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The tiny chip that powers Montreal subway tickets

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Re: The tiny chip that powers Montreal subway tickets

#251

Post by lxgr »

GuB-42 wrote: post #87
mschuster91 wrote: post #42

> The Ultralight chip has a few features beyond a printed ticket, though. The chips are manufactured with a unique 7-byte identification code (UID). Moreover, the UID is signed, ensuring that fake UIDs cannot be generated. The problem is, they can be just as easily cloned . Your average Flipper Zero can do that. If you want actual security, you have to go for a challenge-response scheme - i.e. every card is provision…

> If you want actual security, you have to go for a challenge-response scheme Another option is to just store used UIDs in a database. In fact, you could do a system with only UIDs. For a single use ticket, validate the UID signature and mark it as spent the first time it is used, then every use after that will be denied. A card can be cloned, and it will work, once, it means one could steal a ticket by walking by an…

This scheme implies a low-latency, high-availability connection to a backend database. That's not easy to achieve in many transit system environments, hence the relative popularity of systems with some level of distribution.

Practical systems often are online these days, but only use that connection for eventual consistency style reconciliation.

> A card can be cloned, and it will work, once, it means one could steal a ticket by walking by and using appropriate equipment (not just a Flipper Zero as it is too short ranged) and use it before the legitimate owner does.

Even MIFARE Ultralight supports a basic password authentication scheme, where only legitimate readers know (or can derive) that password, so there a bit better protected against cloning than pure passive storage cards.

Re: The tiny chip that powers Montreal subway tickets

#252

Post by jeffparsons »

vundercind wrote: post #172
markus_zhang wrote: post #98

Earlier quoted context omitted.

I have found the same thing with my wife. I'm a technical person, but I'm extremely bad with tools and such, including the ticket thing. If no one shows me how to use it I'll probably figure out a way to insert it somewhere. My wife won't have any problem with this and other small tools. The same thing with IKEA: I always rely on the manual and just blindly follow the instructions, and gets very frustrated if the ins…

I’ve never seen them skip a step. Basically all other flat pack furniture I’ve ever bought has, but none of the dozen or so ikea items I’ve assembled. It’s part of why I only buy flat pack if it’s ikea, now.

I recently assembled two non-IKEA flat-packed items from two different vendors.

One left out details in the diagrams in each step that they had deemed irrelevant to that step. This apparent attempt at simplifying the instructions stumped me for ages because I kept thinking I'd oriented pieces wrong due to the number of holes in the picture differing from the number of holes in the physical thing.

The other had switched some parts since the instructions were made, and hadn't bothered to update the instructions. This was a bit more obvious, but still kinda irritating for someone like me who is uncomfortable with uncertainty when I believe certainty should be attainable.

Whatever else can be said of IKEA, their manuals and quality control are excellent. I think of them as the McDonald's of furniture — it's never the best product, but it's damn good for the price, and you know exactly what you're going to get.

Re: The tiny chip that powers Montreal subway tickets

#253

Post by lxgr »

rtpg wrote: post #203
bobthepanda wrote: post #129

Earlier quoted context omitted.

I don’t really see why a chip is needed at all for single use tickets. Those have existed forever and there are a plethora of non-chip options ranging from the simple holepunch to the optical printed barcode or QR code.

throughput, throughput, throughput. Magstripes tend to work not so well when you have the ticket in your pocket for a couple days, printed codes involve people futzing with cameras. You can use a sort of card ingestion system to line up a QR code or the like... but those things are complicated and break down a lot! You end up needing staff to constantly be opening it and unclogging it. This works alright if you have…

> Magstripes tend to work not so well when you have the ticket in your pocket for a couple days

How very true... SWIPE CARD AGAIN AT THIS TURNSTILE in glowing turqouise-ish dot matrix letters will be forever etched into my brain long after the Metrocard is finally gone.

Re: The tiny chip that powers Montreal subway tickets

#254

Post by lxgr »

mig39 wrote: post #60
bobthepanda wrote: post #3

This wasn’t super obvious to me until later in the article but this is about the single use tickets. Neat stuff, though I can’t say I love the concept of e-waste NFC.

The ones I've used in the Netherlands and Portugal are similar, but can be refilled. In Portugal, you pay extra for the initial ticket, but subsequent uses are cheaper, because you are using the same physical ticket.

I've actually always wondered what type of system the Portugese cards use: They don't seem to be based on anything ISO 14443 (or 15693) at least, since they don't react to my phone or external reader at all.

Re: The tiny chip that powers Montreal subway tickets

#255

Post by lxgr »

dheera wrote: post #101
b112 wrote: post #53

Earlier quoted context omitted.

I don't know how many times I've been in a city for a single day, or part of one, and have zero interest in spending precious minutes finding, buying, and returning a card. Just let me pay with coins, or a credit card in seconds, with no return work.

