reCAPTCHA Authenticator

This is a sample Authenticator plug-in for the Curity Identity Server.

It demonstrates how to build a simple plugin that can be used to authenticate via Google's reCAPTCHA v2. Please note that this should only be used combined with another authenticator such as the HTML form authenticator, as the reCAPTCHA alone does not provide a subject (i.e. a user) but merely confirms whether the form was submitted by a human.