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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

#301

Post by matsimitsu »

sverhagen wrote: post #298
hgomersall wrote: post #294

Earlier quoted context omitted.

I don't think the suggestion is the QR code contains the ticket info, but that the QR code is the unique tag into the back end virtual ticket system. 1 to 3 are not relevant in that context, and 4 isn't borne out in my experience with modern readers (they're used in the bar code mix at parkrun and they read time is vanishingly fast with a smart phone, generally better than barcodes). The number of bits might increase…

> and 4 isn't borne out in my experience To bolster your point, aren't there whole countries where stores and street sales float on top of QR codes?

In China, QR Codes are used for public transport too, and I found them just as fast as NFC readers (and faster than the slow readers used by the NS in The Netherlands)

Re: The tiny chip that powers Montreal subway tickets

#302

Post by defrost »

sverhagen wrote: post #298
hgomersall wrote: post #294

Earlier quoted context omitted.

I don't think the suggestion is the QR code contains the ticket info, but that the QR code is the unique tag into the back end virtual ticket system. 1 to 3 are not relevant in that context, and 4 isn't borne out in my experience with modern readers (they're used in the bar code mix at parkrun and they read time is vanishingly fast with a smart phone, generally better than barcodes). The number of bits might increase…

> and 4 isn't borne out in my experience To bolster your point, aren't there whole countries where stores and street sales float on top of QR codes?

Yes- of interest:

China's Big Tech companies taught Asia to pay by scanning QR codes, but made a mess along the way

https://www.theregister.com/2024/06/17/asia_qr_code_obsessio...

Re: The tiny chip that powers Montreal subway tickets

#303

Post by grishka »

grishka wrote: post #235
chgs wrote: post #123

Mifare is what’s been used in London’s Oyster cards for 20 years (not the ultralight ones mind), and Hong Kong for even longer. However oyster really is in its way out for most uses. contactless and especially a phone is far more convenient for non season use, and far less wasteful.

Isn't Mifare in different forms a de-facto standard for NFC subway tickets around the world? St Petersburg uses Mifare Classic (and tokens), Moscow also uses Mifare Classic for the refillable Troika card and Mifare Ultralight for disposable ones, Dubai "nol" card is a Mifare Desfire, Los Angeles "tap" card is a Mifare Classic, and, yes, the London Oyster is a Mifare Desfire EV1. Yes I actually went through my stack o…

Update: some of those that I labeled as Mifare Classic are actually Mifare Plus, it's just that the app I'm using didn't distinguish them ¯\_(ツ)_/¯

Re: The tiny chip that powers Montreal subway tickets

#304

Post by mav3ri3k »

grishka wrote: post #288
mav3ri3k wrote: post #284

Earlier quoted context omitted.

I am not sure which part is impractical. In India we already use QR code for metro tickets. The system design is definitely different from one mentioned and mimics more of how airport tickets work.

How does the system know that the ticket was already used? The thing with plane and long-distance train tickets is that you buy them for a specific route. So all the checking only needs to be done at your departure station/airport, the code for which is encoded in the ticket, and the rest of the system doesn't need to know anything about it. But you can't do that with city transport. When there aren't multi-use ticke…

Fair enough. I went through qr code of my previous metro ticket to see what info they encode. It is non standard so there were - some hashes - type of ticket, in my case single use, - time of issue, - valid upto time, approx 10hrs, approx journey time was only 30 min - ticket id - I could not directly see source/destination address, but it is my hunch that atleast the destination address is encoded

Now this one time ticket needs to generated before entering the metro station and the qr code is scanned at * both entry and exit*.

I think the entire system works on daily rotating ticket id validated using unique hashes where a ticket validity period is tracked. I think this should be enough to ensure non-reuse of same ticket.

The caveat is, I have always only bough one time ticket which is the only mode allowed in qr. For daily traveller's, they need to buy token/card which is NFC based.

Re: The tiny chip that powers Montreal subway tickets

#305

Post by The_Colonel »

CraigJPerry wrote: post #293
rswail wrote: post #289

Earlier quoted context omitted.

