The increasing proliferation of the Internet of Things devices requires ever new cryptographic protocols. The reason is that these devices often operate with limited computing and energy resources. Consequently, the desired solutions must meet such requirements, which is why they are referred to as lightweight protocols. However, it is still a challenge to define a common understanding of what a lightweight protocol really is, how to measure it effectively or how to provide some standardized basis. This paper will therefore address the current situation and based on an analysis, it will present a novel method, a metric that can be used in such cases. In other words, considering solutions for IoT devices, the problem remains how to provide a de facto standardized assessment of the efficiency of cryptographic protocols, i.e. an appropriate metric, which can serve as a common denominator, which is needed for further advances in this area.