nacl-blob

Encrypt and decrypt DOM blobs using nacl-stream within service workers. A port of nacl-stream-js's demo into a consumable module.

• 🌎 Example site

Usage

const naclBlob = require('nacl-blob')
const nacl = require('tweetnacl')
 
const key = nacl.box.keyPair().secretKey
const nonce = nacl.randomBytes(16)
 
// Any kind of data inside of a blob
const arr = new Uint8Array(10 * 1024 * 1024 + 111)
for (let i = 0; i < arr.length; i++) arr[i] = i & 0xff
const blob = new Blob([arr])
 
const encryptor = naclBlob.encrypt(key, nonce, blob, (err, encryptedBlob) => {
  if (err) throw (err)
  // some time later
  const decryptor = naclBlob.decrypt(key, nonce, encryptedBlob, (err, decryptedBlob) => {
    if (err) throw (err)
    compareBlobs(blob, decryptedBlob)
  })
  decryptor.on('progress', ({position, length}) => { console.log('decrypting %' + (position / length) * 100) })
})
 
encryptor.on('progress', ({position, length}) => { console.log('encrypting %' + (position / length) * 100) })
 
 
function compareBlobs (a, b) {
  const r1 = new FileReader()
  r1.onload = function () {
    const r2 = new FileReader()
    r2.onload = function () {
      if (r1.result !== r2.result) {
        console.error('blobs differ')
      } else {
        console.log('blobs are equal')
      }
    }
    r2.readAsBinaryString(b)
  }
  r1.readAsBinaryString(a)
}

API

encrypt = require('nacl-blob').encrypt

Import the encrypt function.

decrypt = require('nacl-blob').decrypt

Import the decrypt function.

⚠️ IMPORTANT ⚠️

This module uses a build-time browserify transform called workerify. If you are not using browserify, you can import from the transformed version of the module by importing from the nacl-blob/dist path. e.g:

const encrypt = require('nacl-blob/dist').encrypt
const decrypt = require('nacl-blob/dist').decrypt

(Wanted, a workerify transform that writes out the contents to a separate bundle)

encrypt(key, nonce, blob, [opts], cb)

Encrypt a File or Blob, using a key and nonce. Returns an event emitter that can be used to display encryption progress. The encrypted data will be returned in the callback as a Blob.

The key must be a 32-byte Uint8Array or Node.js Buffer (see github.com/dchest/tweetnacl-js#usage for details).

The nonce must be a 16-byte Uint8Array or Node.js Buffer.

The blob must be a Blob or File.

Optional opts include:

{
  chunkSize: 1024 * 1024,
  mimeType: blob.type
}

The cb function will fire when the file/blob has been encrypted and have the the following arguments:

• err: Any error that occurred durning encryption. You should handle this.
• encryptedBlob: a Blob containing the encrypted data. This can be securely stored/transmitted along with the nonce across insecure networks and decrypted with the key (assuming secure key exchange is performed elsewhere).

Returns an Event Emitter that you can use to listen for the following events:

• progress: An event that emits the the progress of encryption in the following shape:

{
  progress, // in bytes
  length // total bytes
}

decrypt(key, nonce, encryptedBlob, [opts], [cb])

Decrypt a Blob that was encrypted using a key and nonce. Returns an event emitter that can be used to track progress. The decrypted data will be returned in the callback as a Blob.

The key must be the same 32-byte Uint8Array or Node.js Buffer used to encrypt the file. (see github.com/dchest/tweetnacl-js#usage)

The nonce must be the same 16-byte Uint8Array or Node.js Buffer used to encrypt the file.

The encryptedBlob must be an encrypted Blob or File.

Optional opts include:

{
  chunkSize: 1024 * 1024,
  mimeType: encryptedBlob.type
}

The cb function will fire when the file/blob has been decrypted and have the the following arguments:

• err: Any error that occurred durning encryption. You should handle this.
• decryptedBlob: a Blob containing the decrypted data.

Returns an Event Emitter that you can use to listen for the following events:

• progress: An event that emits the the progress of encryption in the following shape:

{
  progress, // in bytes
  length // total bytes
}

See Also

• https://github.com/jedisct1/libsodium.js
• https://github.com/jedisct1/libsodium/issues/475
• https://developer.mozilla.org/en-US/docs/Web/API/Body/blob

License

MIT