Merge branch 'pr/183'

util/crypto.js

@@ -1,4 +1,5 @@
 const CryptoJS = require('crypto-js')
+const crypto = require('crypto')
 const forge = require('node-forge')
 const zlib = require('zlib')
 const iv = '0102030405060708'
@@ -9,6 +10,13 @@ const publicKey = `-----BEGIN PUBLIC KEY-----
 MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDgtQn2JZ34ZC28NWYpAUd98iZ37BUrX/aKzmFbt7clFSs6sXqHauqKWqdtLkF2KexO40H1YTX8z2lSgBBOAxLsvaklV8k4cBFK9snQXE9/DDaFt6Rr7iVZMldczhC0JNgTz+SHXT6CBHuX3e9SdB1Ua44oncaTWz7OBGLbCiK45wIDAQAB
 -----END PUBLIC KEY-----`
 const eapiKey = 'e82ckenh8dichen8'
+const xeapiStaticKey = Buffer.from(
+  'ab1d5a430f6bb04a3f01e81ddd72bd916d5ce591248ac128714806d7f8fb1b84',
+  'hex',
+)
+const xeapiSignKey =
+  'mUHCwVNWJbunMqAHf5MImuirT6plvs6VSFW62MGHstFQxhBGdEoIhLItH3djc4+FB/OKty3+lL2rGeoFBpVe5g=='
+const x25519SpkiPrefix = Buffer.from('302a300506032b656e032100', 'hex')
 
 const aesEncrypt = (text, mode, key, iv, format = 'base64') => {
   let encrypted = CryptoJS.AES.encrypt(
@@ -141,13 +149,172 @@ const decrypt = (cipher) => {
   return decryptedBytes
 }
 
