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Rod 1y ago

I think I just worked out a new signing workflow.

We can approximate an offline signer using an NFC card that holds an nsec.

Design a nsecbunker, and delegate signing to the bunker, but populate the bunker with a transient nsec, similar to Amethyst transient login.

Client asks bunker for signature. Bunker requests NFC tap in order to get the nsec. On tap, bunker applies the password, signs the event, and then forgets the nsec.

Required to trust the bunker software, but if the bunker gets hacked, or device gets compromised, it does not possess the key.

Thoughts?

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semisol 1y ago

You know, you could move the entire signing process onto the card, and I am doing that

You are forgetting that the average user can need to sign up to 5 events/sec. AUTH, media uploads, etc

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Rod 1y ago

I'm not forgetting, I'm just ignorant!

Backlog and batch sign?

Doing signing on the card was the first place I looked. I found secp256k1 seemed poorly supported on yubi and other platforms. Maybe wrong.

Also, NFC cards are very cheap.

Thinking of ways to get 100's and 1,000's of users onboarded cheaply without them being able to stuff up and leak their keys.

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semisol 1y ago

Smartcards are also cheap

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semisol 1y ago

Also, batch signing does not make much sense.

You need to send the AUTH event immediately for example

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BlackCoffee 1y ago

Are you using javacards? I've actually implemented something similar to Rod's proposal with the ntag424 DNA (the same NFC chip as in a bolt card) and a remote signer. Works well.

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semisol 1y ago

None of them