I believe Singapore's public transit does support tapping a credit card directly at the gates now, but there's an annoying step of having to register your card in advance on an app before it actually works. My guess is this might be because on-the-fly credit card authorizations still take too long. Waiting 3 seconds for an EMV contactless verification would seriously hold up the line at rush hour in a country where m…

That's odd. Most open-loop transit payment systems I know give new/unknown cards the benefit of the doubt, and put the card on a block list if it turns out to not be good for the fare that's eventually distributed to all readers.

Are you sure that's true? Their website says otherwise:

> Do I need to sign up for a SimplyGo account to use my contactless bank card for transit? You do not need to sign up for a SimplyGo account to use your contactless bank card for transit.

Re: The tiny chip that powers Montreal subway tickets

#256

Post by chii »

grishka wrote: post #230
CraigJPerry wrote: post #227

QR codes seem like a better ticket medium. This is like a 100 bytes, a qr code can be over 2kb This is a cheap plastic substrate with ink printing over the top. A qr code is just ink - or some other even cheaper printing process if you prefer. This needs a specific ticket technology supplier over the next 10’s of years. QR codes can be drawn on screens or printed on paper and you can change suppliers for every compon…

The problem with QR codes is that they are read-only. I don't know about Montreal, but Moscow public transport uses similar paper tickets, also Mifare Ultralight, except you can get them for different number of trips. When you use your ticket, the turnstile or validator would increment those one-way counters so that the next one would know how many trips you have left. You can't do that with a QR code without either…

it would be interesting to create a wipe mechanism to erase the existing QR code (may be a belt/sander, or a laser like those rust cleaning lasers), and print a new one on (may be even use the same laser as the wipe!).

Re: The tiny chip that powers Montreal subway tickets

#257

Post by lxgr »

zulban wrote: post #239
kumarvvr wrote: post #236

I am apalled at the crazy amount of waste this creates. Millions of tickets with chips inside them? My understanding is that they are one time use? In New Delhi metro, India, they used to use plastic tokens with these chips, but at the end of the journey, to exit the station you have to give the chip back. Nowadays, they use a printed QR system, and they have even gone paperless. I can buy the ticket with my mobile a…

The fact that they cost just a few pennies each is a reflection of how little waste is occurring. If waste bothers you, focus on something worthwhile like canceling just one airline flight. Lifetime of a plastic opus card may even be more wasteful, by mass of plastic and chip, if not used extensively. For example, one time use is often for tourists, where a full chip opus would be very wasteful indeed.

> If waste bothers you, focus on something worthwhile like canceling just one airline flight.

That's just whataboutism: If there's an alternative way of solving the same problem that generates less waste, why not use it?

I find the contactless coin form factor for single rides quite clever personally, and I don't see any downsides compared to paper single-use tickets (other than that validators and gates need some storage container to collect them, which could be tricky in buses).

Re: The tiny chip that powers Montreal subway tickets

#258

Post by lxgr »

kumarvvr wrote: post #236

I am apalled at the crazy amount of waste this creates. Millions of tickets with chips inside them? My understanding is that they are one time use? In New Delhi metro, India, they used to use plastic tokens with these chips, but at the end of the journey, to exit the station you have to give the chip back. Nowadays, they use a printed QR system, and they have even gone paperless. I can buy the ticket with my mobile a…

I find the plastic tokens quite clever, but QR codes are not a great option for mobile ticketing at transit gates: Often it takes people forever to pull up the code in the right orientation and dial up the brightness enough for the scan to work. Not something I love to deal with when I want to catch a train.

Re: The tiny chip that powers Montreal subway tickets

#259

Post by grishka »

chii wrote: post #256
grishka wrote: post #230

Earlier quoted context omitted.

The problem with QR codes is that they are read-only. I don't know about Montreal, but Moscow public transport uses similar paper tickets, also Mifare Ultralight, except you can get them for different number of trips. When you use your ticket, the turnstile or validator would increment those one-way counters so that the next one would know how many trips you have left. You can't do that with a QR code without either…

it would be interesting to create a wipe mechanism to erase the existing QR code (may be a belt/sander, or a laser like those rust cleaning lasers), and print a new one on (may be even use the same laser as the wipe!).

If you really want a system that uses optical scanning and allows one ticket to be used multiple times, just make sure that there's enough room on the ticket for one QR code per trip. When validating, you'd print a new code in free space. You can also either print something over the old one to invalidate it, or just leave it and let the system itself figure out which of the codes is newest.

Re: The tiny chip that powers Montreal subway tickets

#260

Post by kalleboo »

I recently learned that you can just give a printing company a hundred bucks or so and have custom NFC cards printed for you, you don't actually have to be a big transit agency with an ongoing contract for millions of the things and a custom JavaCard NFC application or w/e coded for you.

I used this knowledge to replace the QR code membership card to my friend's bar with an NFC card version, it looks really cool in your wallet compared to all the flimsy paper stamp cards from the other bars.

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