Nowadays, emerging trends in the field of technology related to big data, cognitive computing, and the Internet of Things (IoT) have become closely related to people's lives. One of the hottest areas these days is transforming traditional cities into smart cities, using the concept of IoT depending on several types of modern technologies to develop and manage cities in order to improve and facilitate the quality of life. The Internet of Things networks consist of a huge number of interconnected devices and sensors that process and transmit data. Such Activities require efficient energy to be performed at the highest quality and range, hence the concept of Long-Range Wide Area Network (LoRaWAN) introduced, which concerns about delivering lower energy consumption, supporting large networks and mobility. In this paper, the security mechanisms in LoRaWAN will be evaluated by literature review from many authors. The expected outcomes are to study and evaluate the LoRaWAN mechanism and class and protocol stacks.