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https://github.com/go-webauthn/webauthn

Webauthn/FIDO2 library in golang
https://github.com/go-webauthn/webauthn

ctap2 fido2 go golang passwordless passwordless-authentication security webauthn

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Webauthn/FIDO2 library in golang

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README 

        
# WebAuthn Library



[![GoDoc](https://godoc.org/github.com/go-webauthn/webauthn?status.svg)](https://godoc.org/github.com/go-webauthn/webauthn)

[![Go Report Card](https://goreportcard.com/badge/github.com/go-webauthn/webauthn)](https://goreportcard.com/report/github.com/go-webauthn/webauthn)



This library is meant to handle [Web Authentication](https://www.w3.org/TR/webauthn) for Go apps that wish to implement 

a passwordless solution for users. This library conforms as much as possible to the guidelines and implementation

procedures outlined by the document.



## Fork



This library is a hard fork of [github.com/duo-labs/webauthn] and is the natural successor to that library.



See the [migration](MIGRATION.md) guide for more information about how to migrate and the differences between the

libraries.



It is distributed under the same 3-Clause BSD license as the original fork, with the only amendment being the additional

3-Clause BSD license attributing license rights to this repository.



## 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 1.22

- go 1.21

- ~~go 1.20~~:

  - Go 1.20 support has been removed due to the new toolchain directive and lack of support in Go 1.20. This directive

    is unfortunately being used in dependent libraries and we'd opt for ensuring we can easily obtain potential fixes

    to CVE's rather than backwards compatibility. A such we have lifted the version requirement and implemented the

    toolchain directive in our module to reflect the intended toolchain.



## 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.



## Examples



The following examples show some basic use cases of the library. For consistency sake the following variables are used

to denote specific things:



- Variable `webAuthn`: the `webauthn.WebAuthn` instance you initialize elsewhere in your code

- Variable `datastore`: the pseudocode backend service that stores your webauthn session data and users such as PostgreSQL 

- Variable `session`: the webauthn.SessionData object

- Variable `user`: your webauthn.User implementation



We try to avoid using specific external libraries (excluding stdlib) where possible, and you'll need to adapt these

examples with this in mind.



### Initialize the request handler



```go

package example



import (

	"fmt"



	"github.com/go-webauthn/webauthn/webauthn"

)



var (

	webAuthn *webauthn.WebAuthn

	err error

)



// Your initialization function

func main() {

	wconfig := &webauthn.Config{

		RPDisplayName: "Go Webauthn", // Display Name for your site

		RPID: "go-webauthn.local", // Generally the FQDN for your site

		RPOrigins: []string{"https://login.go-webauthn.local"}, // The origin URLs allowed for WebAuthn requests

	}

	

	if webAuthn, err = webauthn.New(wconfig); err != nil {

		fmt.Println(err)

	}

}

```



### Registering an account



```go

package example



func BeginRegistration(w http.ResponseWriter, r *http.Request) {

	user := datastore.GetUser() // Find or create the new user  

	options, session, err := webAuthn.BeginRegistration(user)

	// handle errors if present

	// store the sessionData values 

	JSONResponse(w, options, http.StatusOK) // return the options generated

	// options.publicKey contain our registration options

}



func FinishRegistration(w http.ResponseWriter, r *http.Request) {

	user := datastore.GetUser() // Get the user

	

	// Get the session data stored from the function above

	session := datastore.GetSession()

		

	credential, err := webAuthn.FinishRegistration(user, session, r)

	if err != nil {

		// Handle Error and return.



		return

	}

	

	// If creation was successful, store the credential object

	// Pseudocode to add the user credential.

	user.AddCredential(credential)

	datastore.SaveUser(user)



	JSONResponse(w, "Registration Success", http.StatusOK) // Handle next steps

}

```



### Logging into an account



```go

package example



func BeginLogin(w http.ResponseWriter, r *http.Request) {

	user := datastore.GetUser() // Find the user

	

	options, session, err := webAuthn.BeginLogin(user)

	if err != nil {

		// Handle Error and return.



		return

	}

	

	// store the session values

	datastore.SaveSession(session)

	

	JSONResponse(w, options, http.StatusOK) // return the options generated

	// options.publicKey contain our registration options

}



func FinishLogin(w http.ResponseWriter, r *http.Request) {

	user := datastore.GetUser() // Get the user 

	

	// Get the session data stored from the function above

	session := datastore.GetSession()

	

	credential, err := webAuthn.FinishLogin(user, session, r)

	if err != nil {

		// Handle Error and return.



		return

	}



	// Handle credential.Authenticator.CloneWarning



	// If login was successful, update the credential object

	// Pseudocode to update the user credential.

	user.UpdateCredential(credential)

	datastore.SaveUser(user)

	

	JSONResponse(w, "Login Success", http.StatusOK)

}

```



## Modifying Credential Options



You can modify the default credential creation options for registration and login by providing optional structs to the 

`BeginRegistration` and `BeginLogin` functions. 



