# File lib/openid/server.rb, line 300
      def answer(assoc)
        response = OpenIDResponse.new(self)

        fields = {
          'expires_in' => assoc.expires_in.to_s,
          'assoc_type' => 'HMAC-SHA1',
          'assoc_handle' => assoc.handle
        }

        # add the session specific arguments to the response fields
        response.fields.update(fields)        
        response.fields.update(@session.answer(assoc.secret))
        
        if @session.session_type != 'plaintext'
          response.fields['session_type'] = @session.session_type
        end

        return response
      end