Regarding metadata privacy protection, we find the NIP-59 approach unintuitive and the idea complex. We believe that the key to protecting metadata privacy is to separate the sending and receiving addresses from the ID and to continually update these addresses. Just like the Signal protocol separates the encryption keys from the ID and updates them regularly to achieve better message encryption.
“The current Nostr DM (NIP4) integrates four capabilities into a single Nostr key—it serves as an ID, an encryption key, a receiving address, and a sending address.
In Keychat, the ID, encryption key, receiving address, sending address are separated, allowing the encryption key , the receiving and sending addresses to be updated continually. This achieves better encryption security (forward secrecy and backward secrecy) and metadata privacy.”