nips/85.md

NIP-85

Trusted Assertions

draft optional

Certain Webs of Trust calculations require access to a large volume of events and/or computing power, making it virtually impossible to perform them directly on clients. This NIP allows users to offload such calculations to declared trusted service providers, and for these providers to publish signed "Trusted Assertion" events for the user client's consumption.

Assertion Events

Trusted Assertions are always addressable (replaceable) events with the d tag pointing to the "subject" of the assertion. This NIP currently recognizes three distinct target "subjects" on which such calculations can be performed: pubkeys, regular events, and addressable events. Each subject type is mapped to an event kind:

Subject	Event Kind	d tag value
User	30382	<pubkey>
Event	30383	<event_id>
Addressable Event	30384	<event_address>
NIP-73 Identifier	30385	<i-tag>

Calculation results are saved in pre-defined tags whose syntax and semantics are agreed upon by providers and clients.

Example of ranking a pubkey with a web of trust score of 89:

{
  "kind": 30382,
  "tags": [
    ["d", "e88a691e98d9987c964521dff60025f60700378a4879180dcbbb4a5027850411"], // target user's public key
    ["rank", "89"],
  ],
  "content": "",
  //...
}

Kind 30382: Users as Subject:

The following result types have been declared:

Result type	Tag name	Tag value format
Follower Count	followers	int
User Rank	rank	int, norm 0-100)
First Post Time	first_created_at	unix timestamp
Post Count	post_cnt	int,
Reply Count	reply_cnt	int
Reactions Count	reactions_cnt	int
Zap Amount Received	zap_amt_recd	int, sats
Zap Amount Sent	zap_amt_sent	int, sats
Zap Number Received	zap_cnt_recd	int
Zap Number Sent	zap_cnt_sent	int
Avg Zap Amount/day recd	zap_avg_amt_day_recd	int, sats
Avg Zap Amount/day sent	zap_avg_amt_day_sent	int, sats
Reports Received	reports_cnt_recd	int
Reports Sent	reports_cnt_sent	int
Common Topics	t	string
Generally active start	active_hours_start	int, 0-24, UTC
Generally active end	active_hours_end	int, 0-24, UTC

Each provider can offer their own ways to calculate such values. For instance, the Follower Count of one trust provider might remove the user's muted public keys while another provider keeps them. Users can then choose how they want to see this information in their preferred client by picking a provider that aligns with their view.

Kind 30383: Events as Subject

Providers can rate individual events with the following tags:

Result type	Tag name	Tag value format
Event Rank	rank	int, norm 0-100
Event Comment Count	comment_cnt	int
Event Quote Count	quote_cnt	int
Event Repost Count	repost_cnt	int
Event Reaction Count	reaction_cnt	int
Event Zap Count	zap_cnt	int
Event Zap Amount	zap_amount	int, sats

Kind 30384: Addressables as Subject

Providers can rate all versions of addressable events using the following tags:

Result type	Tag name	Tag value format
Address Rank	rank	int, norm 0-100
Address Comment Count	comment_cnt	int
Address Quote Count	quote_cnt	int
Address Repost Count	repost_cnt	int
Address Reaction Count	reaction_cnt	int
Address Zap Count	zap_cnt	int
Address Zap Amount	zap_amount	int, sats

Kind 30385: External identifier as Subject

Providers can rate books, locations, movies, websites, and hashtags using NIP-73 identifiers.

Result type	Tag name	Tag value format
Rank	rank	int, norm 0-100
Comment Count	comment_cnt	int
Reaction Count	reaction_cnt	int

NIP-73 k tags should be added to the event as well.

Declaring Trusted Service Providers

Kind 10040 lists the user's authorized providers for each result. Each kind:tag is followed by the pubkey of the service and the relay where the results are published. Users can specify these publicly or privately by JSON-stringifying and encrypting the tag list in the .content using NIP-44.

{
  "kind": 10040,
  "tags": [
    ["30382:rank", "4fd5e210530e4f6b2cb083795834bfe5108324f1ed9f00ab73b9e8fcfe5f12fe", "wss://nip85.nostr.band"],
    ["30382:rank", "3d842afecd5e293f28b6627933704a3fb8ce153aa91d790ab11f6a752d44a42d", "wss://nostr.wine"],
    ["30382:zap_amt_sent", "4fd5e210530e4f6b2cb083795834bfe5108324f1ed9f00ab73b9e8fcfe5f12fe", "wss://nip85.nostr.band"],
  ],
  "content": nip44Encrypt(JSON.stringify([
    ["30383:rank", "4fd5e210530e4f6b2cb083795834bfe5108324f1ed9f00ab73b9e8fcfe5f12fe", "wss://nip85.nostr.band"],
    ["30384:rank", "4fd5e210530e4f6b2cb083795834bfe5108324f1ed9f00ab73b9e8fcfe5f12fe", "wss://nip85.nostr.band"],
  ]),
  //...
}

If the provider offers several algorithms or multiple points of view of an algorithm, the key listed in each tag SHOULD point to the key created for each algorithm or point of view.

Final Considerations

Service providers SHOULD update Trusted Assertions as fast as new information arrives, but only if the contents of each event actually change to avoid re-downloading the same information.

Service providers MAY limit access to the results by using paid relays.

In TAs, p, e, and a tags with the same value as the d tag MAY be used to add a relay hint to the home relay of that user or event.