Nostr NIPS 59

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NIP-59

Gift Wrap

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This NIP defines a protocol for encapsulating any nostr event. This makes it possible to obscure most metadata for a given event, perform collaborative signing, and more.

This NIP does not define any messaging protocol. Applications of this NIP should be defined separately.

This NIP relies on NIP-44 ’s versioned encryption algorithms.

Overview

This protocol uses three main concepts to protect the transmission of a target event: rumors, seals, and gift wraps.

  • A rumor is a regular nostr event, but is not signed. This means that if it is leaked, it cannot be verified.
  • A rumor is serialized to JSON, encrypted, and placed in the content field of a seal. The seal is then signed by the author of the note. The only information publicly available on a seal is who signed it, but not what was said.
  • A seal is serialized to JSON, encrypted, and placed in the content field of a gift wrap.

This allows the isolation of concerns across layers:

  • A rumor carries the content but is unsigned, which means if leaked it will be rejected by relays and clients, and can’t be authenticated. This provides a measure of deniability.
  • A seal identifies the author without revealing the content or the recipient.
  • A gift wrap can add metadata (recipient, tags, a different author) without revealing the true author.

Protocol Description

1. The Rumor Event Kind

A rumor is the same thing as an unsigned event. Any event kind can be made a rumor by removing the signature.

2. The Seal Event Kind

A seal is a kind:13 event that wraps a rumor with the sender’s regular key. The seal is always encrypted to a receiver’s pubkey but there is no p tag pointing to the receiver. There is no way to know who the rumor is for without the receiver’s or the sender’s private key. The only public information in this event is who is signing it.

{
  "id": "<id>",
  "pubkey": "<real author's pubkey>",
  "content": "<encrypted rumor>",
  "kind": 13,
  "created_at": 1686840217,
  "tags": [],
  "sig": "<real author's pubkey signature>"
}

Tags MUST must always be empty in a kind:13. The inner event MUST always be unsigned.

3. Gift Wrap Event Kind

A gift wrap event is a kind:1059 event that wraps any other event. tags SHOULD include any information needed to route the event to its intended recipient, including the recipient’s p tag or NIP-13 proof of work.

{
  "id": "<id>",
  "pubkey": "<random, one-time-use pubkey>",
  "content": "<encrypted kind 13>",
  "kind": 1059,
  "created_at": 1686840217,
  "tags": [["p", "<recipient pubkey>"]],
  "sig": "<random, one-time-use pubkey signature>"
}

Encrypting Payloads

Encryption is done following NIP-44 on the JSON-encoded event. Place the encryption payload in the .content of the wrapper event (either a seal or a gift wrap).

Other Considerations

If a rumor is intended for more than one party, or if the author wants to retain an encrypted copy, a single rumor may be wrapped and addressed for each recipient individually.

The canonical created_at time belongs to the rumor. All other timestamps SHOULD be tweaked to thwart time-analysis attacks. Note that some relays don’t serve events dated in the future, so all timestamps SHOULD be in the past.

Relays may choose not to store gift wrapped events due to them not being publicly useful. Clients MAY choose to attach a certain amount of proof-of-work to the wrapper event per NIP-13 in a bid to demonstrate that the event is not spam or a denial-of-service attack.

To protect recipient metadata, relays SHOULD guard access to kind 1059 events based on user AUTH. When possible, clients should only send wrapped events to relays that offer this protection.

To protect recipient metadata, relays SHOULD only serve kind 1059 events intended for the marked recipient. When possible, clients should only send wrapped events to read relays for the recipient that implement AUTH, and refuse to serve wrapped events to non-recipients.

An Example

Let’s send a wrapped kind 1 message between two parties asking “Are you going to the party tonight?”

  • Author private key: 0beebd062ec8735f4243466049d7747ef5d6594ee838de147f8aab842b15e273
  • Recipient private key: e108399bd8424357a710b606ae0c13166d853d327e47a6e5e038197346bdbf45
  • Ephemeral wrapper key: 4f02eac59266002db5801adc5270700ca69d5b8f761d8732fab2fbf233c90cbd

Note that this messaging protocol should not be used in practice, this is just an example. Refer to other NIPs for concrete messaging protocols that depend on gift wraps.

1. Create an event

Create a kind 1 event with the message, the receivers, and any other tags you want, signed by the author. Do not sign the event.

{
  "created_at": 1691518405,
  "content": "Are you going to the party tonight?",
  "tags": [],
  "kind": 1,
  "pubkey": "611df01bfcf85c26ae65453b772d8f1dfd25c264621c0277e1fc1518686faef9",
  "id": "9dd003c6d3b73b74a85a9ab099469ce251653a7af76f523671ab828acd2a0ef9"
}

2. Seal the rumor

Encrypt the JSON-encoded rumor with a conversation key derived using the author’s private key and the recipient’s public key. Place the result in the content field of a kind 13 seal event. Sign it with the author’s key.

