They do, but the underlying key must be able to encrypt/decrypt. And I think FROST keys cannot do that.
Discussion
It is not well known, but you can perform a collaborative ECDH with the key shares. I have an example in the @cmdcode/frost library.
Very interesting. Can you do an example with NIP-44? I'd love to get NIP-17 DMs working with FROSTR if possible.
frost2x has NIP-44 integrated. Bifrost nodes construct the shared secret, then pass it into NIP-44 methods (from nostr-tools) for encryption and decryption. NIP-17 should be doable on top of that.
Very cool, then why is nostr:npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6 freaking out that nip44 doesn't work with frost?
honestly I didn't know of an ECDH solution until fairly recently. I stole it from Jesse Posner, full credit to him:
Wow, I didn't know this. Good to learn about this arcane knowledge here.
It is still kinda bad in the multisig bunker case because the coordinator can decrypt your messages, but better than nothing? I'll try to implement it.
That's interesting. How would you combine that with a symmetric cipher?
Once you construct the shared secret, you can plug that into any cipher scheme like normal. Frost2x already handles nip04 and nip44 encryption.
Nice, that's very elegant, great find.
Some time back we used Pallier threshold encryption to basically do Frost for encryption (this was for an online contest use case). That worked in terms of not exposing the encryption key to any single party (keep it cold like Forst) but then we needed a separate Pallier keypair and as far as I remember it could only handle chunks of 100 words or so, depending on the length of the key and byte limit that unlocks, so required stitching up longer texts (or jacking up the key length to get more bytes). I guess that's just a mathematical limit in context of threshold encryption without exposing the full key to any one party.
But not keeping the full encryption key cold here doesn't seem like a dealbreaker to me, and the whole thing is really neat and tidy all bundled in to FROST. You guys are taking some seriously big whacks at this problem. 👍