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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

#291

Post by ascorbic »

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…

Japan uses FeliCa for its integrated transport cards (I just read an Osaka Metro ICOCA card with NFC Tools to check). This is used by quite a few systems around the world, including Hong Kong's Octopus.

Re: The tiny chip that powers Montreal subway tickets

#292

Post by grishka »

caf wrote: post #279
kens wrote: post #2

Author here for all your NFC chip questions :-)

I'm curious about how the unique ID is programmed into each chip. Presumably all the chips on the wafer come out identical - at which point in the process are they individually selected and given a unique personality? Is it done with direct electrical contact that is then fused off, or using the near field link?

Maybe some kind of custom NFC command that writes the UID into the EEPROM and sets a flag that it's now read only?

Re: The tiny chip that powers Montreal subway tickets

#293

Post by CraigJPerry »

rswail wrote: post #289
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…

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 defaced easily, hopefully the built in checksum defend against that. a more likely threat your system needs to defend against is that new qr codes can be generated extremely quickly

4. Both systems are the same speed, both systems require accurate targeting by the user, an rfid token slightly askew of the reader will not read since it won’t be able to influence / absorb the generated rf - most of these systems work by providing power to the rfid token and it communicates back not by transmitting its own signal but by exerting influence on the signal it’s receiving. It’s a very very low power interaction and very sensitive to positioning

A better problem than 4 is that you entail staff overheads with a visual system to keep them clean.

Read / write is a bad feature, you will lose ticket sales.

Recycling these is not practical. Direct reuse risks jamming the vending machine (used tickets end up subtly bent, very hard to reliably deal with), actual recycling isn’t viable, the energy required and emissions produced exceed that of creation of a new card from raw materials.

Re: The tiny chip that powers Montreal subway tickets

#294

Post by hgomersall »

rswail wrote: post #289
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…

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…

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 the difficulty if capturing the code, but I would very surprised if a fast, robust system can't be built.

The huge disadvantage of NFC in this context is the electronic waste necessarily produced.

Re: The tiny chip that powers Montreal subway tickets

#295

Post by kens »

caf wrote: post #279
kens wrote: post #2

Author here for all your NFC chip questions :-)

I'm curious about how the unique ID is programmed into each chip. Presumably all the chips on the wafer come out identical - at which point in the process are they individually selected and given a unique personality? Is it done with direct electrical contact that is then fused off, or using the near field link?

Since they need to probe each die to test it on the wafer, they set the UID at the same time. According to the datasheet, "These bytes are programmed and write protected in the production test."

Re: The tiny chip that powers Montreal subway tickets

#296

Post by windex »

TeMPOraL wrote: post #164
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…

> The same thing with IKEA: I always rely on the manual and just blindly follow the instructions, and gets very frustrated if the instructions miss one step. Thing I figured out assembling IKEA stuff in the past few years: if it seems like they skipped a step, look carefully at the details in pictures. Perhaps use a magnifying glass. There's going to be only one way to get from step N to step N+1, and all the informa…

Ikea also doesn't use Philips screws. They have pozidriv screws and need pozidriv bits if you dont want to strip the screw heads. I learned the hard way.

Re: The tiny chip that powers Montreal subway tickets

#297

Post by user_7832 »

Fej wrote: post #266
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…

NJ Transit uses QR codes for all train tickets and it works well enough. It's not quite as seamless as a tap card but NJT has moved largely to mobile ticketing and they're in the odd position of having to scan tickets both at turnstiles and by train crew (handheld scanners); cards would be awkward in the latter case. The paper tickets used to have magstripes but once they adopted QR codes for the mobile app, the tick…

> cards would be awkward in the latter case

Do you mean it would be hard for staff to scan cards? Here in the Netherlands both qr and cards (travel cards + bank cards) can be used at stations, and are read by the staff on the train.

Re: The tiny chip that powers Montreal subway tickets

#298

Post by sverhagen »

hgomersall wrote: post #294
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…

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?

Re: The tiny chip that powers Montreal subway tickets

#299

Post by Arch-TK »

Interesting discussions in the comments regarding reuse, waste, QR codes, etc.

Worth bearing in mind that in the UK train stations have mixed NFC, QR and magnetic readers. The ones which are the least reliable are the magnetic readers which operate on paper cards. The NFC readers are used for pre-paid ticket cards and credit/debit cards. The QR scanners for so called "E-Tickets".

I don't really ever see anyone have problems with the QR tickets (they're static and distributed as PDF or pkpass). Likewise with NFC. Only the paper magstripe cards commonly cause problems.

Meanwhile in the Shanghai metro they use chip coins. Small, reusable and NFC.

I think these paper NFC things are a unique combination of non-reusable, prone to damage, prone to jamming.

But they are cool.

Re: The tiny chip that powers Montreal subway tickets

#300

Post by chii »

grishka wrote: post #259
chii wrote: post #256

Earlier quoted context omitted.

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.

i'd assume the QR code would contain a record of the transactions, but yea, i hadn't thought about multiple trips that overlap.
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