How to encrypt file using express multer

Question

By having these simple few lines of code I've got file saved on server.

router.post('/upload',  upload.single('file'), function(req: Request, res: Response, next: Function) {
    console.log(req.file);
    res.json({ success: true, message: 'Uploaded' });
});

I want to encrypt the file before it is get saved.

Is there any way I can do that?

Answer 1

One way for encrypting files is with Buffers using multer's memoryStorage() and Node.js built-in crypto library.

import multer from 'multer'
import { scryptSync, createCipheriv } from 'crypto'
import { mkdirSync, existsSync, writeFileSync } from 'fs'

const upload = multer({ storage: multer.memoryStorage() })

const encrypt = (buffer) => {
  // More info: https://nodejs.org/api/crypto.html
  const algorithm = 'aes-192-cbc'
  const iv = Buffer.alloc(16, 0)
  const key = scryptSync('super strong password', 'salt', 24)

  const cipher = createCipheriv(algorithm, key, iv)
  return Buffer.concat([cipher.update(buffer), cipher.final()])
}

const saveEncryptedFile = (buffer, filePath) => {
  if (!existsSync(path.dirname(filePath))) {
    mkdirSync(path.dirname(filePath))
  }
  writeFileSync(filePath, encrypt(buffer))
}

router.post('/upload', upload.single('file'), ({ file }, res, next) => {
  saveEncryptedFile(file.buffer, './your-file-path')
})