Over the pandemic I got a new job that will in theory eventually require commuting downtown to an office… in theory. Transit here has an RFID fare card system, and if I am taking transit downtown and back every day, I’m thinking I may want an implant or conversion.
I know it uses a DESFire EV-1, and found Inside Compass Tickets which has a ton of info, but I don’t understand enough of it to know if it’s something that can be made to work with an XDF2 or other existing implant.
I assume I’d need a conversion. In which case, they offer a hard “credit card” style card, a silicone wristband, and a keyfob in hard plastic… presumably of the three, the wristband would be the easiest to work with?
Interestingly enough, their website says the wristband and keyfob can only be purchased at certain locations because “we have to encode them with a special machine” so maayybbee an implant can be registered??
They might just be registering that specific wearable in their system. I did notice that registering a machine purchased card requires a 3 digit code that is printed on the card but for a wearable they will provide it separately.
They may just think that there will be less call for wearables than cards and so the cards can be auto vended (and record the machine number that vended that card on them) but the wearables don’t have the same infrastructure available for them.
A card is dissolvable in petroleum products according to the site you linked, so if @amal has a suitable antenna already he should be able to do a conversion of that quite readily. I am not sure it would be as easy to extract a wearable from a silicone wristband.
Before you get a conversion (assuming your transit card is a good candidate), I suggest you do a few experiments to find out whether it’ll work at all.
I tried my very best to evaluate whether mine would, by getting traces of the transactions between my card and the readers in my local busses with my PM3, tried a few range experiments, decided to get my bus card converted despite the worryingly short range with the full-size card, and in the end the conversion didn’t work (you can read all about it here).
My advice is: unless your transit card rings REALLY easily on the readers, at least half an inch from the surface, don’t bother.
I would try to convert the band myself, because the antenna in it is the smallest of the 3 - meaning at least you know that one performs well with an antenna approaching the size of the DT copper antenna, should you decide to convert it.
The trick is to extract the chip (or mini-card) from the band without ruining it.
IF it is like the one I dissected, I found that part very easy, but the reason I put it on the bottom of MY list, was, mine was potted, and I was unable to separate the antenna and chip from the enclosure. and as is, it would likely be too thick for encapsulation
I’d go card first then fob… and from the look of the card with the light through it’s probably a COB. What type of chip does taginfo say? Is it confirmed to be a desfire? Does taginfo tell you if it’s the 70pF version of 17pF?