Hcaptcha

A simple Elixir package for implementing hCAPTCHA in Elixir applications.

The package is fork of the recaptcha package which uses the same flow as needed for hCaptcha. It would also be possible to integrate hCaptcha in this package but I was not able to wait for PRs to be merged so I just forked the repo.

Important Notice

The repo is works for me but is not tested that all configuration options or callbacks given by hCaptcha are processed correctly. Feel free to open PRs to resolve dependencies on the recaptcha API.

Installation

1. Add hcaptcha to your mix.exs dependencies

  defp deps do
    [
      {:hcaptcha, "~> 1.0"},
    ]
  end

1. List :hcaptcha as an application dependency

  def application do
    [ extra_applications: [:hcaptcha] ]
  end

1. Run mix do deps.get, compile

Config

By default the public and private keys are loaded via the HCAPTCHA_PUBLIC_KEY and HCAPTCHA_PRIVATE_KEY environment variables.

  config :hcaptcha,
    public_key: {:system, "HCAPTCHA_PUBLIC_KEY"},
    secret: {:system, "HCAPTCHA_PRIVATE_KEY"}

JSON Decoding

By default hCaptcha will use Jason to decode JSON responses, this can be changed as such:

  config :hcaptcha, :json_library, Poison

Usage

Render the Widget

Use raw (if you're using Phoenix.HTML) and Hcaptcha.Template.display/1 methods to render the captcha widget.

For hcaptcha with checkbox

<form name="someform" method="post" action="/somewhere">
  ...
  <%= raw Hcaptcha.Template.display %>
  ...
</form>

For invisible hcaptcha

<form name="someform" method="post" action="/somewhere">
  ...
  <%= raw Hcaptcha.Template.display(size: "invisible") %>
</form>
  ...

Since hcaptcha loads Javascript code asynchronously, you cannot immediately submit the captcha form. If you have logic that needs to know if the captcha code has already been loaded (for example disabling submit button until fully loaded), it is possible to pass in a JS-callback that will be called once the captcha has finished loading. This can be done as follows:

<form name="someform" method="post" action="/somewhere">
  ...
  <%= raw Hcaptcha.Template.display(onload: "myOnLoadCallback") %>
</form>
  ...

And then in your JS code:

function myOnLoadCallback() {
  // perform extra actions here
}

display method accepts additional options as a keyword list, the options are:

Verify API

Hcaptcha provides the verify/2 method. Below is an example using a Phoenix controller action:

  def create(conn, params) do
    case Hcaptcha.verify(params["h-aptcha-response"]) do
      {:ok, response} -> do_something
      {:error, errors} -> handle_error
    end
  end

verify method sends a POST request to the hCAPTCHA API and returns 2 possible values:

{:ok, %Hcaptcha.Response{challenge_ts: timestamp, hostname: host}} -> The captcha is valid, see the documentation for more details.

{:error, errors} -> errors contains atomised versions of the errors returned by the API, See the error documentation for more details. Errors caused by timeouts in HTTPoison or Jason encoding are also returned as atoms. If the hcaptcha request succeeds but the challenge is failed, a :challenge_failed error is returned.

verify method also accepts a keyword list as the third parameter with the following options:

Testing

In order to test your endpoints you should set the secret key to the following value in order to receive a positive result from all queries to the Hcaptcha engine.

config :hcaptcha,
  secret: "6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe"

Setting up tests without network access can be done also. When configured as such a positive or negative result can be generated locally.

config :hcaptcha,
  http_client: Hcaptcha.Http.MockClient,
  secret: "6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe"


  {:ok, _details} = Hcaptcha.verify("valid_response")

  {:error, _details} = Hcaptcha.verify("invalid_response")

Contributing

Check out CONTRIBUTING.md if you want to help.

License

MIT License.