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by compsciphd 3282 days ago
AFAIK (please correct me if I'm wrong) NFC is more akin to magnetic strip than chip cards are. i.e. a virtual number is created for each transaction that is tied to the merchant / time of use. so, you get an id from the merchant (i.e. direct communication between you and reader) you get a virtual number from you credit card provider (1 internet trip), and you give that virtual number to the reader), then phone is back in pocket while it does its thing.

Samsung pay even cuts out any knowledge of the reader, just gives a virtual number to the credit card mag reader.
2 comments
dfox 3282 days ago
NFC uses the same protocol and transaction flows as contact chip EMV. Only designed-in difference with regards to speed of processing is that card contains additional application that returns AID that should be used instead of terminal trying AIDs it knows blindly. Another thing is configuration. NFC typically has many "slow" transaction flows disabled (ie. anything that requires the card to be still present after some other interaction, be it pin entry or reply from payment processor).
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PeterisP 3282 days ago
If we're talking about contactless EMV cards (Phone NFC may be otherwise), then they do pretty much the same thing crypto-wise as in a contact transaction, the chip receives the transaction from the terminal.

The main practical difference is that you can't update the on-card data depending on the transaction outcome, since the card isn't there any more.

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