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> d) The only thing that should (ideally) be stored on any RFID chip is a unique number I disagree. This is basically where RFID has its benefits. Transport fo

> d) The only thing that should (ideally) be stored on any RFID chip is a unique number I disagree. This is basically where RFID has its benefits. Transport for London has the Oyster card, which I'm pretty sure is "electronic cash", i.e. your balance is stored on the card. This allows the system to work without the huge point of failure that is a central database and the connections to it. They have millions of people passing though thousands of checkpoints, many of them on moving busses. The infrastructure needed to make sure that every single one of these checkpoints can at any given time instantly run a transaction on the central database vs. having autonomous readers that just needs to upload their log every once in a while is huge. It's basically the difference between mainframes/dumb terminals and P2P. The problem is that RFID implementers have been cheap with the security on those chips. It's pretty simple to make a secure setup (famous last words....) tried and true ideas from cryptography (public key infrastructure etc..) but these call for more expensive chips, and when the choice is between expensive crypto that works and cheap security-through-obscurity that works until a grad-student is bored for the summer, you're going to go with the latter, of course.

moe 16y ago
Transport for London has the Oyster card, which I'm pretty sure is "electronic cash", i.e. your balance is stored on the card. I wonder why people rolling out such systems never seem to see the obvious(?) writing on the wall: 1. Someone comes up with an "infinite balance"-hack. 2. Infinite balance cards are sold on a growing scale. 3. Transport company is forced to apply expensive bandaids to contain the problem. Moreover I don't understand why they don't simply leverage the device that everyone already has in their pocket - the cellphone. The infrastructure would likely cost an order of magnitude less (barcode scanners like in airports, or bluetooth) and more importantly the system would be rather easy to make cryptographically secure because it's all in software. "But what if I forgot my cellphone at home" - well, same thing if you forgot your RFID card at home.
- mseebach 16y ago
  > I wonder why people rolling out such systems never seem to see the obvious(?) writing on the wall: The writing isn't at all obvious, otherwise they wouldn't have come up with it. I guess they've come to the conclusion that forging Oyster cash is similar to forging paper ticket or real cash. I don't know exactly how the Oyster card is implemented, but if it has some level of transaction log trail (however asynchronous), it's possible to detect forgeries (if you've only ever deposited £20, but since spend £100, you're cheating). > Moreover I don't understand why they don't simply leverage the device that everyone already has in their pocket - the cellphone. Scanning a barcode on a cellphone screen has three problems: 1: There are still loads and loads of cellphones not reliably capable of displaying a scannable barcode. 2: Barcodes are 100% copyable and include 0 cryptography - they have the same security as a barcode printed on a piece of paper, which, incidentally, is what they replace in airports. 3: A barcodes is read-only and requires online access to verify and record the transaction which is not feasible on the scale required for TfL. Bluetooth has similar problems: 1: While most phones might be BT equipped, developing and supporting software for enough different phonemodels is very complex. 2: BT is designed for communication between specific devices, not a "class" of trusted devices. You can't trust all TfL checkpoints under one, so you'd have to navigate some sort of interaction every time you check in and out of a station/bus. Also, this interaction is different for each phone type = support hell. 3: BT is long range, compared to an RFID card. Sure, an RFID card might be skimmed from a difference, but it's easy for a reader to tell the card directly on the reader from every other card in the room. No so much for BT. The solution including cellphones we need is NFC, which is basically RFID that can leverage the processing power of the cellphone. It just doesn't exist on very many phones yet.
  - moe 16y ago
    Barcodes are 100% copyable and include 0 cryptography That doesn't have to be case, which imho invalidates the rest of your points. It's perfectly doable to issue tamper-proof tickets in the form of cryptographic signatures. So you could, for example, on a website order a barcode that encodes "This ticket valid between 10:00-18:00, on route section X, and belongs to Mr. John Doe". Obviously someone could copy and re-use that very barcode but you have the same problem with RFID tokens, unless there's some sort of centralized validation going on. Which is, btw, actually much easier to implement than you make it out to be, considering you'll have a hard time finding a train-station without GSM coverage nowadays. I do agree with your concerns that not everyone has a phone capable of displaying these codes, yet, but it's a matter of years until that will be the case. During then you'll need the old paper tickets as a fallback - but that's the case with any new technology, it's not like you could flip the switch with RFID over night either. Likewise Bluetooth may indeed be the wrong tool for the job, personally I'd favor the barcodes that seem to work out well enough on airports. And finally, the development effort for making the software work all phone platforms is negligible. Again, the Airlines have demonstrated it can be done, and when you compare it to the effort required to rollout an RFID solution including the hardware then I'd bet the barcode approach is actually easier to do. So. This, for once, is a problem that would be fairly straightforward to solve with technology. I can't help but assume this massive gravity towards more expensive and inferior solutions is mostly a result of lobbying. Obviously there's much more money to be made by handing out physical tokens and then enjoying the benefits of a ridiculously expensive support contract as you pile bandaid over bandaid...
- doki_pen 16y ago
  This already has happened in Boston. http://joshuamcginnis.com/2008/08/09/wow-how-to-hack-boston-mbta-cards-for-under-15/ http://joshuamcginnis.com/2008/08/09/wow-how-to-hack-boston-... It's really shocking that people think storing MONEY on a card that everyone has read/write access to is a GOOD idea.

