Replying to Avatar BlackCoffee

The ESP32s are really neat and there's definitely some hardening that can be done with the secure boot, signed firmware features.

Key delegation with an expiry time would be really nice! Good idea.

I don't have any SE experience on ESP32s but from the research I've been doing, you're right, the ATECC608B can't do schnorr sigs. The Coldcard uses this SE and it is compatible with taproot so I'm wondering if there's a way of working this. Either that or CK are using the DS28C36BQ. I need to research more.
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frphank 1y ago

The DS28C36 is NIST P256 too? https://www.analog.com/media/en/technical-documentation/data-sheets/ds28c36.pdf

(This link above btw is an abridged data sheet. The full datasheet is under NDA for which I call bullshit. Friends don't let friends use Maxim.)

The Koblitz curve is really exotic outside the blockchain/nostr bubble. Nostr doesn't use Schnorr sigs AFAIK just plain EcDsa.

Not sure how Coldcard works.

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BlackCoffee 1y ago

I'll have a look at the data sheet. Thank you. I'm very new to using SE so it's going to take some figuring out.

Here's the schnorr sigs nostr stuff

https://github.com/nostr-protocol/nips/blob/master/01.md#events-and-signatures

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frphank 1y ago

Schnorr sigs indeed not sure where I had the idea about EcDsa from. That's even more exotic then. The NXP SE050 would to Koblitz curves in some configurations but just EcDsa not Schnorr. Good luck finding an SE that can do that.