Wonder if we could use OpenTimestamps and on-chain keys as a second factor for Nostr authentication. For example you could sign a message attesting to your ownership of an npub with a key to one of your UTXOs and stamp it and then publish it on Nostr in your profile.

Use case: suppose your nsec becomes compromised and you want to inform your web of trust to swap out your npub for a new one. We need an independent and decentralized way to differentiate the correct npub from an attacker’s.

Seems better than NIP-05 which is DNS based.