def application do
    [
      # ...
      applications: [:phoenix, :cowboy, :logger, :exrecaptcha]
      # ...
    ]
  end
  defp deps do
    [
      {:phoenix, "0.5.0"},
      {:cowboy, "~> 1.0.0"},
      #...
      {:ibrowse, github: "cmullaparthi/ibrowse", tag: "v4.1.0"},
      {:exrecaptcha, "~> 0.0.3"}
    ]
  end

config :exrecaptcha,
  api_config: %{ verify_url: "https://www.google.com/recaptcha/api/verify",
                 public_key: "YOUR_PUBLIC_KEY",
                 private_key: "YOUR_PRIVATE_KEY" }

# your post method should route you here:
def create(conn, params) do
  # do stuff, then check for the validity of the captcha
  :ok = verify_captcha(conn, params)
end
defp verify_captcha(conn, %{"recaptcha_challenge_field" => challenge,
                            "recaptcha_response_field" => response}) do
  remote_ip = conn.remote_ip
  Exrecaptcha.verify(remote_ip, challenge, response)
end