Are you expecting people to disclose their passphrase to a third party ?
The idea is probably not so bad but the browser is really not the place to run these kind of experiments.
The idea is probably not so bad but the browser is really not the place to run these kind of experiments.
You download basically a few bloom filters for low-entropy 1-grams, 2-grams, and 3-grams, and there's some highly optimized Javascript to do probabilistic matches.
No personal offense intended, that is a genuine problem with your approach.
Once you've loaded all the 3-grams (~50MB of data), you can run entirely offline, close the page, and then go back online.
Then try your password.
Alternate solution: load the web page and then turn off your WiFi while you test it.