NIP-70 defines a way for authors to mark an event as protected with the simple tag [["-"]]. A protected event can be accepted only when a relay chooses to support that behavior and verifies that the authenticated publisher is the same pubkey as the event author.

How It Works

The core rule is short. If an event contains the [["-"]] tag, a relay should reject it by default. A relay that wants to support protected events must first run the NIP-42 AUTH flow and confirm that the client who authenticated is publishing their own event.

That makes NIP-70 a publish-authority rule, not an encryption rule. The content can still be readable. What changes is who gets to place that event on a relay that honors the tag. This lets relays support semi-closed feeds and other contexts where authors want a relay to refuse third-party republication.

{
  "id": "cb8feca582979d91fe90455867b34dbf4d65e4b86e86b3c68c368ca9f9eef6f2",
  "pubkey": "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
  "created_at": 1707409439,
  "kind": 1,
  "tags": [
    ["-"]
  ],
  "content": "hello members of the secret group",
  "sig": "fa163f5cfb75d77d9b6269011872ee22b34fb48d23251e9879bb1e4ccbdd8aaaf4b6dc5f5084a65ef42c52fbcde8f3178bac3ba207de827ec513a6aa39fa684c"
}

AUTH Flow Implications

Protected events are useful only when relays actually enforce author identity at publish time. That is why NIP-70 depends so directly on NIP-42. A relay that accepts [["-"]] events without a matching auth check is treating the tag as decoration, not policy.

Relay Behavior and Limits

NIP-70 does not promise that content will stay contained forever. Any recipient can still copy what they see and publish a new event elsewhere. The spec only gives relays a standard way to respect the author’s intent and reject direct republication of protected events.

That is why follow-up work matters. PR #2251 extends the rule to reposts that embed protected events, closing an easy bypass where the original event stayed protected but the wrapper event did not.

Implementations

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See also: