gistfile1.rb

class ActionController::Base
  def self.check_signatures(key, *args)
    before_filter lambda { check_signature(key)}, *args
  end

  def self.check_signature(key)
    raise InvalidWebhookSignature
  end
end

class Webhooks::TestController < ApplicationController

  check_signatures "abc123"

  def index
  end

end