Delete can't be real because someone will always have their phone out there ready to screenshot your post.
Imagine the @ protocol was
```<ed25519 Public Key><Signature>```
and that opened to
``` <timestamp><ed25519 Public Key><Previous Post Hash><Data Hash> ```
And the previous post hash could point to a post before a delete if we consider deletes to be real.
The hashes are used to lookup the post content, which we could also send with the message for the sake of convenience.
For key rotation we just need to sign a message pointing to our new keypair, no federated servers required! "My new key is EVxe89AeRwmTT0hfrT7sHe0wAuzvH9Yvg9TFUgqPh4M="