I've worked in public transport ticketing for the past 30 years including the first system outside Japan (Hong Kong's Octopus). The problem with QR codes: 1. If they're printed, they can be copied. 2. "Dynamic" QR codes can be screenshot. 3. They're read-only (by definition) 4. Readers are slow, require good orientation by the user. NFC is good because it's read/write, has a ~10cm range, the larger cards can hold up…

1. Thats ok. If you’re expecting your rfid tokens not to be copied just because it seems inconvenient to do so, you’re in for a surprise! Your ticketing system cannot assume tickets in any form cannot be replicated- they can be and if you introduce such a vulnerability in your system, you will lose revenue 2. As per 1, no issue 3. That’d be a great feature if true, I’m all for immutability. However , qr codes can be…

> Your ticketing system cannot assume tickets in any form cannot be replicated- they can be and if you introduce such a vulnerability in your system, you will lose revenue

Yes, the question is not whether such system would be abused, but how much. But this is in the end what businesses care about.

Will QR codes be abused more than NFC chips? Likely yes.

Will it produce a larger financial loss than the cost of the NFC chips?

Can I mitigate these losses by a centralized validation system (each terminal needs a network connection with low latency guarantees)? Sure, but how much will it cost?

Re: The tiny chip that powers Montreal subway tickets

#306

Post by gsa »

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…

> there's an annoying step of having to register your card in advance on an app before it actually works.

Did this change recently? I travelled a little over a year ago and my Wise card worked right after I landed at the Singapore airport.

Re: The tiny chip that powers Montreal subway tickets

#307

Post by socksy »

jhugo wrote: post #241
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…

When I lived in Shanghai 6 years ago they were trialling QR for the metro. It was really bad, always huge queues with people struggling to get the right angle/illumination/whatever to make it scan. I’ve never seen similar issues with contactless methods and in fact I think SH subsequently moved to them. The amount of data stored seems pretty trivial to scale if necessary.

When I was in Shanghai this year I used a metro QR code via AliPay, and it seemed everyone else did too. There didn't seem to be any issue with scanning them so I guess everyone got used to that. There was however a queue by the security theatre bag scanning device at every single ticket gate.

Re: The tiny chip that powers Montreal subway tickets

#308

Post by socksy »

marssaxman wrote: post #69
justusthane wrote: post #21

This is fascinating. We were just in Europe where we experienced these tickets for the first time. I had trouble with them; I was trying to figure out how to scan them because it never occurred to me that they might contain an NFC chip. My wife, on the other hand, who is not at all technical, took it for granted that you would tap them and immediately figured it out intuitively.

That's funny - I'm sure I would have shared your confusion, as all tappable objects in my world are made of plastic. I wonder how your wife thought of it?

The ones in Athens are thin white cards and as such easy to see the aerial through it. Additionally there's no slot to put it through, and a big tap surface at each gate with the RFID logo with someone tapping a card on it.[1] I think it would be hard to miss for anyone familiar with the concept of tapping cards.

[1] https://www.athenstransport.com/english/tickets/

Re: The tiny chip that powers Montreal subway tickets

#309

Post by xaduha »

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…

> QR codes seem like a better ticket medium.

If it was a short-lived QR code generated on your phone, then maybe. But the whole point of MIFARE Ultralight EV1 cards is that they can't be cloned. It's for repeated use, not for printing and using once.

Re: The tiny chip that powers Montreal subway tickets

#310

Post by sofixa »

mjg59 wrote: post #210
amluto wrote: post #180

Earlier quoted context omitted.

I’ve occasionally gotten to watch transit workers open up and service the magnetic stripe card readers in the BART. Those things are complicated . It may well cost less to outright replace a contactless reader module on a fare gate than to service a magnetic stripe ticket machine once. Even an Adafruit PN532 board is only $40.

BART stopped accepting paper tickets last year, presumably because of the complexity (not just the ticket barriers, but also the fare machines and add value machines that also had to handle them): https://www.bart.gov/news/articles/2023/news20230911

Yeah, they moved to a native integration with Apple/Google/Samsung Wallets, and Clipper cards as a backup (but they really try to discourage them, at least for tourists).

The cool thing is that their thing doesn't work with all Android phones for an unknown reason (various people from the transit agency said "oh Android? Yeah it doesn't always work with Android"), which you have no way of knowing before topping up money and trying to use your phone.

If anyone is curious, it was a Xiaomi Redmi phone, a midrange one that has no issues paying over NFC. A OnePlus next to it with the same Android version worked just fine.

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