Bug: lightwallet.keystore.createVault and vault.keyFromPassword very slow

[Tschuck]

Hi,

We use lightwallet 3.0.1 in our progressive web application. In some cases, the two functions

• lightwallet.keystore.createVault
• vault.keyFromPassword

take an incredibly long time to deliver a result. On a desktop browser, maximum peaks of 3s - 5s can be detected. On mobile devices, be it Chrome / Safari IOS or Chrome Android, times of up to 40 - 80s can be recorded.

After a page reload, this seems to worsen.
Within Angular 5 and Ionic 3 on an IOS device, the behavior deteriorates after each side reload within the application. After reloading the page 5 - 10 times and creating new vaults, the IOS device stops the application completely and restarts the app.

After some debugging i think it could be a problem with the following lines within the keystore.js file.

• Line: 86 - 89

var hdRoot = new Mnemonic(mnemonic).toHDPrivateKey().xprivkey;
var hdRootKey = new bitcore.HDPrivateKey(hdRoot);
var hdPathKey = hdRootKey.derive(hdPathString).xprivkey;
this.encHdRootPriv = encryptString(hdPathKey, pwDerivedKey);

• Line: 355

scrypt(password, salt, logN, r, dkLen, interruptStep, cb, null);

Here's a fiddle-JS to investigate the problem. Please test on mobile devices, there the problem can be simulated better. A qr-code to scan it directly on your mobile device is attached too.
For single testing of createVault, comment out lines 43 - 45.

https://jsfiddle.net/654b5yez

Here some images of our tests on several devices:

• Desktop Chrome
  

• Desktop Firefox
  

• Nexus 5X Android Chrome
  

• IPAD Air IOS Safari
  

Thank you for your support in advance. Notify me, if i can help you.

[Tschuck]

Its a problem with the scrypt-async-js library. We have created a pull request to handle the issue scrypt-async-js pull request.

[Tschuck]

Its not a problem with the scrypt-async-js library itself, its a problem the configuration of this library. By using an interruptStep of 200, to many setTimeouts are used.

I tested around a bit and a value of 1000 - 2000 should improve the behavior significantly.