, who can look at (most of) one side of the other flatrod and then add their own.

The final product with two running clocks is delivered to an authority who verifies neither of the first people tampered with the device. They then remove the flatrods and compare the clocks inside to determine how long it's been since the second clock was started (delivery time), the difference between the two (second person flatrod generation time), and delivery time from person 1 to person 2 (the remainder of the first clock minus second person's flatrod generation time).

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The theory is that Person C sends the box to Person A. How long that takes doesn't matter. Person A adds a flatrod to the box and transfers it to Person B. Person B adds their own flatrod (perhaps based on information contained on the back of Person A's flatrod) to the box and sends it to Person C. Person C confirms the box number and monitors the time that the transit took from A to B to them and uses the flatrods.