From 482c5affd426bcd6dd791028981daaabc8d73c02 Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Tue, 20 Dec 2022 18:26:30 -0300
Subject: [PATCH] add nip19.

---
 index.ts      |   1 +
 nip19.test.js |  36 +++++++++++++++
 nip19.ts      | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++
 package.json  |   1 +
 4 files changed, 164 insertions(+)
 create mode 100644 nip19.test.js
 create mode 100644 nip19.ts

diff --git a/index.ts b/index.ts
index 2c1212b..aef3274 100644
--- a/index.ts
+++ b/index.ts
@@ -6,3 +6,4 @@ export * from './filter'
 export * as nip04 from './nip04'
 export * as nip05 from './nip05'
 export * as nip06 from './nip06'
+export * as nip19 from './nip19'
diff --git a/nip19.test.js b/nip19.test.js
new file mode 100644
index 0000000..e3dc252
--- /dev/null
+++ b/nip19.test.js
@@ -0,0 +1,36 @@
+/* eslint-env jest */
+
+const {nip19, generatePrivateKey, getPublicKey} = require('./lib/nostr.cjs')
+
+test('encode and decode nsec', () => {
+  let sk = generatePrivateKey()
+  let nsec = nip19.nsecEncode(sk)
+  expect(nsec).toMatch(/nsec1\w+/)
+  let {type, data} = nip19.decode(nsec)
+  expect(type).toEqual('nsec')
+  expect(data).toEqual(sk)
+})
+
+test('encode and decode npub', () => {
+  let pk = getPublicKey(generatePrivateKey())
+  let npub = nip19.npubEncode(pk)
+  expect(npub).toMatch(/npub1\w+/)
+  let {type, data} = nip19.decode(npub)
+  expect(type).toEqual('npub')
+  expect(data).toEqual(pk)
+})
+
+test('encode and decode nprofile', () => {
+  let pk = getPublicKey(generatePrivateKey())
+  let relays = [
+    'wss://relay.nostr.example.mydomain.example.com',
+    'wss://nostr.banana.com'
+  ]
+  let nprofile = nip19.nprofileEncode({pubkey: pk, relays})
+  expect(nprofile).toMatch(/nprofile1\w+/)
+  let {type, data} = nip19.decode(nprofile)
+  expect(type).toEqual('nprofile')
+  expect(data.pubkey).toEqual(pk)
+  expect(data.relays).toContain(relays[0])
+  expect(data.relays).toContain(relays[1])
+})
diff --git a/nip19.ts b/nip19.ts
new file mode 100644
index 0000000..be44135
--- /dev/null
+++ b/nip19.ts
@@ -0,0 +1,126 @@
+import * as secp256k1 from '@noble/secp256k1'
+import {bech32} from 'bech32'
+
+type ProfilePointer = {
+  pubkey: string // hex
+  relays?: string[]
+}
+
+type EventPointer = {
+  id: string // hex
+  relays?: string[]
+}
+
+let utf8Decoder = new TextDecoder('utf-8')
+let utf8Encoder = new TextEncoder()
+
+export function decode(nip19: string): {
+  type: string
+  data: ProfilePointer | EventPointer | string
+} {
+  let {prefix, words} = bech32.decode(nip19, 1000)
+  let data = new Uint8Array(bech32.fromWords(words))
+
+  if (prefix === 'nprofile') {
+    let tlv = parseTLV(data)
+    if (!tlv[0]?.[0]) throw new Error('missing TLV 0 for nprofile')
+    if (tlv[0][0].length !== 32) throw new Error('TLV 0 should be 32 bytes')
+
+    return {
+      type: 'nprofile',
+      data: {
+        pubkey: secp256k1.utils.bytesToHex(tlv[0][0]),
+        relays: tlv[1].map(d => utf8Decoder.decode(d))
+      }
+    }
+  }
+
+  if (prefix === 'nevent') {
+    let tlv = parseTLV(data)
+    if (!tlv[0]?.[0]) throw new Error('missing TLV 0 for nevent')
+    if (tlv[0][0].length !== 32) throw new Error('TLV 0 should be 32 bytes')
+
+    return {
+      type: 'nevent',
+      data: {
+        id: secp256k1.utils.bytesToHex(tlv[0][0]),
+        relays: tlv[1].map(d => utf8Decoder.decode(d))
+      }
+    }
+  }
+
+  if (prefix === 'nsec' || prefix === 'npub' || prefix === 'note') {
+    return {type: prefix, data: secp256k1.utils.bytesToHex(data)}
+  }
+
+  throw new Error(`unknown prefix ${prefix}`)
+}
+
+type TLV = {[t: number]: Uint8Array[]}
+
+function parseTLV(data: Uint8Array): TLV {
+  let result: TLV = {}
+  let rest = data
+  while (rest.length > 0) {
+    let t = rest[0]
+    let l = rest[1]
+    let v = rest.slice(2, 2 + l)
+    rest = rest.slice(2 + l)
+    if (v.length < l) continue
+    result[t] = result[t] || []
+    result[t].push(v)
+  }
+  return result
+}
+
+export function nsecEncode(hex: string): string {
+  return encodeBytes('nsec', hex)
+}
+
+export function npubEncode(hex: string): string {
+  return encodeBytes('npub', hex)
+}
+
+export function noteEncode(hex: string): string {
+  return encodeBytes('note', hex)
+}
+
+function encodeBytes(prefix: string, hex: string): string {
+  let data = secp256k1.utils.hexToBytes(hex)
+  let words = bech32.toWords(data)
+  return bech32.encode(prefix, words, 1000)
+}
+
+export function nprofileEncode(profile: ProfilePointer): string {
+  let data = encodeTLV({
+    0: [secp256k1.utils.hexToBytes(profile.pubkey)],
+    1: (profile.relays || []).map(url => utf8Encoder.encode(url))
+  })
+  let words = bech32.toWords(data)
+  return bech32.encode('nprofile', words, 1000)
+}
+
+export function neventEncode(event: EventPointer): string {
+  let data = encodeTLV({
+    0: [secp256k1.utils.hexToBytes(event.id)],
+    1: (event.relays || []).map(url => utf8Encoder.encode(url))
+  })
+  let words = bech32.toWords(data)
+  return bech32.encode('nevent', words, 1000)
+}
+
+function encodeTLV(tlv: TLV): Uint8Array {
+  let entries: Uint8Array[] = []
+
+  Object.entries(tlv).forEach(([t, vs]) => {
+    vs.forEach(v => {
+      let entry = new Uint8Array(v.length + 2)
+      entry.set([parseInt(t)], 0)
+      entry.set([v.length], 1)
+      entry.set(v, 2)
+      entries.push(entry)
+    })
+  })
+
+  return secp256k1.utils.concatBytes(...entries)
+}
diff --git a/package.json b/package.json
index 675766d..a53b741 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
     "@noble/secp256k1": "^1.7.0",
     "@scure/bip32": "^1.1.1",
     "@scure/bip39": "^1.1.0",
+    "bech32": "^2.0.0",
     "browserify-cipher": ">=1",
     "buffer": "^6.0.3",
     "websocket-polyfill": "^0.0.3"