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npm install fido2-lib


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 fido2-server-demo and / or webauthn.org


  • 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-lib");

// 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.attestationResult(clientAssertionResponse, assertionExpectations); // will throw on error

// authentication complete!

For a real-life example, refer to component-fido2.


Note that while I used to be Technical Director for FIDO Alliance (and I am currently the Technical Advisor for FIDO Alliance), THIS PROJECT IS NOT ENDORSED OR SPONSORED BY FIDO ALLIANCE.

Work for this project is supported by my consulting company: WebAuthn Consulting.

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