That's what the signer is, a small bunker device you run yourself and is dumb microcontroller to limit the attack vector

The ESP32 used by these signers is not a very secure chip. Most MCUs in general including STM32, ESP32, RP2350 etc lack security features. While most devices use secure elements, they export the key to the insecure MCU once the boot is complete. This requires an on-SE signing solution. I am currently building the first secure element designed for Nostr and Bitcoin, ensuring your keys never leave the device. This is based on an EAL6+ chip from a large SE vendor that also protects billions of credit cards and passports. There are 2 distinct possible use cases: - A USB stick you can plug into a home server like an Umbrel or a Start9, that provides a secure storage for your keys and a trusted anchor for future use cases, and can allow most actions without review. - The HWW device I am working on will be able to store and handle Nostr key operations with manual approval for the more sensitive event kinds. This also uses a security-hardened MCU.

Maybe one can simply extend SpecterDIY to handle Nostr keys. With the keys stored on a SmartCard this should be rather secure.

Any chance your work could also include VLS support too?

> they export the key to the insecure MCU once the boot is complete Why would they do that? An SE can sign on-chip which is its very purpose. Can you point me to the code in any open source firmware implementation where that happens? I don't even believe SEs have functionality to export persistent keys.

> This is based on an EAL6+ chip from a large SE vendor that also protects billions of credit cards and passports. You mentioned the NXP SE050 before which is marketed as an IoT chip ... Nitrokey uses the NXP P5DF081 which is more geared towards smart card use but otherwise not much different.

It's probably secure *enough*. It's one of those perfect is the enemy of good things. I hear that the TROPIC02 chip will have on chip secp256k1 signing. Big deal.

But, yes, I largely agree.

Tropic reminds me of

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