# Go FIDO U2F Library

This Go package implements the parts of the FIDO U2F specification required on
the server side of an application.

[![Build Status](https://travis-ci.org/tstranex/u2f.svg?branch=master)](https://travis-ci.org/tstranex/u2f)

## Features

- Native Go implementation
- No dependancies other than the Go standard library
- Token attestation certificate verification

## Usage

Please visit http://godoc.org/github.com/tstranex/u2f for the full
documentation.

### How to enrol a new token

```go
app_id := "http://localhost"

// Send registration request to the browser.
c, _ := NewChallenge(app_id, []string{app_id})
req, _ := c.RegisterRequest()

// Read response from the browser.
var resp RegisterResponse
reg, err := Register(resp, c, nil)
if err != nil {
    // Registration failed.
}

// Store registration in the database.
```

### How to perform an authentication

```go
// Fetch registration and counter from the database.
var reg Registration
var counter uint32

// Send authentication request to the browser.
c, _ := NewChallenge(app_id, []string{app_id})
req, _ := c.SignRequest(reg)

// Read response from the browser.
var resp SignResponse
newCounter, err := reg.Authenticate(resp, c, counter)
if err != nil {
    // Authentication failed.
}

// Store updated counter in the database.
```

## Installation

```
$ go get github.com/tstranex/u2f
```

## Example

See u2fdemo/main.go for an full example server. To run it:

```
$ go install github.com/tstranex/u2f/u2fdemo
$ ./bin/u2fdemo
```

Open https://localhost:3483 in Chrome.
Ignore the SSL warning (due to the self-signed certificate for localhost).
You can then test registering and authenticating using your token.

## Changelog

- 2016-12-18: The package has been updated to work with the new
  U2F Javascript 1.1 API specification. This causes some breaking changes.

  `SignRequest` has been replaced by `WebSignRequest` which now includes
  multiple registrations. This is useful when the user has multiple devices
  registered since you can now authenticate against any of them with a single
  request.

  `WebRegisterRequest` has been introduced, which should generally be used
  instead of using `RegisterRequest` directly. It includes the list of existing
  registrations with the new registration request. If the user's device already
  matches one of the existing registrations, it will refuse to re-register.

  `Challenge.RegisterRequest` has been replaced by `NewWebRegisterRequest`.

## License

The Go FIDO U2F Library is licensed under the MIT License.