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2.5.0 • Public • Published

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npm install fido2-library

npm version


A library for performing FIDO 2.0 / WebAuthn server functionality

This library contains all the functionality necessary for implementing a full FIDO2 / WebAuthn server. It intentionally does not implement any kind of networking protocol (e.g. - REST endpoints) so that it can remain independent of any messaging protocols.

There are four primary functions:

  1. attestationOptions - creates the challenge that will be sent to the client (e.g. - browser) for the credential create call. Note that the library does not keep track of sessions or context, so the caller is expected to associate the resulting challenge with a session so that it can be appropriately matched with a response.
  2. attestationResult - parses and validates the response from the client
  3. assertionOptions - creates the challenge that will be sent to the client for credential assertion.
  4. assertionResult - parses and validates the response from the client

There is also an extension point for adding new attestation formats.

Full documentation can be found here.

For working examples see OWASP Single Sign-On and / or webauthn.io


  • Works with Windows Hello
  • Attestation formats: packed, tpm, android-safetynet, fido-u2f, none
  • Convenient API for adding more attestation formats
  • Convenient API for adding extensions
  • Metadata service (MDS) support enables authenticator root of trust and authenticator metadata
  • Support for multiple simultaneous metadata services (e.g. FIDO MDS 1 & 2)
  • Crypto families: ECDSA, RSA
  • x509 cert parsing, support for FIDO-related extensions, and NIST Public Key Interoperability Test Suite (PKITS) chain validation (from pki.js)
  • Returns parsed and validated data, along with extra audit data for risk engines


Instantiate Library (Simple):

const { Fido2Lib } = require("fido2-library");
// create a new instance of the library
var f2l = new Fido2Lib();

Instantiate Library (Complex):

// could also use one or more of the options below,
// which just makes the options calls easier later on:
var f2l = new Fido2Lib({
    timeout: 42,
    rpId: "example.com",
    rpName: "ACME",
    rpIcon: "https://example.com/logo.png",
    challengeSize: 128,
    attestation: "none",
    cryptoParams: [-7, -257],
    authenticatorAttachment: "platform",
    authenticatorRequireResidentKey: false,
    authenticatorUserVerification: "required"


var registrationOptions = await f2l.attestationOptions();
// make sure to add registrationOptions.user.id
// save the challenge in the session information...
// send registrationOptions to client and pass them in to `navigator.credentials.create()`...
// get response back from client (clientAttestationResponse)
var attestationExpectations = {
    challenge: "33EHav-jZ1v9qwH783aU-j0ARx6r5o-YHh-wd7C6jPbd7Wh6ytbIZosIIACehwf9-s6hXhySHO-HHUjEwZS29w",
    origin: "https://localhost:8443",
    factor: "either"
var regResult = await f2l.attestationResult(clientAttestationResponse, attestationExpectations); // will throw on error
// registration complete!
// save publicKey and counter from regResult to user's info for future authentication calls


var authnOptions = await f2l.assertionOptions();
// save the challenge in the session information...
// send authnOptions to client and pass them in to `navigator.credentials.get()`...
// get response back from client (clientAssertionResponse)
var assertionExpectations = {
    challenge: "eaTyUNnyPDDdK8SNEgTEUvz1Q8dylkjjTimYd5X7QAo-F8_Z1lsJi3BilUpFZHkICNDWY8r9ivnTgW7-XZC3qQ",
    origin: "https://localhost:8443",
    factor: "either",
    publicKey: "-----BEGIN PUBLIC KEY-----\n" +
        "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAERez9aO2wBAWO54MuGbEqSdWahSnG\n" +
        "MAg35BCNkaE3j8Q+O/ZhhKqTeIKm7El70EG6ejt4sg1ZaoQ5ELg8k3ywTg==\n" +
        "-----END PUBLIC KEY-----\n",
    prevCounter: 362
var authnResult = await f2l.assertionResult(clientAssertionResponse, assertionExpectations); // will throw on error
// authentication complete!

For a real-life example, refer to OWASP Single Sign-On.


Work for this project was supported by Adam Power.


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