Show DevBest [ES6 - JS] Secure Session Management

[MayoMayn]

Well, I saw some folks on here who wanted to get some knowledge about JavaScript from scratch.
I wrote two components for my Electron app, and I then decided just to release them as a separate thread so that other people can enjoy this.

It uses the CryptoJS module by Google for encrypting and decrypting the local storage items.
Auth.js

import CryptoJS from 'crypto-js'
//const CryptoJS = require('crypto-js')
export default class Auth {

  /**
   * Encrypt a string, object or array
   */
  static encrypt(value) {
    // if the value is an object, stringify it so it can be properly encrypted
    if(typeof value === 'object')
      value = JSON.stringify(value)
    // encrypted the value using aes
    let enc = CryptoJS.AES.encrypt(value, 'devbest') // < secret key
    // incase you want to use the encrypted value it gets returned
    return enc.toString()
  }

  /**
   * Decrypt a string, object or array
   */
  static decrypt(value) {
    // decrypts the specified value
    let bytes = CryptoJS.AES.decrypt(value, 'devbest'), // < secret key
        bytesToStr = bytes.toString(CryptoJS.enc.Utf8) // since it returns an object, we're only supposed to receive the decrypted part

    // if the decrypted value is an object, parse it using json
    return (typeof bytesToStr === 'object') ? JSON.parse(bytesToStr) : bytesToStr
  }

}

Session.js

import Auth from './auth'
// const Auth = require('./auth')

export default class Session {

  // writes an object to the local storage
  static write(obj) {
    for(let key in obj) {
      // encrypt the value using the auth class
      obj[key] = Auth.encrypt(obj[key])
      // write the encrypted value to the local storage
      localStorage.setItem(key, obj[key])
    }
 
    // return object incase you want to use it
    return obj
  }
 
  // reads a value from the storage
  static read(key) {
    // decrypt the local storage item using our decrypt method
    return Auth.decrypt(localStorage.getItem(key))
  }

  // checks if several or one item exists in our local storage
  static exists(arr) {
    for(let key in arr) {
      // checks if it exists
      let exists = (localStorage.getItem(arr[key]) !== null)

      if(!exists) return false
    }

    return true
  }

  // remove item in our local storage
  static remove(arr) {
    for(let key in arr) {
      localStorage.removeItem(arr[key])
    }
  }

}

Simple usage:

Session.write({
     username: 'Sentinel',
     bitch: 'Pettyjohn'
})

if(Session.exists(['username', 'bitch']) {
      console.log(Session.read('username'))
      // outputs Sentinel
}