Nostr suggestion.

2 layers of security:

Full-key (24 or 48 words)

Half-key (12 or 24 words)

Half-key would mean the first half of the words of the full-key.

At half-key level of security we can sign messages and do most things we can now.

At full-key level of security we can flag our profile as compromised, as well as deleting all half-key-signed notes after a date yy-mm-dd.

I guess we could also allow the deletion of all our notes at the full-key level.

Usage: the regular user would normallt use the half-key to access their Nostr profile and sign notes.

When/if the half-key is hacked/stolen, the user can flag their profile as compromised and set all new half-key-signed notes to be deleted. The user can now post messages with their full-key and explain what happened, create a new Nostr profile and guide their friends there.

The thief with half-key access would have their half-key-signed notes deleted due to the compromisation flag.