5 ms·

Things a cheap calculator needs to do: - Simple arithmetic on an occasional basis Things a NFC card implementing the system you describe: - Radio - Public k

Things a cheap calculator needs to do: - Simple arithmetic on an occasional basis Things a NFC card implementing the system you describe: - Radio - Public key crypto - ASN.1 DER X.509 parsing to validate the signed transaction from the terminal. The terminal would need to send a cert chain to the card and the card follow the chain to the network root to correctly verify the terminal signature. - Parsing OCSP responses, which the terminal would have to staple to its cert because the card has no other way of knowing the revocation status of the terminal cert. - Conform to ISO 7816 for interoperability with legacy equipment. - Fit in a wallet/purse/pocket - Be a reasonable cost

honkhonkpants 10y ago
I already have a cryptocard that does all that junk just from the RF power it gets off the terminal.
- sjtgraham 10y ago
  I bet it's not interactive. Interactivity powered by near field RF is impractical because power is lost when the card is out of range. This would result in some very awkward UX as users have to hold their card close enough to the reader for power while they verify the transaction metadata and enter their PIN.
  - viraptor 10y ago
    Check with people who already use this: https://newsroom.mastercard.com/press-releases/mastercard-introduces-next-generation-display-card-technology-a-first-for-singapore/ https://newsroom.mastercard.com/press-releases/mastercard-in... Producer: https://www.nidsecurity.com/products/solution-financial.html https://www.nidsecurity.com/products/solution-financial.html
viraptor 10y ago
This is a standard for smartcards. They often include certificate-based authentication. You don't power the radio - the radio powers you, so that's not a big issue. OCSP seems irrelevant - it's pass-by-default, so if you're a bad guy you just pretend you can't reach the OCSP servers.
Retric 10y ago
You can do that for under 20 cents in bulk with a power budget of around 0.01 watts. Modern CPU are kind of mind bending awesome, but you can also get useful processing at the 35µA level.

honkhonkpants 10y ago

I already have a cryptocard that does all that junk just from the RF power it gets off the terminal.

sjtgraham 10y ago
I bet it's not interactive. Interactivity powered by near field RF is impractical because power is lost when the card is out of range. This would result in some very awkward UX as users have to hold their card close enough to the reader for power while they verify the transaction metadata and enter their PIN.
- viraptor 10y ago
  Check with people who already use this: https://newsroom.mastercard.com/press-releases/mastercard-introduces-next-generation-display-card-technology-a-first-for-singapore/ https://newsroom.mastercard.com/press-releases/mastercard-in... Producer: https://www.nidsecurity.com/products/solution-financial.html https://www.nidsecurity.com/products/solution-financial.html

viraptor 10y ago

This is a standard for smartcards. They often include certificate-based authentication. You don't power the radio - the radio powers you, so that's not a big issue. OCSP seems irrelevant - it's pass-by-default, so if you're a bad guy you just pretend you can't reach the OCSP servers.

Retric 10y ago

You can do that for under 20 cents in bulk with a power budget of around 0.01 watts. Modern CPU are kind of mind bending awesome, but you can also get useful processing at the 35µA level.