lib/amazon_flex_pay/api.rb
def verify_request(request)
      verify_signature(
        # url without query string
        request.protocol + request.host_with_port + request.path,
        # raw parameters
        request.get? ? request.query_string : request.raw_post
      )
    end
def verify_request(request)
      verify_signature(
        # url without query string
        request.protocol + request.host_with_port + request.path,
        # raw parameters
        request.get? ? request.query_string : request.raw_post
      )
    end
This is how you verify IPNs and pipeline responses.
 Pass the entire request object.