3box/src/3id/keyring.js

Interact with user data

const { HDNode } = require('@ethersproject/hdnode')
const nacl = require('tweetnacl')
nacl.util = require('tweetnacl-util')
const SimpleSigner = require('did-jwt').SimpleSigner
const { sha256 } = require('../utils/index')
const EC = require('elliptic').ec
const ec = new EC('secp256k1')
const { randomNonce, symEncryptBase, symDecryptBase }  = require('./utils')

const BASE_PATH = "m/7696500'/0'/0'"
const MM_PATH = "m/44'/60'/0'/0"

class Keyring {
  constructor (seed) {
    this._seed = seed
    const seedNode = HDNode.fromSeed(this._seed)
    const baseNode = seedNode.derivePath(BASE_PATH)

    this.signingKey = baseNode.derivePath("0")
    const tmpEncKey = Buffer.from(baseNode.derivePath("2").privateKey.slice(2), 'hex')
    this.asymEncryptionKey = nacl.box.keyPair.fromSecretKey(new Uint8Array(tmpEncKey))
    this.symEncryptionKey = new Uint8Array(Buffer.from(baseNode.derivePath("3").privateKey.slice(2), 'hex'))

    this.ethereumKey = seedNode.derivePath(MM_PATH).derivePath("0")
  }

  asymEncrypt (msg, toPublic, nonce) {
    nonce = nonce || randomNonce()
    toPublic = nacl.util.decodeBase64(toPublic)
    if (typeof msg === 'string') {
      msg = nacl.util.decodeUTF8(msg)
    }
    const ephemneralKeypair = nacl.box.keyPair()
    const ciphertext = nacl.box(msg, nonce, toPublic, ephemneralKeypair.secretKey)
    return {
      nonce: nacl.util.encodeBase64(nonce),
      ephemeralFrom: nacl.util.encodeBase64(ephemneralKeypair.publicKey),
      ciphertext: nacl.util.encodeBase64(ciphertext)
    }
  }

  asymDecrypt (ciphertext, fromPublic, nonce, toBuffer) {
    fromPublic = nacl.util.decodeBase64(fromPublic)
    ciphertext = nacl.util.decodeBase64(ciphertext)
    nonce = nacl.util.decodeBase64(nonce)
    const cleartext = nacl.box.open(ciphertext, nonce, fromPublic, this.asymEncryptionKey.secretKey)
    if (toBuffer) {
      return cleartext ? Buffer.from(cleartext) : null
    }
    return cleartext ? nacl.util.encodeUTF8(cleartext) : null
  }

  symEncrypt (msg, nonce) {
    return symEncryptBase(msg, this.symEncryptionKey, nonce)
  }

  symDecrypt (ciphertext, nonce, toBuffer) {
    return symDecryptBase(ciphertext, this.symEncryptionKey, nonce, toBuffer)
  }

  getJWTSigner () {
    return SimpleSigner(this.signingKey.privateKey.slice(2))
  }

  getDBSalt () {
    return sha256(this.signingKey.derivePath('0').privateKey.slice(2))
  }

  getPublicKeys (uncompressed) {
    let signingKey = this.signingKey.publicKey.slice(2)
    let ethereumKey = this.ethereumKey.publicKey.slice(2)
    if (uncompressed) {
      signingKey = Keyring.uncompress(signingKey)
      ethereumKey = Keyring.uncompress(ethereumKey)
    }
    return {
      signingKey,
      ethereumKey,
      asymEncryptionKey: nacl.util.encodeBase64(this.asymEncryptionKey.publicKey)
    }
  }

  serialize () {
    return this._seed
  }

  static uncompress (key) {
    return ec.keyFromPublic(Buffer.from(key, 'hex')).getPublic(false, 'hex')
  }
}

module.exports = Keyring