Ever wondered how private chats work on a public, decentralized network? This deep‑dive explains Nostr Kind‑4 (NIP‑04) encrypted direct messages – from the ECDH shared secret to AES‑256‑CBC encryption – and reveals what’s truly private (content) vs. what’s still public (metadata). Learn how your messages stay safe without a central server ever touching them.
NIP-17 promises deniable messaging with its three-layer design: an unsigned "rumor," a signed "seal," and an ephemeral "gift wrap." However, this setup has a hidden vulnerability. The signed seal allows recipients to prove that a message was sent by the claimed author, even without revealing the content. This creates a perfect scenario for gossip attacks, where the mere proof of communication can damage reputations. As we explore NIP-17, we find that the rumor, despite being unsigned, is not as deniable as it seems, making it a potential risk for exposure.
Today I want to write down some thoughts on what it really means to have private communications over public infrastructure, and whether such a thing is even possible at all.
