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The chip on the card is an entire computer running a Java program every time it's activated by the terminal. What it communicates via that terminal can vary, th
by ztjio 8y ago
The chip on the card is an entire computer running a Java program every time it's activated by the terminal. What it communicates via that terminal can vary, the same way the NFC tap-to-pay terminals can vary. There's no need for it to carry a conventional card number or expiration or anything.
- jdillaaa 8y agoWhy on earth would it run java?
- parisidau 8y agoThe secure element on iOS devices is a Java Card (https://www.apple.com/business/site/docs/iOS_Security_Guide.pdf https://www.apple.com/business/site/docs/iOS_Security_Guide.... p. 47).
- favorited 8y agoBasically all smart cards use Java Card. There's an ISO standard, so I'm sure it's possible to implement your card in other environments, but everyone uses Java Card.
- sebazzz 8y agoIt is nothing like the real Java. Almost no regular data type is supported and there are severe limitations. [1] You should view it as using a safe language instead of something like C. If Rust had been invented 20 years ago, it might have been Rust instead. [1] https://en.wikipedia.org/wiki/Java_Card https://en.wikipedia.org/wiki/Java_Card
- jdillaaa 8y agofascinating. thanks!
- kalleboo 8y agoBecause these practices were set in the mid-to-late-90's when it was fashionable to Java all the things
- kevindong 8y agoMy reasoning operates under the assumption that the chip that communicates with the payment terminal sends a card number to the terminal at some point in time. I do not know how the protocol works in reality however.
- cptskippy 8y agoThat might be a fallback option but modern terminals do not need a card number.