+const aesEcbEncrypt = (key, plaintext) => {
+  const cipher = crypto.createCipheriv(`aes-${key.length * 8}-ecb`, key, null)
+  return Buffer.concat([cipher.update(Buffer.from(plaintext)), cipher.final()])
+}
+
+const aesEcbDecrypt = (key, ciphertext) => {
+  const decipher = crypto.createDecipheriv(
+    `aes-${key.length * 8}-ecb`,
+    key,
+    null,
+  )
+  return Buffer.concat([decipher.update(ciphertext), decipher.final()])
+}
+
+const createX25519PublicKey = (raw) => {
+  // Node's crypto API expects X25519 public keys as DER SubjectPublicKeyInfo.
+  // The Android SDK stores only the 32-byte raw key, so prepend the fixed
+  // RFC 8410 SPKI header for id-X25519 before importing it.
+  return crypto.createPublicKey({
+    key: Buffer.concat([x25519SpkiPrefix, raw]),
+    format: 'der',
+    type: 'spki',
+  })
+}
+
+const deriveX25519AesKey = (sharedSecret, ephemeralPublicKey) => {
+  const prk = crypto
+    .createHmac('sha256', Buffer.alloc(32))
+    .update(sharedSecret.length ? sharedSecret : Buffer.alloc(32))
+    .digest()
+  return crypto
+    .createHmac('sha256', prk)
+    .update(Buffer.concat([ephemeralPublicKey, Buffer.from([1])]))
+    .digest()
+    .subarray(0, 16)
+}
+
+const xeapiSign = (timestamp, nonce) => {
+  return crypto
+    .createHmac('sha256', xeapiSignKey)
+    .update(String(timestamp) + nonce)
+    .digest('base64')
+}
+
+const xeapiMidTransform = (ciphertext) => {
+  const random = crypto.randomBytes(16)
+  const xored = Buffer.alloc(ciphertext.length)
+  for (let i = 0; i < ciphertext.length; i++) {
+    xored[i] = ciphertext[i] ^ random[i & 0x0f]
+  }
+  const b64 = Buffer.from(xored.toString('base64'))
+  const rot = b64.length ? (random[0] & 0x0f) % b64.length : 0
+  return Buffer.concat([random, b64.subarray(rot), b64.subarray(0, rot)])
+}
+
+const xeapiEncryptS = (dynamicKey, publicKeyState, os) => {
+  const peerRaw = Buffer.from(publicKeyState.publicKey, 'base64')
+  const peerKey = createX25519PublicKey(peerRaw)
+  const { publicKey, privateKey } = crypto.generateKeyPairSync('x25519')
+  const ephemeralRaw = Buffer.from(
+    publicKey.export({ format: 'der', type: 'spki' }),
+  ).subarray(-32)
+  const sharedSecret = crypto.diffieHellman({
+    privateKey,
+    publicKey: peerKey,
+  })
+  const aesKey = deriveX25519AesKey(sharedSecret, ephemeralRaw)
+  const iv = crypto.randomBytes(12)
+  const cipher = crypto.createCipheriv('aes-128-gcm', aesKey, iv)
+  const plaintext = Buffer.from(
+    `${dynamicKey.toString('base64')}|${os}|${publicKeyState.sk || ''}`,
+  )
+  const encrypted = Buffer.concat([cipher.update(plaintext), cipher.final()])
+  return Buffer.concat([ephemeralRaw, iv, encrypted, cipher.getAuthTag()])
+}
+
+const buildXeapiPlaintext = (uri, data, options = {}) => {
+  const fields = {}
+  const contentType =
+    options.contentType || 'application/x-www-form-urlencoded;charset=utf-8'
+  const mediaType = contentType.split(';', 1)[0].toLowerCase()
+  if (mediaType !== 'application/x-www-form-urlencoded') {
+    fields.contentType = contentType
+  }
+
+  const method = (options.method || 'POST').toUpperCase()
+  if (method !== 'POST') fields.method = method
+
+  const url = new URL(uri, 'https://interface.music.163.com')
+  if (url.search) fields.queryString = url.search.slice(1)
+
+  if (data !== undefined && data !== null) {
+    const bodyData = { ...data }
+    delete bodyData.e_r
+    const body = Buffer.from(new URLSearchParams(bodyData).toString())
+    fields.body = body.toString('base64')
+  }
+
+  if (fields.queryString) {
+    fields.queryString += '&e_r=true'
+  } else {
+    fields.queryString = 'e_r=true'
+  }
+  return JSON.stringify(fields)
+}
+
+const xeapi = (uri, data, options = {}) => {
+  const publicKeyState = options.publicKeyState
+  if (!publicKeyState) {
+    throw new Error('xeapi publicKeyState is required')
+  }
+  const activeSessionKey = options.sessionKey
+    ? Buffer.from(String(options.sessionKey))
+    : null
+  const activeSessionId = options.sessionId || ''
+  const dynamicKey = activeSessionKey || crypto.randomBytes(16)
+  const plaintext = Buffer.from(buildXeapiPlaintext(uri, data, options))
+
+  const b = aesEcbEncrypt(
+    dynamicKey,
+    xeapiMidTransform(aesEcbEncrypt(xeapiStaticKey, plaintext)),
+  )
+  const s = xeapiEncryptS(dynamicKey, publicKeyState, options.os || 'android')
+  const r = aesEcbEncrypt(
+    xeapiStaticKey,
+    Buffer.from(
+      `${publicKeyState.version}|${activeSessionKey ? activeSessionId : ''}`,
+    ),
+  )
+
+  return {
+    B: b.toString('base64'),
+    S: s.toString('base64'),
+    R: r.toString('base64'),
+  }
+}
+
+const xeapiResDecrypt = (body) => {
+  const decrypted = aesEcbDecrypt(eapiKey, body)
+  const plaintext =
+    decrypted[0] === 0x1f && decrypted[1] === 0x8b
+      ? zlib.gunzipSync(decrypted)
+      : decrypted
+  return JSON.parse(plaintext.toString())
+}
+
+const xeapiDecryptPublicKey = (encryptedData) => {
+  return JSON.parse(
+    aesEcbDecrypt(
+      xeapiStaticKey,
+      Buffer.from(encryptedData, 'base64'),
+    ).toString(),
+  )
+}
+
 module.exports = {
   weapi,
   linuxapi,
   eapi,
+  xeapi,
   decrypt,
   aesEncrypt,
   aesDecrypt,
   eapiReqDecrypt,
   eapiResDecrypt,
+  xeapiSign,
+  xeapiResDecrypt,
+  xeapiDecryptPublicKey,
 }