I would like to ask if is still impossible, using JavaScript, to get key from USB token or from certificate stored in Browser. I was reading many articles which said WebCryptoApi doesn't enable to do that.
Is any option to get key from token? Maybe something was changed?
It is not possible for now. The WebCryptoApi does not support using keys stored in external keystores like smartcards, Mozilla keystore or Windows KeyStore (used by Chrome and Explorer), and reading the comments of the last conferences, it is not a current priority.
There is another Javascript API specification of W3C to be used with Web Cryptography Api. See WebCrypto Key Discovery
This note describes a JavaScript API for discovering named, origin-specific pre-provisioned cryptographic keys for use with the Web Cryptography API.
Unfortunately is still a working group under development.
I think that with the Chrome Native Messaging implementations its possible. The native messaging implemented into Firefox and Edge too. Check this: https://github.com/open-eid/chrome-token-signing
来源：https://stackoverflow.com/questions/38605661/javascript-key-certificate-from-usb-token