From 7a9d4326862926a2da7277d5cb01d4d559a01bc2 Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Thu, 25 Jan 2024 12:14:51 -0300
Subject: [PATCH] add nip49 key encryption and decryption.

---
 nip19.ts      |  4 +--
 nip49.test.ts | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++
 nip49.ts      | 45 ++++++++++++++++++++++++++
 package.json  |  7 +++-
 4 files changed, 141 insertions(+), 3 deletions(-)
 create mode 100644 nip49.test.ts
 create mode 100644 nip49.ts

diff --git a/nip19.ts b/nip19.ts
index bf416cbb..8ad7c466 100644
--- a/nip19.ts
+++ b/nip19.ts
@@ -3,7 +3,7 @@ import { bech32 } from '@scure/base'
 
 import { utf8Decoder, utf8Encoder } from './utils.ts'
 
-const Bech32MaxSize = 5000
+export const Bech32MaxSize = 5000
 
 /**
  * Bech32 regex.
@@ -175,7 +175,7 @@ function encodeBech32<Prefix extends string>(prefix: Prefix, data: Uint8Array):
   return bech32.encode(prefix, words, Bech32MaxSize) as `${Prefix}1${string}`
 }
 
-function encodeBytes<Prefix extends string>(prefix: Prefix, bytes: Uint8Array): `${Prefix}1${string}` {
+export function encodeBytes<Prefix extends string>(prefix: Prefix, bytes: Uint8Array): `${Prefix}1${string}` {
   return encodeBech32(prefix, bytes)
 }
 
