I was excited when the ORCA™ smartcard public transit payment system was rolled out. I like the convenience of it -- especially the e-purse (a debit account for transit fare) since, as a full time bike commuter i do rely on the transit system, but i don't take it often enough to make a monthly pass worthwhile. I was an early adopter and use mine frequently. As a transit advocate i got about a dozen of them when they were still free so i could hand them out to my friends.
I like not having to think about carrying exact change and and i like that the transfers are all automatically calculated. (Although i have noticed that the computer is not as friendly with allowing expiring transfers as the drivers were!).
Most of all i really like being able to pay my fare without having to open my wallet. I just wave my wallet in front of the reader. A couple of times i bumped my butt against the reader and it worked, the reader recorded my fare. But the drivers didn't like that very much, they thought i was showing them up. I didn't like that very much either; It really drove home to me that my transit information was broadcasting out the back of my pants all day long.
I'm fascinated with RFID, the method of communication that the smartcards use, i think it's a very interesting technology. As a HAM radio operator i consider my ORCA™ to be just one more cool radio that i use. I like the way it works, converting radio energy into electrical energy and back again; fitting four different electrical devices into a almost microscopic web of electrical wire.
RFID cards have a mesh embedded throughout the entire card which acts as a receiving antenna. When the card reader sends out a radio signal (asking 'Who are you?') that antenna receives the signal. Here's the cool part: the mesh then converts the radio energy from the received signal into electrical energy to power a tiny computer. And the computer? It's the mesh itself! The mesh that makes the antenna is laid out so that it also can work as a microprocessor.
The converted electrical energy runs through the this mesh microprocessor, reading (and writing) data. Then at the end of the run of wires, the electrical energy is converted back into radio energy and the mesh is used as a transmitting antenna to send the data back to the reader.
There is of course loss of energy in all of this, the response signal from the card is much, much weaker than the original query signal from the card reader. This is a benefit, not a problem since it means the card only works if you hold it close to the reader.
One day in March about a year and a half ago, i noticed my mobile phone sitting next to my wallet on the table. I stared at them for a moment and it occurred to me that since the phone was radiating a signal (a pulse at least every 30 seconds alerting nearby cell towers to its presence) that the ORCA™ card in my wallet must be receiving and processing that signal! Although the signal was on a different frequency than the one the card was expecting (1,200 Mhz, not 13.56 Mhz) the signal would still be received and the card must be transmitting its own weak signal, with garbage, not real data.
The next day i was in a Mexican restaurant with a friend telling them about that epiphany. While we were talking i had an idea. I took the foil that had wrapped my burrito and wrapped a piece around a business card. I stuck it in my wallet, outside of my ORCA™ card, but next to it, touching the card. Aluminum foil can act as a weak faraday cage -- that is it can stop or at least scramble up radio signals. My hope was that i could still wave the inside of my wallet (the part usually against my body) over the reader, but the outside would be blocked. The foil doesn't have to stop the stronger incoming signal from the reader, it only has to stop the very weak outgoing signal response from the card.
A few days later i tried it on the bus. The reader would not read my card at all. Neither the front or the back of my wallet would work. I had to remove the card. Frustrating, but still, an interesting result! The foil touching the card disabled it. That could be beneficial.
So after i sat down on the bus i moved the card in my wallet. I moved it so that instead of actually touching the ORCA™ card, the foil was about 5 credit cards away from it -- still outside of it. On the connecting bus i tried waving the outside of the wallet over the reader -- it would not read. The driver was waiting for me, so i hurriedly flipped my wallet over and waved it and it did read from the inner side of the wallet!
Excellent! This works. If these results held true, i had something that could either:
- block RFID transmission from the outside of the wallet (while my body blocked the inside.) or
- entirely disable a RFID while in the wallet.
This would be useful!
I liked the idea of using it, but it also seemed like an opportunity. I figured i could make them pretty easily. I came up with the name "The ORCA Fin" and designed some business card sized labels. I printed out the labels, cut some thin foil to the same size and took it to Kinkos and laminated it. I now had a credit card size shield with a label and logo. I made two of them -- a prototype with 1 sheet of thin foil plus one sheet of paper (with the info) and, just to be sure, another prototype with 2 sheets of foil in addition to the info card.
On March 31st i checked the web and theorcafin.com was taken, but orcasfin.com was not; i bought the domain orcasfin.com. I created a ORCA's FIN site on my webserver and put a placeholder webpage up.
