# Secure and Efficient Authentication Scheme in IoT Environments
## 2 Background and Related Works
### Problem Definition  
As mentioned in Section 2.1, existing schemes have high computation, communication, or storage costs, despite the fact that the IoT devices and sensors are in limited environments (e.g., low memory, low power, network confinement). Therefore, current methods suffer from the following problems:  
* High response time: In IoT network communication, high computing operation is performed in limited-capacity IoT devices, where high communication bit message exchanges happen between node devices, which considerably increase the response time of the message in communication ([PERSON] et al., 2019).
* High computational overhead: Due to high computation cost, the limited-capacity IoT devices need to process mutual authentication and session key agreement requests using limited memory. In addition, in the real-time scenario of processing a high (i.e., millions or zillions) number of authentication requests between IoT devices, it consumes high processing power, which is limited in IoT devices, making IoT devices suffer from high computational overheads ([PERSON] et al., 2019).
* Excess memory consumption: The high computational cost of recent schemes causes limited-capacity IoT devices to perform a high level of processing and operations using limited memory, strongly impacting lower down device efficiency and performance (i.e., IoT device processors require considerably increased execution time to execute large content in memory) to a certain extent ([PERSON] et al., 2019).
* Excess electricity power consumption: The level of computing power consumption is directly proportional to electrical power consumption. The recent schemes make limited-capacity IoT devices suffer from high computational overheads, resulting in high electrical power consumption ([PERSON] et al., 2019).
* Lack of service availability: Due to the high running cost, it is a burden to handle and process millions or zillions of authentication and communication requests in real-time; this creates a considerable time delay for service in IoT systems ([PERSON] et al., 2019).
* Lack of performance and costly solutions: Due to high running costs, IoT devices suffer computationally because of their limited processing and storage capacities. When handling a high (e.g., millions or zillions) number of authentication requests in a huge IoT network, this affects their performance and increases the possibility of damage to IoT devices, including additional charges for replacement and maintenance [39].  
Thus, the currently existing works lack a robust authentication model to ensure the low energy utilization of cryptographic operations, which results in usability issues and strongly impacts the avoidance of the adaption of existing authentication technology in real IoT cloud scenarios. While developing a reliable and secure IoT device, not only privacy and security but also lightweight and efficient mechanisms are the major concerns. In this sense, much work has been done. Nevertheless, existing schemes either have high computation, storage, or communication costs or fail to address many of the security attributes, which results in the existing works failing to address usability problems. Thus, none of them meet the requirement of a lightweight security design. To address all those contexts, we propose a novel lightweight and secure authentication scheme in this research.