streamToPromise.js

const streamAsPromise = (readable) => {
  const result = []
  const w = new Writable({
    write(chunk, encoding, callback) {·
      result.push(chunk)
      callback()
    }
  })
  readable.pipe(w)
  return new Promise((resolve, reject) => {
    w.on('finish', resolve)
    w.on('error', reject)
  }).then(() => result.join(''))
}

var r = fs.createReadStream('secrets');
const c = new CollectToPromise()
const encrypt = crypto.createCipher(algorithm, password);
//r.pipe(encrypt).pipe(c).asPromise()
streamAsPromise(r.pipe(encrypt))
  .then((res) => console.log(res))