I figure with PayPal and a simple form system i could take orders, charging $5 each, i pay domestic shipping. I need to price printing, lamination and postage. I think postage will be 80 cents, but that will depend on the final design. The labels, 16 per page, are just a couple of cents. I might buy a lamination machine rather than using Kinkos at $1.25 each time. Then i need to re-write the instructions on the logo labels. I'll need to write a little script on my website to run the order form. I'm inclined to go paypal only, but maybe find a way to take credit cards. Then i need to start talking about them, handing them out. Send one to the Electronic Freedom foundation, maybe one to Boing Boing. And then buy foil and start making them.
ORCA™ uses the MIFARE™ system. A number of other transit systems around the world use this system and there are at least 3 other systems that use 13.56 Mhz credit card systems for fare paying or access (such as Zipcar). And if this works for MIFARE™ it should work for all of them. It occurred to me that i will need to think of a different name if i'm going to sell them outside of Seattle. I like the word play of ORCA's Fin. I want a word that implies blocking. I need to work on that: Smartcard shield?, tinfoil hat?, card condom?, fare protector?, card cage?, wallet wall? So far i think Wallet Wall is best.
So once i tested the laminated version, i was ready to go. The next time i took the train i tested it. It failed! Neither prototype was able to block the signal at all!!! Not touching, not spaced, not outside or inside. I was a bit disappointed. I tried again in mid April, the next time i took the train, with the same disappointing results. But this time i discovered that i can wave the card over the reader a second time to cancel my fare -- meaning that i don't have to ride the train to test the cards, i just have to go to the station. Since i only ride the train once or twice a month and the bus less often, this was a very good discovery.
So i made two more prototypes using much thicker foil. These were prototypes #3 & #4. (If you count the raw foil one without lamination as #0.) One had one layer of the thicker foil, the other had two layers. These also each had two paper labels, one on each side, completely hiding the foil and giving me more room for instructions. They looked pretty good. I tested these prototypes repeatedly in mid April. No luck. I didn't test them touching the smartcard -- maybe i should have.
Next i laminated two more prototypes -- the sixth and seventh prototypes, marked them #5 & #6 (still counting the non-laminated one as zero). Prototype #5 has three layers of much thicker foil. Prototype #6 has SIX layers of much thicker foil. In July i took them down to the light rail station to test them. Neither seemed to work at all.
This was frustrating, i put the whole thing aside for a while, but i may pull it out and work on it again. I'm pretty disappointed at this juncture. I'm not sure why they are not working, some ideas i've had:
- Perhaps the shield is not quite as wide as the smartcard by a few millimeters on all four edges and maybe that's just enough for the outgoing signal to leak around. That seems pretty unlikely to me.
- Perhaps the foil is still just not thick enough. But the thin foil works without lamination.
- It doesn't make any sense, but maybe the lamination is preventing the foil from shielding. I'm pretty certain the lamination is going to prevent the foil from completely disabling the card, i think it needs actual contact with metal for that to work.
- Maybe the first test didn't actually work and just foil isn't going to stop the signal at all.
- or maybe there is something obvious that i am missing.
I kept the ORCA's Fin in my wallet, in the outside location that i wish worked throughout the autumn. Occasionally when i rode the bus i'd give it a try, but it never blocked anything. In early December i walked downtown and duplicated the original test.
- My prototype #6 (laminated with 6 layers of foil and 2 of paper) has been living in my wallet for months, outside of my ORCA™ card, spaced. I tried it. It failed to stop the signal in any way. Damn.
- I put the foil only prototype #0 (2 sheets of thin foil wrapped around a business card) in my wallet spaced away from the ORCA™ card. It worked!! It stopped the card from working on that side of the wallet, it still worked from the other side.
- I moved the foil prototype to touching the ORCA™ card. It disabled the card entirely. Success!
- I tried a new thing -- i put the foil in, spaced away from the ORCA™ card and put the laminated (#6 with 6 layers of foil) Fin outside of it (so my visa card will slide in and out freely). That worked. I'm going to leave it that way, that will be my basic wallet configuration.
Next time i will try with the laminated Fin inside of the foil prototype. Perhaps that will show me something about the lamination. I can't understand why the raw foil prototype works and the laminated ones don't. I can't see how lamination could nullify a faraday effect, besides there are several laminated cards between the ORCA and the foil in the working system. I don't think the foil is really any wider than the foil in the lamination. I don't get it.
It doesn't look like i can sell them, but at least i get the functionality!!
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