Encrypt and decrypt using crypto

Cipher.js

const crypto = require('crypto')

const IV_LENGTH = 16
const KEY_LENGTH = 32
const ALGORITHM = 'aes-256-cbc'
const ENCODING = 'hex'
const _privates = Symbol('privates')

/**
 * Encrypt and decrypt text
 *
 * @class Cipher
 */
class Cipher {
  /**
   * Creates an instance of Cipher.
   *
   * @param {String} encriptionKey A key to use for encription
   * @param {Buffer} [iv = crypto.randomBytes(16)] Initialization vector
   * @throws {TypeError} Will throw an exception if `encriptionKey` is undefined
   * @memberof Cipher
   */
  constructor(encriptionKey, iv = crypto.randomBytes(IV_LENGTH)) {
    if (!encriptionKey) {
      throw new TypeError('ENCRYPTION_KEY_REQUIRED')
    }
    this[_privates] = new Map()
    this[_privates].set('iv', iv)
    this[_privates].set('key', encriptionKey)
  }

  /**
   * Encrypt a string
   *
   * @param {String} text String to encrypt
   * @returns {String}
   * @memberof Cipher
   */
  encrypt(text) {
    const cipher = crypto.createCipheriv(
      ALGORITHM,
      Buffer.alloc(KEY_LENGTH, this[_privates].get('key')),
      this[_privates].get('iv')
    )
    let encrypted = cipher.update(text, 'utf-8', ENCODING)
    encrypted += cipher.final(ENCODING)
    return `${this[_privates].get('iv').toString(ENCODING)}:${encrypted}`
  }

  /**
   * Decrypt a string
   *
   * @param {String} text String to decrypt
   * @returns {String}
   * @memberof Cipher
   */
  decrypt(text) {
    const [ivText, encryptedText] = text.split(':')
    const iv = ivText ? new Buffer(ivText, ENCODING) : this[_privates].get('iv')
    const encrypted = new Buffer(encryptedText, ENCODING)
    const decipher = crypto.createDecipheriv(
      ALGORITHM,
      Buffer.alloc(KEY_LENGTH, this[_privates].get('key')),
      iv
    )
    let decrypted = decipher.update(encrypted)
    decrypted = Buffer.concat([decrypted, decipher.final()])
    return decrypted.toString()
  }
}

module.exports = Cipher