Nostr: What can relays learn about encrypted messages?

Short answer

A relay can see that a client connected, which events it submitted or requested, and some timing and routing information. NIP-17 gift wrapping hides more message details than a simple public-tagged event, but NIP-44 itself notes limits around metadata hiding and forward secrecy. Encryption protects content, not every fact about communication. Use a suitable network connection and client if metadata exposure matters.

Sources

NIP-17: Private messages, NIP-44: Encryption.