# An Enhanced Lightweight IoT-based Authentication Scheme in Cloud Computing Circumstances
## 1 Introduction  
Information technology has grown rapidly in the past few years, mainly developing new technologies focused on how to take advantage of the Internet. In this sense, innovations such as wireless access, high speed connection, APIs and electronic services have successfully entered the Internet arena. At the same time, researchers and computer professionals have developed new communication technologies, such as Wi-Fi, 4G, 5G, routing protocols, LTE, Bluetooth, RFID, among others, which offer broader ranges to users. In parallel, the cost of technology keeps decreasing, year by year, making Internet connectivity more accessible for everyone through smaller devices as tablets and smartphones. On the other hand, as the Internet has become ubiquitous, faster, and increasingly accessible to non-technical communities, social networking and collaborative services, emerging technologies such as artificial intelligence, big data, cloud computing, wireless sensor networks and the Internet of Things (IoT) have appeared, enabling people to communicate and share interests in many more ways. As a consequence, these novel technologies are changing the world, again, creating new business opportunities, new applications to enhance safety, comfort, and efficiency reducing human efforts, and new ways to collect and analyse data. Among these five emerging technologies, the IoT and cloud computing have become more and more relevant to academia and industry. In 1999 [PERSON] introduced the concept of IoT [1], which is defined as the connection of physical objects (devices/sensors) through the Internet [2]. Cloud computing, on the other hand, was introduced in 1961 by [PERSON] [3], and 36 years later, [PERSON] explained the concept in the scenario of current technology era [4], defined as a large-scale distributed computing paradigm which drives the economy of many companies based on virtualization, managed computing power, and storage focused on its core business [3]. The IoT applications are classified into the following categories [5; 6]: (a) Internet of sensors (IoS), which is a network made up of sensors which collect and transmit a types of data; (b) Internet of energy (IoE), which is a network of smart grids to analyse and control the energy production, consumption, storage, and distribution; (c) machine to machine (M2M) communication is a network of devices/sensors connected through the Internet; and (d) Internet of Vehicles (IoV), which is a network of vehicles that can share information about the state of the road. Another classification is based on the communication models [7]: (a) machine-to-machine communication, which includes multiple devices/sensors connected to exchange data among them without a physical infrastructure; (b) machine-to-cloud communication, which includes devices/sensors that consume services from a cloud server for storing and processing data; and (c) machine-to-gateway communication, which includes devices/sensors that collaborate as a proxy to expand the range of the network. In the case of cloud computing, we can find four types of deployment models offered by cloud providers. The first type is known as public cloud, where services and systems are available for anyone through an open communication channel. The second type is known as private cloud where services and systems are accessible for certain users/employees or organizations through a secure communication channel. The third type is known as community cloud where the cloud is shared by several organizations. The last type which includes a public and private cloud to share resources is known as hybrid cloud [4]. From these service platforms, cloud computing allows the interconnection of everything around us, including our vital signs, personal and sensitive data, that travel through an open communication channel to different sites [8; 9; 10]. This is possible because devices/sensors automatically collect a huge amount of data and stores them on cloud servers [11; 12; 13; 14].