Cards use a contactless smart card (MIFARE) system, and multiple trips may be purchased for one card.
MIFARE |
At the 27th annual German Chaos Communication Congress hacker conference ("27C3") in 2010, German free software programmer Harald Welte showed that it is possible to artificially change the amount of money stored on a first-generation EasyCard—based on the MIFARE Classic—using nothing more than a USB RFID reader and a laptop computer running open source software.