For some Nostr applications, it is important to have data that can be verified, but that you don't want to be published (eg SIGit agreements, medical records, or internal application data).  One way to achieve this is by sealing (kind 13) but this has some drawbacks - such as the fact that only the sender and receiver can decrypt / verify the content.

NIP-59 suggests that removing the signature is one way to prevent events from being published.  But this also stops it from being verified.

With this in mind, we would like to #asknostr for feedback on the following idea.

Using negative kind numbers for private data

Negative kind numbers MUST NOT be published to relays, and relays MUST NOT accept negative kind numbers

Thoughts?