|
My OysterCard Whinge
On Sun, Jul 13, 2008 at 05:10:34AM -0700, John B wrote:
...which, by then, they'd realised was the case. I'm not sure what the "code 30" issue is, but it does mean that an unspecified number of unfortunate types like yourself need a new physical Oyster card. But the best thing is that those can only be issued at tube stations, which sucks if you live in Croydon and only use Oyster for local buses. Such people have to either say bye-bye to whatever credit was left on their now broken card, or make a special journey, paying the cash penalty fare, to a tube station (see the fifth paragraph he http://www.tfl.gov.uk/tfl/news/oyster.aspx). More proof, not that we needed it, that Oyster was never thought out properly and that people living in south London don't matter to TfL's management. A well-designed system fails gracefully. Oyster doesn't. I'm not sure what the legal rather than practical situation is, but I'd be amazed if it were different - LUL staff aren't really trained in the mysterious vagaries of National Rail, and don't tend to have a clue about Gold Cards, Network Cards, etc. Perhaps they should be, if they're going to try to do stuff with National Rail tickets. And vice versa, of course. -- David Cantrell | Enforcer, South London Linguistic Massive Perl: the only language that makes Welsh look acceptable |
My OysterCard Whinge
On 14 Jul, 11:46, wrote:
On Jul 14, 11:22 am, Roland Perry wrote: If the mechanism for permanently disabling a card means they have to be touched to a gate that would rather follow wouldn't it? So you think the idea was to disable *some* cards, but the system had a brainstorm and disabled *all* of them? That would be my guess - a simple programming mistake caused some isThisADodgyCard() test always to return true so it killed them all. I don't know if you can update the firmware in the cards. Do they even have something to update? Some simple cards are hardwired with just a couple of numeric registers to carry values but Oysters will have onboard software because they have to store a simple database of places and times visited plus there's encryption going on. Whether that software is in ROM or something read-write akin to flash that can be updated I dunno. Obviously it has some sort of R/W memory to store the DB , balance etc anyway. This is more consistent with their inability to "reverse" the process. It's more scalable to do it that way than to have a blacklist of cards available at every single Oyster reader. Yup. I have a feeling we haven't heard the end of this. Certainly not from the poor buggers who got stranded with a broken card either. :o) I am not a techy, and I was thinking at first that surely there is something that can be reset rather than having to replace the card. But I wonder if it's something like the way that (the surely soon to be extinct because useless) CDs and DVDs become useless if a write operation fails. Like some sector that tells the reader where to look next is corrupt, rather than just a readable setting that says the card is invalid. |
My OysterCard Whinge
On 14 Jul, 18:42, Tom Anderson wrote:
That article isn't outrageously detailed or specific, but taking it together with the generic article on smart cards, i'd say that Oyster is basically just memory, with a chip for accessing it and doing some encryption. I would imagine it doesn't have firmware, BICBW. Where do you think the encryption algorithm and the communication protocol are stored? They're called "smart" because they have a microprocessor running software that decodes commands and reads, encrypts and transmits the requested data. (Although whether this software is rewritable over the air is another matter) U -- http://londonconnections.blogspot.com/ A blog about transport projects in London |
My OysterCard Whinge
On Mon, 14 Jul 2008 18:42:25 +0100, Tom Anderson
wrote: That article isn't outrageously detailed or specific, but taking it together with the generic article on smart cards, i'd say that Oyster is basically just memory, with a chip for accessing it and doing some encryption. I would imagine it doesn't have firmware, BICBW. So, a lot more basic than, say, Chip & PIN, which uses a Java-based (I think) card that is actually a computer in its own right, thus giving a far higher level of security than a card with just a PIN number stored in memory on it. (You can't, for instance, retrieve the PIN from a C&P card, only ask it if the PIN you give is correct, and you can only do that 3 times before it locks). If true, that is genuinely surprising. Neil -- Neil Williams Put my first name before the at to reply. |
My OysterCard Whinge
On Mon, 14 Jul 2008, Mr Thant wrote:
On 14 Jul, 18:42, Tom Anderson wrote: That article isn't outrageously detailed or specific, but taking it together with the generic article on smart cards, i'd say that Oyster is basically just memory, with a chip for accessing it and doing some encryption. I would imagine it doesn't have firmware, BICBW. Where do you think the encryption algorithm and the communication protocol are stored? In a ROM. To my mind, it has to be modifiable to be firmware, which makes code in a ROM not firmware. Although thinking about it, my mind is probably wrong on this point. Or it could be done with an ASIC that isn't a microprocessor. It doesn't need to be any more than a memory controller with an encryption processor glued on the side. They're called "smart" because they have a microprocessor running software that decodes commands and reads, encrypts and transmits the requested data. Microprocessor or ASIC? tom -- Get my pies out of the oven! |
My OysterCard Whinge
On 14 Jul, 23:14, Tom Anderson wrote:
They're called "smart" because they have a microprocessor running software that decodes commands and reads, encrypts and transmits the requested data. Microprocessor or ASIC? To be pedantic, the MIFARE chip is undeniably an ASIC, because that simply means the chip it's custom designed. I think what you're asking is whether the protocol and encryption algorithms are implemented in hardware (using state machine principals) or MPU+software. It looks like encryption and some of the communication protocol is indeed implemented using state machines, but I'm not certain about the higher level functionality, though I'm leaning towards state machine also. Some of the later models are definitely microprocessor-based, though. (although being really pedantic, a microprocessor is just a fancy state machine) U -- http://londonconnections.blogspot.com/ A blog about transport projects in London |
My OysterCard Whinge
In message , at
23:14:56 on Mon, 14 Jul 2008, Tom Anderson remarked: To my mind, it has to be modifiable to be firmware, which makes code in a ROM not firmware. Although thinking about it, my mind is probably wrong on this point. Lots of people these days take the precaution of making firmware upgradeable, but that's not part of the definition - which is non-volatile software providing the lower levels of API (not the user interface) to a dedicated bit of hardware. -- Roland Perry |
My OysterCard Whinge
On Jul 14, 11:14 pm, Tom Anderson wrote:
In a ROM. To my mind, it has to be modifiable to be firmware, which makes code in a ROM not firmware. Although thinking about it, my mind is probably wrong on this point. Firmware is any built in software that controls the low level functionality of a piece of hardware. Doesn't matter how its stored. Or it could be done with an ASIC that isn't a microprocessor. It doesn't need to be any more than a memory controller with an encryption processor glued on the side. So what do you think will be running the encryption processor? I don't know what a circuit hardwired to do something like 3DES or Blowfish or whatever encryption Oyster uses would look like, but I suspect it would be a nightmare to design and debug if it were even possible. They're called "smart" because they have a microprocessor running software that decodes commands and reads, encrypts and transmits the requested data. Microprocessor or ASIC? Most ASICs these days have embedded CPUs. B2003 |
My OysterCard Whinge
|
| All times are GMT. The time now is 03:28 AM. |
Powered by vBulletin®
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2006 LondonBanter.co.uk