NUT-xx: mint list backups on nostr for wallets

[callebtc]

Spec for backing up a wallet's mint list on nostr as a replaceable event.

Implementations:

• cashu.me
• Numo PoS
• cdk feat: nostr mint backup cdk#1459

[Kelbie]

This looks good, thoughts on having a way to blacklist keysets or some other way to skip going through keysets which we know don't have any unspent proofs? I notice with cashu .me if you try to restore on testnut mint with rotating keysets it rate limits you.

This might not be a problem in practice with real mints. I figured I'd mention it anyway.

[callebtc]

This looks good, thoughts on having a way to blacklist keysets or some other way to skip going through keysets which we know don't have any unspent proofs? I notice with cashu .me if you try to restore on testnut mint with rotating keysets it rate limits you.

This might not be a problem in practice with real mints. I figured I'd mention it anyway.

iiuc, question about the restore strategy doesn't seem to be related to this PR. you could store much more wallet state on nostr like the keysets used etc (but that's out of scope for here).

[Kelbie]

You are right, it is a bit out of scope for this PR. Everything else looks good! 💯

[thesimplekid]

I pushed a commit 897a291 with a test vector for the key derivation. Feel free to revert it if its wrong or unneeded.

implemented in cdk PR: cashubtc/cdk#1459