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What is this?

We all use Chrome everyday, and yet we just discovered that Chrome extensions can be given permission to connect to your USB devices! Once we heard this, we had to make this extension that communicates with Opendime over USB.

This extension can:

  • load the random numbers (256k bytes) to initialize new Opendimes
  • read the bitcoin payment address, and link to public block explorers
  • perform an in-depth verification of the Opendime, including:
    • bitcoin messages signature (using a unique nonce each time)
    • factory certificate verification
    • verification by signed message (with nonce) to the anti-counterfieting chip
  • be easy to use

Once installed, all of the above is done just by plugging in an Opendime!

How to Install

Go to the Chrome Web Store, and click Add Extension, and you're done!

Get the Opendime App here

Problem: Chrome no longer supports extensions on any OS other than ChromeOS. See notes below.

Screen Shot

Opendime App screen shot

Web References

Submodules / Components used

Useful Chrome internal links

  • chrome://extensions keep open all the dev time
  • chrome://device-log lists USB events!

For HTML and Front End Devs

  • look at the end of code.js for some things that can be commented one way or the other; you can make it display test data for most cases
  • App window is currently coded to be 840x640px but we can change that. You should work in a similarly-sized window.
  • simply load main.html into chrome from the filesystem, and most things work:
open main.html

Debug As Extension.

To debug/change it as an extension, go to chrome://extensions/ and...

  • click "Developer mode"
  • click "Load unpacked extension"
  • give it this directory (ie. where manifest.json is located)
  • Use the Launch and/or Reload buttons
  • once installed, will also pop up any time an opendime is inserted

Life Cycle

Chrome "apps" are deprecated and going away. However, "extensions" do not support USB, so we are an "app" today. Still, it's listed under 'extensions' in all Chrome UI (present version), but since we are an "app", the contents of manifest.json is quite limited.

Also the top of every page in the google docs, they warn us:

Important: Chrome will be removing support for Chrome Apps on Windows, Mac, and Linux. Chrome OS will continue to support Chrome Apps. Additionally, Chrome and the Web Store will continue to support extensions on all platforms. Read the announcement and learn more about migrating your app.

Timeline for app non-support is 2018, and WebUSB won't be ready for years. Let's just take it one day at a time.


This app works well with NW.js without any changes. Going forward, a few changes would fix URL opening and improve the native menus and such.

To try it with NW.js, first download NW.js for your platform. Then run the executable (NW.exe or nwjs) from inside this directory with . (just dot) as the first argument.


Chrome browser extension (app) to easily use Opendime hardware wallet from your desktop!







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