Nostr: Are Nostr direct messages private?

Short answer

Privacy depends on the messaging scheme and client. NIP-17 defines encrypted messages using NIP-44 and gift wrapping, while older schemes have different protections. Encryption protects message content from relays that cannot decrypt it, but it does not erase all metadata or protect a compromised device or key. Check which scheme both participants' clients support before sharing sensitive information.

Sources

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