diff --git a/nip49.test.ts b/nip49.test.ts
new file mode 100644
index 00000000..857e8f9f
--- /dev/null
+++ b/nip49.test.ts
@@ -0,0 +1,88 @@
+import { test, expect } from 'bun:test'
+import { decrypt, encrypt } from './nip49'
+import { hexToBytes } from '@noble/hashes/utils'
+
+test('encrypt and decrypt', () => {
+  for (let i = 0; i < vectors.length; i++) {
+    let [password, secret, logn, ksb, ncryptsec] = vectors[i]
+    let sec = hexToBytes(secret)
+    let there = encrypt(sec, password, logn, ksb)
+    let back = decrypt(there, password)
+    let again = decrypt(ncryptsec, password)
+    expect(back).toEqual(again)
+    expect(again).toEqual(sec)
+  }
+})
+
+const vectors: [string, string, number, 0x00 | 0x01 | 0x02, string][] = [
+  [
+    '.ksjabdk.aselqwe',
+    '14c226dbdd865d5e1645e72c7470fd0a17feb42cc87b750bab6538171b3a3f8a',
+    1,
+    0x00,
+    'ncryptsec1qgqeya6cggg2chdaf48s9evsr0czq3dw059t2khf5nvmq03yeckywqmspcc037l9ajjsq2p08480afuc5hq2zq3rtt454c2epjqxcxll0eff3u7ln2t349t7rc04029q63u28mkeuj4tdazsqqk6p5ky',
+  ],
+  [
+    'skjdaklrnçurbç l',
+    'f7f2f77f98890885462764afb15b68eb5f69979c8046ecb08cad7c4ae6b221ab',
+    2,
+    0x01,
+    'ncryptsec1qgp86t7az0u5w0wp8nrjnxu9xhullqt39wvfsljz8289gyxg0thrlzv3k40dsqu32vcqza3m7srzm27mkg929gmv6hv5ctay59jf0h8vsj5pjmylvupkdtvy7fy88et3fhe6m3d84t9m8j2umq0j75lw',
+  ],
+  [
+    '777z7z7z7z7z7z7z',
+    '11b25a101667dd9208db93c0827c6bdad66729a5b521156a7e9d3b22b3ae8944',
+    3,
+    0x02,
+    'ncryptsec1qgpc7jmmzmds376r8slazywlagrm5eerlrx7njnjenweggq2atjl0h9vmpk8f9gad0tqy3pwch8e49kyj5qtehp4mjwpzlshx5f5cce8feukst08w52zf4a7gssdqvt3eselup7x4zzezlme3ydxpjaf',
+  ],
+  [
+    '.ksjabdk.aselqwe',
+    '14c226dbdd865d5e1645e72c7470fd0a17feb42cc87b750bab6538171b3a3f8a',
+    7,
+    0x00,
+    'ncryptsec1qgrss6ycqptee05e5anq33x2vz6ljr0rqunsy9xj5gypkp0lucatdf8yhexrztqcy76sqweuzk8yqzep9mugp988vznz5df8urnyrmaa7l7fvvskp4t0ydjtz0zeajtumul8cnsjcksp68xhxggmy4dz',
+  ],
+  [
+    'skjdaklrnçurbç l',
+    'f7f2f77f98890885462764afb15b68eb5f69979c8046ecb08cad7c4ae6b221ab',
+    8,
+    0x01,
+    'ncryptsec1qgy0gg98z4wvl35eqlraxf7cyxhfs4968teq59vm97e94gpycmcy6znsc8z82dy5rk8sz0r499ue7xfmd0yuyvzxagtfyxtnwcrcsjavkch8lfseejukwdq7mdcpm43znffngw7texdc5pdujywszhrr',
+  ],
+  [
+    '777z7z7z7z7z7z7z',
+    '11b25a101667dd9208db93c0827c6bdad66729a5b521156a7e9d3b22b3ae8944',
+    9,
+    0x02,
+    'ncryptsec1qgyskhh7mpr0zspg95kv4eefm8233hyz46xyr6s52s6qvan906c2u24gl3dc5f7wytzq9njx7sqksd7snagce3kqth7tv4ug4avlxd5su4vthsh54vk62m88whkazavyc6yefnegf4tx473afssxw4p9',
+  ],
+  [
+    '',
+    'f7f2f77f98890885462764afb15b68eb5f69979c8046ecb08cad7c4ae6b221ab',
+    4,
+    0x00,
+    'ncryptsec1qgzv73a9ktnwmgyvv24x2xtr6grup2v6an96xgs64z3pmh5etg2k4yryachtlu3tpqwqphhm0pjnq9zmftr0qf4p5lmah4rlz02ucjkawr2s9quau67p3jq3d7yp3kreghs0wdcqpf6pkc8jcgsqrn5l',
+  ],
+  [
+    '',
+    '11b25a101667dd9208db93c0827c6bdad66729a5b521156a7e9d3b22b3ae8944',
+    5,
+    0x01,
+    'ncryptsec1qgzs50vjjhewdrxnm0z4y77w7juycf6crny9q0kzeg7vxv3erw77qpauthaf7sfwsgnszjzcqh7zql74m8yxnhcj07dry3v5fgr5x42mpzxvfl76gpuayccvk2nczc7ner3q842rj9v033nykvja6cql',
+  ],
+  [
+    '',
+    'f7f2f77f98890885462764afb15b68eb5f69979c8046ecb08cad7c4ae6b221ab',
+    1,
+    0x00,
+    'ncryptsec1qgqnx59n7duv6ec3hhrvn33q25u2qfd7m69vv6plsg7spnw6d4r9hq0ayjsnlw99eghqqzj8ps7vfwx40nqp9gpw7yzyy09jmwkq3a3z8q0ph5jahs2hap5k6h2wfrme7w2nuek4jnwpzfht4q3u79ra',
+  ],
+  [
+    '',
+    '11b25a101667dd9208db93c0827c6bdad66729a5b521156a7e9d3b22b3ae8944',
+    9,
+    0x01,
+    'ncryptsec1qgylzyeunu2j85au05ae0g0sly03xu54tgnjemr6g9w0eqwuuczya7k0f4juqve64vzsrlxqxmcekzrpvg2a8qu4q6wtjxe0dvy3xkjh5smmz4uy59jg0jay9vnf28e3rc6jq2kd26h6g3fejyw6cype',
+  ],
+]
diff --git a/nip49.ts b/nip49.ts
new file mode 100644
index 00000000..470e766c
--- /dev/null
+++ b/nip49.ts
@@ -0,0 +1,45 @@
+import { scrypt } from '@noble/hashes/scrypt'
+import { xchacha20poly1305 } from '@noble/ciphers/chacha'
+import { concatBytes, randomBytes } from '@noble/hashes/utils'
+import { Bech32MaxSize, encodeBytes } from './nip19'
+import { bech32 } from '@scure/base'
+
+export function encrypt(sec: Uint8Array, password: string, logn: number = 16, ksb: 0x00 | 0x01 | 0x02 = 0x02): string {
+  let salt = randomBytes(16)
+  let n = 2 ** logn
+  let key = scrypt(password, salt, { N: n, r: 8, p: 1, dkLen: 32 })
+  let nonce = randomBytes(24)
+  let aad = Uint8Array.from([ksb])
+  let xc2p1 = xchacha20poly1305(key, nonce, aad)
+  let ciphertext = xc2p1.encrypt(sec)
+  let b = concatBytes(Uint8Array.from([0x02]), Uint8Array.from([logn]), salt, nonce, aad, ciphertext)
+  return encodeBytes('ncryptsec', b)
+}
+
+export function decrypt(ncryptsec: string, password: string): Uint8Array {
+  let { prefix, words } = bech32.decode(ncryptsec, Bech32MaxSize)
+  if (prefix !== 'ncryptsec') {
+    throw new Error(`invalid prefix ${prefix}, expected 'ncryptsec'`)
+  }
+  let b = new Uint8Array(bech32.fromWords(words))
+
+  let version = b[0]
+  if (version !== 0x02) {
+    throw new Error(`invalid version ${version}, expected 0x02`)
+  }
+
+  let logn = b[1]
+  let n = 2 ** logn
+
+  let salt = b.slice(2, 2 + 16)
+  let nonce = b.slice(2 + 16, 2 + 16 + 24)
+  let ksb = b[2 + 16 + 24]
+  let aad = Uint8Array.from([ksb])
+  let ciphertext = b.slice(2 + 16 + 24 + 1)
+
+  let key = scrypt(password, salt, { N: n, r: 8, p: 1, dkLen: 32 })
+  let xc2p1 = xchacha20poly1305(key, nonce, aad)
+  let sec = xc2p1.decrypt(ciphertext)
+
+  return sec
+}
diff --git a/package.json b/package.json
index 7b175719..48e34e7a 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "type": "module",
   "name": "nostr-tools",
-  "version": "2.1.5",
+  "version": "2.1.6",
   "description": "Tools for making a Nostr client.",
   "repository": {
     "type": "git",
@@ -150,6 +150,11 @@
       "require": "./lib/cjs/nip44.js",
       "types": "./lib/types/nip44.d.ts"
     },
+    "./nip49": {
+      "import": "./lib/esm/nip49.js",
+      "require": "./lib/cjs/nip49.js",
+      "types": "./lib/types/nip49.d.ts"
+    },
     "./nip57": {
       "import": "./lib/esm/nip57.js",
       "require": "./lib/cjs/nip57.js",