moe 16y ago

Transport for London has the Oyster card, which I'm pretty sure is "electronic cash", i.e. your balance is stored on the card. I wonder why people rolling out such systems never seem to see the obvious(?) writing on the wall: 1. Someone comes up with an "infinite balance"-hack. 2. Infinite balance cards are sold on a growing scale. 3. Transport company is forced to apply expensive bandaids to contain the problem. Moreover I don't understand why they don't simply leverage the device that everyone already has in their pocket - the cellphone. The infrastructure would likely cost an order of magnitude less (barcode scanners like in airports, or bluetooth) and more importantly the system would be rather easy to make cryptographically secure because it's all in software. "But what if I forgot my cellphone at home" - well, same thing if you forgot your RFID card at home.

mseebach 16y ago
> I wonder why people rolling out such systems never seem to see the obvious(?) writing on the wall: The writing isn't at all obvious, otherwise they wouldn't have come up with it. I guess they've come to the conclusion that forging Oyster cash is similar to forging paper ticket or real cash. I don't know exactly how the Oyster card is implemented, but if it has some level of transaction log trail (however asynchronous), it's possible to detect forgeries (if you've only ever deposited £20, but since spend £100, you're cheating). > Moreover I don't understand why they don't simply leverage the device that everyone already has in their pocket - the cellphone. Scanning a barcode on a cellphone screen has three problems: 1: There are still loads and loads of cellphones not reliably capable of displaying a scannable barcode. 2: Barcodes are 100% copyable and include 0 cryptography - they have the same security as a barcode printed on a piece of paper, which, incidentally, is what they replace in airports. 3: A barcodes is read-only and requires online access to verify and record the transaction which is not feasible on the scale required for TfL. Bluetooth has similar problems: 1: While most phones might be BT equipped, developing and supporting software for enough different phonemodels is very complex. 2: BT is designed for communication between specific devices, not a "class" of trusted devices. You can't trust all TfL checkpoints under one, so you'd have to navigate some sort of interaction every time you check in and out of a station/bus. Also, this interaction is different for each phone type = support hell. 3: BT is long range, compared to an RFID card. Sure, an RFID card might be skimmed from a difference, but it's easy for a reader to tell the card directly on the reader from every other card in the room. No so much for BT. The solution including cellphones we need is NFC, which is basically RFID that can leverage the processing power of the cellphone. It just doesn't exist on very many phones yet.
- moe 16y ago
  Barcodes are 100% copyable and include 0 cryptography That doesn't have to be case, which imho invalidates the rest of your points. It's perfectly doable to issue tamper-proof tickets in the form of cryptographic signatures. So you could, for example, on a website order a barcode that encodes "This ticket valid between 10:00-18:00, on route section X, and belongs to Mr. John Doe". Obviously someone could copy and re-use that very barcode but you have the same problem with RFID tokens, unless there's some sort of centralized validation going on. Which is, btw, actually much easier to implement than you make it out to be, considering you'll have a hard time finding a train-station without GSM coverage nowadays. I do agree with your concerns that not everyone has a phone capable of displaying these codes, yet, but it's a matter of years until that will be the case. During then you'll need the old paper tickets as a fallback - but that's the case with any new technology, it's not like you could flip the switch with RFID over night either. Likewise Bluetooth may indeed be the wrong tool for the job, personally I'd favor the barcodes that seem to work out well enough on airports. And finally, the development effort for making the software work all phone platforms is negligible. Again, the Airlines have demonstrated it can be done, and when you compare it to the effort required to rollout an RFID solution including the hardware then I'd bet the barcode approach is actually easier to do. So. This, for once, is a problem that would be fairly straightforward to solve with technology. I can't help but assume this massive gravity towards more expensive and inferior solutions is mostly a result of lobbying. Obviously there's much more money to be made by handing out physical tokens and then enjoying the benefits of a ridiculously expensive support contract as you pile bandaid over bandaid...
doki_pen 16y ago
This already has happened in Boston. http://joshuamcginnis.com/2008/08/09/wow-how-to-hack-boston-mbta-cards-for-under-15/ http://joshuamcginnis.com/2008/08/09/wow-how-to-hack-boston-... It's really shocking that people think storing MONEY on a card that everyone has read/write access to is a GOOD idea.