# ActivityPub federation in Mitra

Mitra largely follows the [ActivityPub](https://www.w3.org/TR/activitypub/) server-to-server specification but it makes uses of some non-standard extensions, some of which are required for interacting with it.

The following activities are supported:

- Accept(Follow)
- Reject(Follow)
- Undo(Follow)
- Create(Note)
- Delete(Note)
- Like(Note)
- Undo(Like)
- Announce(Note)
- Undo(Announce)
- Follow(Person)
- Update(Person)
- Delete(Person)

And these additional standards:

- [Http Signatures](https://datatracker.ietf.org/doc/html/draft-cavage-http-signatures)
- [NodeInfo](https://nodeinfo.diaspora.software/)
- [WebFinger](https://webfinger.net/)

Activities are implemented in way that is compatible with Pleroma, Mastodon and other popular ActivityPub servers.

## Profile extensions

### Cryptocurrency addresses

Cryptocurrency addresses are represented as `PropertyValue` attachments where `name` attribute is a currency symbol prefixed with `$`:

```json
{
  "name": "$XMR",
  "type": "PropertyValue",
  "value": "8Ahza5RM4JQgtdqvpcF1U628NN5Q87eryXQad3Fy581YWTZU8o3EMbtScuioQZSkyNNEEE1Lkj2cSbG4VnVYCW5L1N4os5p"
}
```

### Identity proofs

Identity proofs are represented as attachments of `IdentityProof` type:

```json
{
  "name": "<did>",
  "type": "IdentityProof",
  "signatureAlgorithm": "<proof-type>",
  "signatureValue": "<proof>"
}
```