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

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

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

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.

// 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.

$ go get github.com/tstranex/u2f

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.

• 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  SignRequest has been replaced by WebSignRequest which now includes multiple registrations.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  Challenge.RegisterRequest has been replaced by NewWebRegisterRequest.

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