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Comment by nl | Hacker News Reader

I think this is an interesting but my immediate question is how much are the color matrices affected by normal shipping?

If your intention is to be able to detect tampering during shipping but shipping always causes some disturbance then it probably deserves some discussion?

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Vacuum packing small grain-like things like coffee beans/grounds or rice creates a surprisingly sturdy result. I'd be surprised if you could actually move much around without also piercing the plastic.

I've bought products packaged like this before and it's a really odd sensation feeling the bag go from effectively a single solid object to a bag of mush as soon as you release the vacuum.

This effect is used in adjustable casts (these modern plastic ones that you get when you break your foot) and vacuum stretchers for people with a suspected spine injury(+). They’re essentially a bag filled with tiny foam pellets that adjusts to your foot/body shape and turn rock solid once you pump out the air.

(+) https://www.rusunsafety.com/VacuumMattressStretcher/

I'd run across a demonstration of this somewhat recently. I believe it was a video explaining transitions between free-flowing and locked particles, though I don't recall specifically where, and was unable to find it looking for a few minutes just now.

That said: yes, vacuum-sealing good such as beans or coffee grounds provides a surprisingly solid chunk. Releasing the vacuum instantly changes the properties of the mass.

The vacuum packing is tight enough to prevent any significant motion.

Is it? I'm doubtful.

I regularly vacuum pack clothing when I travel and things move enough to change creases even in my carry-on luggage. I'm skeptical that it won't be disturbed in regular shipping unless specific measures are taken.

I used to buy vacuum packed peanuts, there was practically zero chance that they would move around. I also remember that when vacuum packing beddings the result was hard like a brick.

The authors should test if this is actually the case or not.

I think it would be fun to test this with a few people. Let’s vacuum pack some beans and ship them between each other. Sisterhood of the Shipped Legumes.

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I can confirm it. I have a commercial vacuum packing machine, and a bag of rice sealed in it becomes a brick. You can't displace a grain of rice without damaging the vacuum. I doubt that a laptop inside this bag would survive it.

A commercial vacuum packing machine may be stronger than a normal home vacuum cleaner, which the article mentions. Fewer people have access to a commercial machine.

Yeah I was talking about the home vacuum cleaner method. The article mentions that first, but it does go on to mention vacuum packing machines too.

I could see vacuum packing machines possibly working for this.

If I were tasked with dealing with this I would disturb the rice every single shipment, and then let the item continue to its destination.

When every single shipment shows sign of tampering I would expect them to give up on this method.

If you were disturbing every single shipment, I would assume someone was tampering. Once I find a shipping route where none of the items were disturbed, I would know it is secure.

Right, if you are worried about covert tampering and every shipment shows up tampered, you have proven that someone along the shipping route is tampering. You react by distrusting any packages that were previously shipped without anti-tamper protection. And you find a different shipping route. This is costly, but it's a reaction to a threat you can prove to be targeting you.

The tamperer is probably better off not tampering with packages, unless they can do so in a plausibly deniable way.

> I would disturb the rice every single shipment

Increasing attacker costs = success.

It would also increase defender costs, if the defender has to throw out our re-ship some perfectly good hardware every time some of the rice it was packed in was disturbed.

Decoys are a tried and true response to surveillance, with decades if not centuries of best practices.

The shippers would probably find a different way to ship things.

Negative, do not change. While you are incurring a cost to the attacker keep it as is. Ship nulls regularly AND find another method.

Exactly. I would imagine any sort of substantial impact (common in shipping) would shift around some of the pieces.

I believe they attempted to address this via vacuum sealing and cascading bags (if I understood the article).

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