### Registration modifiers



You can modify the registration options in the following ways:



```go

package example



import (

	"github.com/go-webauthn/webauthn/protocol"

	"github.com/go-webauthn/webauthn/webauthn"

)



var webAuthn webauthn.WebAuthn // init this in your init function



func beginRegistration() {

	// Updating the AuthenticatorSelection options. 

	// See the struct declarations for values

	authSelect := protocol.AuthenticatorSelection{

		AuthenticatorAttachment: protocol.AuthenticatorAttachment("platform"),

		RequireResidentKey: protocol.ResidentKeyNotRequired(),

		UserVerification: protocol.VerificationRequired,

	}



	// Updating the ConveyencePreference options. 

	// See the struct declarations for values

	conveyancePref := protocol.PreferNoAttestation



	user := datastore.GetUser() // Get the user  

	opts, session, err := webAuthn.BeginRegistration(user, webauthn.WithAuthenticatorSelection(authSelect), webauthn.WithConveyancePreference(conveyancePref))



	// Handle next steps

}

```



### Login modifiers



You can modify the login options to allow only certain credentials:



```go

package example



import (

	"github.com/go-webauthn/webauthn/protocol"

	"github.com/go-webauthn/webauthn/webauthn"

)



var webAuthn webauthn.WebAuthn // init this in your init function



func beginLogin() {

	// Updating the AuthenticatorSelection options. 

	// See the struct declarations for values

	allowList := make([]protocol.CredentialDescriptor, 1)

	allowList[0] = protocol.CredentialDescriptor{

		CredentialID: credentialToAllowID,

		Type: protocol.CredentialType("public-key"),

	}



	user := datastore.GetUser() // Get the user  



	opts, session, err := w.BeginLogin(user, webauthn.WithAllowedCredentials(allowList))



	// Handle next steps

}

```



## Timeout Mechanics



The library by default does not enforce timeouts. However the default timeouts sent to the browser are taken from the

specification. You can override both of these behaviours however.



```go

package example



import (

	"fmt"

	"time"

	

	"github.com/go-webauthn/webauthn/protocol"

	"github.com/go-webauthn/webauthn/webauthn"

)



func main() {

	wconfig := &webauthn.Config{

		RPDisplayName: "Go Webauthn",                               // Display Name for your site

		RPID:          "go-webauthn.local",                         // Generally the FQDN for your site

		RPOrigins:     []string{"https://login.go-webauthn.local"}, // The origin URLs allowed for WebAuthn requests

		Timeouts: webauthn.TimeoutsConfig{

			Login: webauthn.TimeoutConfig{

				Enforce:    true, // Require the response from the client comes before the end of the timeout.

				Timeout:    time.Second * 60, // Standard timeout for login sessions.

				TimeoutUVD: time.Second * 60, // Timeout for login sessions which have user verification set to discouraged.

			},

			Registration: webauthn.TimeoutConfig{

				Enforce:    true, // Require the response from the client comes before the end of the timeout.

				Timeout:    time.Second * 60, // Standard timeout for registration sessions.

				TimeoutUVD: time.Second * 60, // Timeout for login sessions which have user verification set to discouraged.

			},

		},

	}

	

	webAuthn, err := webauthn.New(wconfig)

	if err != nil {

		fmt.Println(err)

	}

}

```



## 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](https://www.w3.org/TR/webauthn-3/#credential-record) 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.



|    Specification Field    |       Library Field        |         JSON Field         |                                           Notes                                           |

|:-------------------------:|:--------------------------:|:--------------------------:|:-----------------------------------------------------------------------------------------:|

|           type            |            N/A             |            N/A             |                       This field is always `publicKey` for WebAuthn                       |

|            id             |             ID             |             id             |                                                                                           |

|         publicKey         |         PublicKey          |         publicKey          |                                                                                           |

|         signCount         |  Authenticator.SignCount   |  authenticator.signCount   |                                                                                           |

|        transports         |         Transport          |         transport          |                                                                                           |

|       uvInitialized       |     Flags.UserVerified     |     flags.userVerified     |                                                                                           |

|      backupEligible       |    Flags.BackupEligible    |    flags.backupEligible    |                                                                                           |

|        backupState        |     Flags.BackupState      |     flags.backupState      |                                                                                           |

|     attestationObject     |     Attestation.Object     |     attestation.object     | This field is a composite of the attestationObject and the relevant values to validate it |

| attestationClientDataJSON | Attestation.ClientDataJSON | attestation.clientDataJSON |                                                                                           |



### 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](https://pkg.go.dev/github.com/go-webauthn/webauthn/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. Without their amazing work this library could not exist.



[github.com/duo-labs/webauthn]: https://github.com/duo-labs/webauthn

[webauthn.Credential]: https://pkg.go.dev/github.com/go-webauthn/webauthn/webauthn#Credential

[metadata.Provider]: https://pkg.go.dev/github.com/go-webauthn/webauthn/metadata#Provider

[Credential Verify]: https://pkg.go.dev/github.com/go-webauthn/webauthn/webauthn#Credential.Verify