Discussion was about cipher block modes in the context of Nostr and NIP-04. You might notice all 3 levels above your comment reference either the Nostr protocol in general, or NIP-04 messages.

> And GCM does not ‘add’ a signature per se.

Your own comment to which I replied said "It’s not tamper proof, ie signed, unlike GCM". Wouldn't most people consider something "signed" as having a signature?