3 ms·

NFC transactions are powered by the EMV chip, and include all the same signing ond one-time-key exchange as a chip-insertion but without the potential for skimm

NFC transactions are powered by the EMV chip, and include all the same signing ond one-time-key exchange as a chip-insertion but without the potential for skimming the mag strip

tjoff 4y ago
Encrypted in the same sense that https is encrypted. Doesn't do jack if you have control over the "server". And in this case the server can have a large antenna and not require physical contact. So in essence, orders of magnitude worse than the magnetic strip.
- aerostable_slug 4y ago
  This is fundamentally incorrect. Sniffing the NFC traffic gives the attacker nothing useful, just as skimming an EMV contact transaction gives the attacker nothing useful. >The contactless EMV chip transaction path leverages the cryptographic functions normally associated with a contact EMV chip transaction and uses the same authorization and settlement fields as a contact chip transaction. [0] [1] [0]: https://www.emv-connection.com/downloads/2015/12/EMV-and-NFC-WP-Final-Nov-2015.pdf https://www.emv-connection.com/downloads/2015/12/EMV-and-NFC... [1]: See EMV specifications, “Book 2 – Security and Key Management,” Version 4.3, November, 2011, http://www.emvco.com/specifications.aspx?id=223 http://www.emvco.com/specifications.aspx?id=223.
  - tjoff 4y ago
    Why would you need to sniff anything? Just ask for it yourself. That's what I meant with encryption not meaning jack if you are one of the participants.
- notatoad 4y ago
  the "server" in this case provides a one-time key to sign the transaction with, which is only valid for that transaction and that merchant. if you have a large antenna that can provide valid transaction keys for a trusted merchant, then yes, you have a significant exploit. to my knowledge, nobody has ever successfully demonstrated an exploit of this nature.
  - tjoff 4y ago
    The "server" in this case is a rouge device. It is trivially employed.
    - notatoad 4y ago
      I’m not sure why the color of the device matters here

NFC transactions are powered by the EMV chip, and include all the same signing ond one-time-key exchange as a chip-insertion but without the potential for skimming the mag strip

tjoff 4y ago

Encrypted in the same sense that https is encrypted. Doesn't do jack if you have control over the "server". And in this case the server can have a large antenna and not require physical contact. So in essence, orders of magnitude worse than the magnetic strip.

aerostable_slug 4y ago
This is fundamentally incorrect. Sniffing the NFC traffic gives the attacker nothing useful, just as skimming an EMV contact transaction gives the attacker nothing useful. >The contactless EMV chip transaction path leverages the cryptographic functions normally associated with a contact EMV chip transaction and uses the same authorization and settlement fields as a contact chip transaction. [0] [1] [0]: https://www.emv-connection.com/downloads/2015/12/EMV-and-NFC-WP-Final-Nov-2015.pdf https://www.emv-connection.com/downloads/2015/12/EMV-and-NFC... [1]: See EMV specifications, “Book 2 – Security and Key Management,” Version 4.3, November, 2011, http://www.emvco.com/specifications.aspx?id=223 http://www.emvco.com/specifications.aspx?id=223.
- tjoff 4y ago
  Why would you need to sniff anything? Just ask for it yourself. That's what I meant with encryption not meaning jack if you are one of the participants.
notatoad 4y ago
the "server" in this case provides a one-time key to sign the transaction with, which is only valid for that transaction and that merchant. if you have a large antenna that can provide valid transaction keys for a trusted merchant, then yes, you have a significant exploit. to my knowledge, nobody has ever successfully demonstrated an exploit of this nature.
- tjoff 4y ago
  The "server" in this case is a rouge device. It is trivially employed.
  - notatoad 4y ago
    I’m not sure why the color of the device matters here