nips/81.md

NIP-81
======

Relationship Status
-------------------

`draft` `optional`

This NIP defines two new event kinds (`30382` and `30383`) to document the relationship between two keys. 

Both kinds offer public and private tags to describe that relationship. Private tags are JSON Stringified, [NIP-44](44.md)-encrypted to the signer's keys and placed inside the `.content` of the event. 

### Public Relationship Status

Event kind `30382` is used when the relationship itself is public. The `d` tag contains the target public key in hex.

```js
{
  "kind": 30382,
  "tags": [
    ["d", "e88a691e98d9987c964521dff60025f60700378a4879180dcbbb4a5027850411"],
    ["n", "follow"],
    ["n", "bitcoiner"],
    ["n", "6064460175057025"]
  ],
  "content": nip44Encrypt(JSON.stringify([
    ["petname", "NVK (Coldcard)"],
    ["summary", "Owes me a beer"]
  ])),
  // ...other fields
}
```

`petname` SHOULD be rendered instead of the person's display name in all interfaces when the signer of this event is logged in.

### Relationship Categories

Optional `n` tags `["n", "<identifier>"]` add the target key to event sets. This allows clients to query by `n` and download all members of a set. 

Set `identifier` can be human readable and public or not. 

For private cases, a new event kind named "Event Set Names" (`kind:10008`) uses `map` tags to store the set name. Clients SHOULD display the `name` instead of the `identifier` if the `identifier` is present in this event.

```js
{
  "kind": 10008,
  "content": nip44Encrypt(JSON.stringify([
    ["map", "<identifier>", "<name>"],
    ["map", "bitcoiner", "bitcoiner"], 
    ["map", "6064460175057025", "debtor"]
  ])),
  // ...other fields
}
```

### Private Relationship Status

For relationships that must remain private (e.g private follows, client lists, etc), the event kind `30383` uses a similar structure but with a hashed `d` tag using [NIP-44](44.md)'s `hkdf` function. 

```js
{
  "kind": 30383,
  "tags": [
    ["d", sha256(hkdf(private_key, salt: 'nip81') || "<pubkey>")],
    ["n", "6064460175057025"],
  ],
  "content": nip44Encrypt(JSON.stringify([
    ["p", "<pubkey>", "<relay url>"],
    ["n", "client-list"],
    ["petname", "<My buddy>"],
    ["summary", "<Summary of the relationship>"],
  ])),
  // ...other fields
}
```