nips/63.md

NIP-63
======

Signed Filters
--------------

`draft` `optional`

Event kind `33012` is used to represent one or more Nostr filters. 

The `d` tag represents the subscription id and the `filter` tag contains the JSON-stringified [NIP-01](01.md) filter. 

```js
{
  "kind": 33012,
  "tags": [
    ["d", "<subscription_id>"],
    ["relay", "<relay>"],
    ["filter", "<filter1>"],
    ["filter", "<filter2>"],
    ["expiration", "<unix timestamp>"],
  ],
  "content": "",
  // ...other fields
}
```

They are submitted to supporting relays via `SREQ` command, with the following format: 

```js
["SREQ", <signed kind-33012>]
```

Supporting relays interpret the `filter` tags in the same way they do with `REQ` while automatically authenticating the signer. 

Relays MAY reject these filters based on `created_at`. 

An expiration tag MAY be used to limit the reuse of the filter. 

## Motivation

The goal is to be able to support `AUTH` from multiple users in the same connection. As a side effect, this approach removes the `AUTH` round trip. 

Trusted proxies can use these event types to query relays on behalf of the user. 

Push Notification systems can use these events to download events from private relays and push them down to mobile phones.