Apr 25 2010

Oyster “Clamshell” Idea


I shouldn’t be surprised that the cheapest RFID reader is from China. This might be something to get in the next few months. I’m interested to see if I could create an Oyster Card reader to show current balance and if you’re “touched” in or out.

I’m currently imagining something the size of one of those old credit card sized calculators. The little ones that used to run on solar. The best way would probably to package it like the card holders used on ID lanyards, where the card is slipped into the holder. To my mind this would mean the reader coil would be within a millimetre of the cards aerial, meaning it could get away with extremely low-powered use.

While it came to mind, it would probably be impractical to try and top up the reader’s batteries through induction charging when the bundle was swiped through a terminal.

That said though, there is some small encryption used on the Oyster cards. It’s supposed to take less than a second to crack on a laptop, but this tiny reader idea is not a laptop. I suspect though that the card could capture the key when the bundle is first put through a reader. That is, if the key isn’t already universal and/or the portion of data requested isn’t the bit that’s encrypted.

As a general purpose reader it would fail, but as a single-purpose device it’s at least a plausible concept.

I doubt it would get any support from TFL however, since I imagine they make quite a bit of money from people forgetting to touch out (or finding terminals are broken) and having cards charge the daily maximum fee instead.
And I feel a large number of commuters would appreciate an end to waiting half an hour for a bus only to find their card doesn’t have enough credit on it for them to get on board!

Knocked out in China, I think they’d probably sell well for a fiver. Maybe a tenner, but I feel it’d leave space for someone to undercut you then.

Anyone got any actual RFID experience to tell me if the idea’s feasible?

[20/06/2010: Amalgamating old posts from “Dreamwidth Creative Blog” into sci-fi-fox.com to re-purpose DW blog account.]

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