webauthn

WebAuthn Library

This library is meant to handle Web Authentication for Go apps that wish to implement a multi-factor authentication, passwordless, or usernameless solution for users. This library conforms as much as possible to the guidelines and implementation procedures outlined by the relevant specifications and is conformance tested against the conformance tools.

Go Version Support Policy

This library; unless otherwise explicitly expressed; will officially support versions of go which are currently supported by the go maintainers (usually 3 minor versions) with a brief transition time (usually 1 patch release of go, for example if go 1.21.0 is released, we will likely still support go 1.17 until go 1.21.1 is released). These specific rules apply at the time of a published release.

This library in our opinion handles a critical element of security in a dependent project and we aim to avoid backwards compatibility at the cost of security wherever possible. We also consider this especially important in a language like go where their backwards compatibility when upgrading the compile tools is usually flawless.

This policy means that users who wish to build this with older versions of go may find there are features being used which are not available in that version. The current intentionally supported versions of go are as follows:

• go 1.24
• go 1.23
• go 1.22

Status

This library is still version 0, as per Semantic Versioning 2.0 rules there may be breaking changes without warning. While we strive to avoid such changes and strive to notify users they may be unavoidable.

Quickstart

go get github.com/go-webauthn/webauthn and initialize it in your application with basic configuration values.

Make sure your user model is able to handle the interface functions laid out in webauthn/types.go. This means also supporting the storage and retrieval of the credential and authenticator structs in webauthn/credential.go and webauthn/authenticator.go, respectively.

Notable Changes

The notable breaking changes made by this library are documented in the breaking changes documentation.

Documentation

The intent is to move all documentation into the go docs, and this is the location we'd recommend checking.

Examples

The examples are documented in the go docs.

Credential Record

The WebAuthn Level 3 specification describes the Credential Record which includes several required and optional elements that you should store for. See § 4 Terminology for details.

This section describes this element.

The fields listed in the specification have corresponding fields in the webauthn.Credential struct. See the below table for more information. We also include JSON mappings for those that wish to just store these values as JSON.

Flags

It's important to note that the recommendations and requirements for flag storage have changed over the course of the evolution of the WebAuthn specification. We at the present time only make the flags classified like this available for easy storage however we also make the Protocol Value available. At such a time as these recommendations or requirements change we will adapt accordingly. The Protocol Value is a raw representation of the flags and as such is resistant to breaking changes whereas the other flags or lack thereof may not be.

Implementers are therefore encouraged to use func (CredentialFlags) ProtocolValue to retrieve the raw value and webauthn.NewCredentialFlags to restore it; and instead of using the individual flags to store the value store the Protocol Value, and only store the individual flags as a means to perform compliance related decisions.

Storage

It is also important to note that restoring the webauthn.Credential with the correct values will likely affect the validity of the webauthn.Credential, i.e. if some values are not restored the webauthn.Credential may fail validation in this scenario.

Verification

As long as the webauthn.Credential struct has exactly the same values when restored the Credential Verify function can be leveraged to verify the credential against the metadata.Provider. This can be either done during registration, on every login, or with a audit schedule.

In addition to using the Credential Verify function the webauthn.Config can contain a provider which will process all registrations automatically.

At this time no tooling exists to verify the credential automatically outside the registration flow. Implementation of this is considered domain logic and beyond the scope of what we provide documentation for; we just provide the necessary tooling to implement this yourself.

Acknowledgements

We graciously acknowledge the original authors of this library github.com/duo-labs/webauthn for their amazing implementation. In particular we'd like to acknowledge Nick Steele who not only created the original library, but maintained it, and has been an active member of the WebAuthn Working Group quite some time. Without their amazing work this library could not exist.