webauthn : Web Authentication API in Go

Overview

This project provides a low-level and a high-level API to use the Web Authentication API (WebAuthn).

Demo

Install

go get github.com/koesie10/webauthn

Attestation

By default, this library does not support any attestation statement formats. To use the default attestation formats, you will need to import github.com/koesie10/webauthn/attestation or any of its subpackages if you would just like to support some attestation statement formats.

Please note that the Android SafetyNet attestation statement format depends on gopkg.in/square/go-jose.v2, which means that this package will be imported when you import either github.com/koesie10/webauthn/attestation or github.com/koesie10/webauthn/attestation/androidsafetynet.

High-level API

The high-level API can be used with the net/http package and simplifies the low-level API. It is located in the webauthn subpackage. It is intended for use with e.g. fetch or XMLHttpRequest JavaScript clients.

First, make sure your user entity implements User. Then, create a new entity implements Authenticator that stores each authenticator the user registers.

Then, either make your existing repository implement AuthenticatorStore or create a new repository.

Finally, you can create the main WebAuthn struct supplying the Config options:

w, err := webauthn.New(&webauthn.Config{
    // A human-readable identifier for the relying party (i.e. your app), intended only for display.
    RelyingPartyName:   "webauthn-demo",
    // Storage for the authenticator.
    AuthenticatorStore: storage,
})		

Then, you can use the methods defined, such as StartRegistration to handle registration and login. Every handler requires a Session, which stores intermediate registration/login data. If you use gorilla/sessions, use webauthn.WrapMap(session.Values). Read the documentation for complete information on what parameters need to be passed and what values are returned.

For example, a handler for finishing the registration might look like this:

func (r *http.Request, rw http.ResponseWriter) {
    ctx := r.Context()

    // Get the user in some way, in this case from the context
    user, ok := UserFromContext(ctx)
    if !ok {
        rw.WriteHeader(http.StatusForbidden)
        return
    }

    // Get or create a session in some way, in this case from the context
    sess := SessionFromContext(ctx)

    // Then call FinishRegistration to register the authenticator to the user
    h.webauthn.FinishRegistration(r, rw, user, webauthn.WrapMap(sess))
}

A complete demo application using the high-level API which implements all of these interfaces and stores data in memory is available here.

JavaScript examples

This class is an example that can be used to handle the registration and login phases. It can be used as follows:

const w = new WebAuthn();

// Registration
w.register().then(() => {
    alert('This authenticator has been registered.');
}).catch(err => {
    console.error(err);
    alert('Failed to register: ' + err);
});

// Login
w.login().then(() => {
    alert('You have been logged in.');
}).catch(err => {
    console.error(err);
    alert('Failed to login: ' + err);
});

Or, with latest async/await paradigm:

const w = new WebAuthn();

// Registration
try {
    await w.register();
    alert('This authenticator has been registered.');
} catch (err) {
    console.error(err)
    alert('Failed to register: ' + err);
}

// Login
try {
    await w.login();
    alert('You have been logged in.');
} catch(err) {
    console.error(err);
    alert('Failed to login: ' + err);
}

Low-level API

The low-level closely resembles the specification and the high-level API should be preferred. However, if you would like to use the low-level API, the main entry points are:

• ParseAttestationResponse
• IsValidAttestation
• ParseAssertionResponse
• IsValidAssertion

License

MIT.