Usually the advertised price must be honored, because it may have brought the customer to your store.

For prices displayed on the shelf-label inside the store the law is usually not that strict (YMMV), as a shop-owner can refuse sale on check-out (otherwise I could put a pricetag on e.g. a shopping-basket and the shop-owner would be legally required to sell me the basket...).

Besides, most shops I've seen (in Europe) already moved from Infrared communication to RF (NFC or proprietary), for centralized shelf-label management without handheld devices. So all this study (and the underlying reverse engineering of the IR-protocol) might do is probably accelerate the transition from IR to RF-based ESL...

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rimunroe 3 hours ago | parent | next [-]

> Usually the advertised price must be honored, because it may have brought the customer to your store.

This is not the case for groceries in Massachusetts at least. If there’s a discrepancy between the tag’s price and the scanned price the store must charge the customer the lowest of the two: https://www.mass.gov/price-accuracy-information

	▲	devilbunny an hour ago \| parent \| next [-]
		I suspect this law does not apply in cases of fraud. If not, simple tag-switching would be rampant.
	▲	stevekemp 2 hours ago \| parent \| prev [-]
		I recently learned that in some cases fines of mispriced goods were very low, leading to companies repeatedly failing tests - and over/undercharging their customers. https://www.theguardian.com/us-news/2025/dec/03/customers-pa... That seems shocking to me, but I guess I live in a country where the prices on the shelves are "final" (with no need to add taxes) and I think it would be immediately obvious if I'd been charged the wrong price for goods.

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teeray 2 hours ago | parent | prev | next [-]

It definitely varies by jurisdiction, but the register price always loses to any printed price in the US states I’ve lived in. This is a protection since retailers have used pricing mistakes to unfairly profit. Watch your receipt like a hawk at the dollar store[0]

[0] https://www.theguardian.com/us-news/2025/dec/03/customers-pa...

	▲	an hour ago \| parent [-]
		[deleted]

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master-lincoln 3 hours ago | parent | prev [-]

How is the transport medium changing anything?

To me this is about having protocols that are suitable so not anybody can write to these labels without knowing a store secret or using replay attacks.

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mschuster91 2 hours ago | parent [-]

> How is the transport medium changing anything?

it's mostly about efficiency. IR based, an employee needs to physically walk around. RF based, place a transmitter or two in the building and the system now works fully automated.

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master-lincoln an hour ago | parent [-]

Sorry about not being explicit. I meant how it changes anything security-wise.

With the same vulnerable protocol the RF system is as easy to attack with bigger consequences then it seems....

	▲	rickdeckard an hour ago \| parent [-]
		The RF system doesn't use the same protocol, it's a new protocol (to potentially hack and reverse-engineer). The early shelf-label systems were IR-based, sold in bulk and were programmed manually using handheld devices held against them. Most shelf-label solutions of today are part of a service-model, where gateways are mounted in the store to wirelessly update any label on price-change, often orchestrated remotely so store-chains can update all shops simultaneously.