Show HN: Qryptr – airgapped ecc text messenger

Dear HN,

I am excited to share my work which I published on Github recently as an open source project and is now ready for you to review/try out.

It is a small, physical device with a keyboard, screen, camera and microcontroller (RP2040).

With this device you can read and write text messages of up to 299 characters which are ECC encrypted and then displayed as QR codes. The QR codes can be photographed/shared with your smartphone.

Importantly, this device has no network connections at all and runs on a microcontroller, to minimize the platform complexity.

The point of the device is to do encryption/decryption on a device physicially seperated from your smartphone. In this way, even if your smartphone is compromised, you can still send messages securely.

I have reviewed quite some security measures such as yubi keys, hsms and cryptographic coprocessors, but I figured out I wanted to still proceed with this project. For fun, and perhaps it can be useful for someone. I certainly had a lot of fun building it.

I decided against a kickstarter because having people pay me comes with a lot of responsibilities. So you have to build it yourself. Of course I can help you and I am available in the comments for questions.

Please let me know what you think about it.

Regards,

Thomas.