{
  "content": "AqBCdwoS7/tPK+QGkPCadJTn8FxGkd24iApo3BR9/M0uw6n4RFAFSPAKKMgkzVMoRyR3ZS/aqATDFvoZJOkE9cPG/TAzmyZvr/WUIS8kLmuI1dCA+itFF6+ULZqbkWS0YcVU0j6UDvMBvVlGTzHz+UHzWYJLUq2LnlynJtFap5k8560+tBGtxi9Gx2NIycKgbOUv0gEqhfVzAwvg1IhTltfSwOeZXvDvd40rozONRxwq8hjKy+4DbfrO0iRtlT7G/eVEO9aJJnqagomFSkqCscttf/o6VeT2+A9JhcSxLmjcKFG3FEK3Try/WkarJa1jM3lMRQqVOZrzHAaLFW/5sXano6DqqC5ERD6CcVVsrny0tYN4iHHB8BHJ9zvjff0NjLGG/v5Wsy31+BwZA8cUlfAZ0f5EYRo9/vKSd8TV0wRb9DQ=",
  "kind": 13,
  "created_at": 1703015180,
  "pubkey": "611df01bfcf85c26ae65453b772d8f1dfd25c264621c0277e1fc1518686faef9",
  "tags": [],
  "id": "28a87d7c074d94a58e9e89bb3e9e4e813e2189f285d797b1c56069d36f59eaa7",
  "sig": "02fc3facf6621196c32912b1ef53bac8f8bfe9db51c0e7102c073103586b0d29c3f39bdaa1e62856c20e90b6c7cc5dc34ca8bb6a528872cf6e65e6284519ad73"
}

3. Wrap the seal

Encrypt the JSON-encoded kind 13 event with your ephemeral, single-use random key. Place the result in the content field of a kind 1059. Add a single p tag containing the recipient’s public key. Sign the gift wrap using the random key generated in the previous step.

{
  "content": "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",
  "kind": 1059,
  "created_at": 1703021488,
  "pubkey": "18b1a75918f1f2c90c23da616bce317d36e348bcf5f7ba55e75949319210c87c",
  "id": "5c005f3ccf01950aa8d131203248544fb1e41a0d698e846bd419cec3890903ac",
  "sig": "35fabdae4634eb630880a1896a886e40fd6ea8a60958e30b89b33a93e6235df750097b04f9e13053764251b8bc5dd7e8e0794a3426a90b6bcc7e5ff660f54259"
  "tags": [["p", "166bf3765ebd1fc55decfe395beff2ea3b2a4e0a8946e7eb578512b555737c99"]],
}

4. Broadcast Selectively

Broadcast the kind 1059 event to the recipient’s relays only. Delete all the other events.

Code Samples

JavaScript

import {bytesToHex} from "@noble/hashes/utils"
import type {EventTemplate, UnsignedEvent, Event} from "nostr-tools"
import {getPublicKey, getEventHash, nip19, nip44, finalizeEvent, generateSecretKey} from "nostr-tools"

type Rumor = UnsignedEvent & {id: string}

const TWO_DAYS = 2 * 24 * 60 * 60

const now = () => Math.round(Date.now() / 1000)
const randomNow = () => Math.round(now() - (Math.random() * TWO_DAYS))

const nip44ConversationKey = (privateKey: Uint8Array, publicKey: string) =>
  nip44.v2.utils.getConversationKey(bytesToHex(privateKey), publicKey)

const nip44Encrypt = (data: EventTemplate, privateKey: Uint8Array, publicKey: string) =>
  nip44.v2.encrypt(JSON.stringify(data), nip44ConversationKey(privateKey, publicKey))

const nip44Decrypt = (data: Event, privateKey: Uint8Array) =>
  JSON.parse(nip44.v2.decrypt(data.content, nip44ConversationKey(privateKey, data.pubkey)))

const createRumor = (event: Partial<UnsignedEvent>, privateKey: Uint8Array) => {
  const rumor = {
    created_at: now(),
    content: "",
    tags: [],
    ...event,
    pubkey: getPublicKey(privateKey),
  } as any

  rumor.id = getEventHash(rumor)

  return rumor as Rumor
}

const createSeal = (rumor: Rumor, privateKey: Uint8Array, recipientPublicKey: string) => {
  return finalizeEvent(
    {
      kind: 13,
      content: nip44Encrypt(rumor, privateKey, recipientPublicKey),
      created_at: randomNow(),
      tags: [],
    },
    privateKey
  ) as Event
}

const createWrap = (event: Event, recipientPublicKey: string) => {
  const randomKey = generateSecretKey()

  return finalizeEvent(
    {
      kind: 1059,
      content: nip44Encrypt(event, randomKey, recipientPublicKey),
      created_at: randomNow(),
      tags: [["p", recipientPublicKey]],
    },
    randomKey
  ) as Event
}

// Test case using the above example
const senderPrivateKey = nip19.decode(`nsec1p0ht6p3wepe47sjrgesyn4m50m6avk2waqudu9rl324cg2c4ufesyp6rdg`).data
const recipientPrivateKey = nip19.decode(`nsec1uyyrnx7cgfp40fcskcr2urqnzekc20fj0er6de0q8qvhx34ahazsvs9p36`).data
const recipientPublicKey = getPublicKey(recipientPrivateKey)

const rumor = createRumor(
  {
    kind: 1,
    content: "Are you going to the party tonight?",
  },
  senderPrivateKey
)

const seal = createSeal(rumor, senderPrivateKey, recipientPublicKey)
const wrap = createWrap(seal, recipientPublicKey)

// Recipient unwraps with his/her private key.

const unwrappedSeal = nip44Decrypt(wrap, recipientPrivateKey)
const unsealedRumor = nip44Decrypt(unwrappedSeal, recipientPrivateKey)

Source: nostr-protocol/nips/59.md version: f3589b9 2024-02-01T00:11:14+09:00