text: const crypto = require('./crypto')
  
  class CTR {
      constructor(key, iv) {
          if (!Buffer.isBuffer(key) || !Buffer.isBuffer(iv) || iv.length !== 16) {
              throw new Error('Key and iv need to be a buffer')
          }
  
          this.cipher = crypto.createCipheriv('AES-256-CTR', key, iv)
      }
  
      encrypt(data) {
          return Buffer.from(this.cipher.update(data))
      }
  }
  
  module.exports = CTR
  