# File lib/httpclient/auth.rb, line 294
    def get(req)
      target_uri = req.header.request_uri
      param = Util.hash_find_value(@challenge) { |uri, v|
        Util.uri_part_of(target_uri, uri)
      }
      return nil unless param
      user, passwd = Util.hash_find_value(@auth) { |uri, auth_data|
        Util.uri_part_of(target_uri, uri)
      }
      return nil unless user
      uri = req.header.request_uri
      calc_cred(req.header.request_method, uri, user, passwd, param)
    end