Passive e-ink display on JCOP4 cards

[praveenbm5]

I am a complete noob when it comes to Javacards and Smart Cards. So please bear with my ignorance.

I was wondering if JCOP4 cards can be made to include an e-ink display (passively powered by NFC power harvesting) that will be used to show some infomration regarding the operation being performed on the Javacard.

For instance, lets say we are using the Javacard to sign a payload from the master device using an ECC prevate key stored in the SE.

Currently, the master device relays the payload over NFC to the javacard which then signs the string and relays the signature back to the master device.

This has one important drawback that we cannot confirm what the javacard is actually signing and we have to trust the master device to only sign what it says it is signing on its interface.

Now lets assume the javacard has an e-ink display that can show some information about the payload and signature generated as a QR code.

At the very least, we know what it is signing and if the master device has a camera, we can then break this operation into a two step process.

1. Javacard receives the payload from master device and generates the signature as usual but does not relay the signature back to the master device over NFC. Instead it displays the payload or hash of it and a QR code containing the signature on the inbuilt e-ink display

2. We check the payload (or its hash) and then scan the QR code containing the signature shown on javacard e-ink display using the master device camera only if everything looks OK.

[msjcard]

Previous version of the JCOP series have one or two GPIO pins on various packages (e.g. QFN20).  Which implies a "yes" with a bunch of work.  You may want to have a talk with your sales rep or engineer under NDA for a deeper dive, but I don't think that would be a worthless talk.

[praveenbm5]

How can P71D320 chip send data to MCU for displaying the data on eINK display? is UART, I2C or SPI avilable on P71 to communicate with other ICs?

I am hoping to build something on these lines. Or may be we can use separate coils for P71 and MCU where the MCU will use the NFC coil only to harvest energy

[praveenbm5]

Hello Kan

Thank you for the quick response. Any pointers as to how we can integrate LPC8N04 together with an e-Ink display into a javacard?

[Kan_Li]

Hi @praveenbm5 ,

Actually I don't think the JCOP4 card supports NFC power harvesting to power the e-ink display as well as itself, maybe you have to use a MCU like LPC8N04 with them as well?

Have a great day,
Kan

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