Wireless Sensor Network (WSN) is used to enhance and automate the information capturing capabilities of critical projects such as Medical Monitoring, Scientific Experiments and Research, Industries, Factories, Transportation, etc. Wearable devices, Smart Cities, Smart Agriculture, Virtual Reality (VR), Augmented Reality (AR) gaming are some of its newer applications. Governments also use WSN to gather data for their military applications. WSN nodes have gained this massive adoption because they are cheap, modular, programmable, ad-hoc configurable, can operate in an open environment, wirelessly connected, etc. These features also make WSN easy to attack. Data captured by WSN are private or sensitive for individuals or organizations. Hence, security is one of the essential issues of research of WSN. In this paper, we present a current brief review of WSN Security. First, WSN and its architecture is introduced. Then, a layer-wise classification of security attacks and possible mitigation techniques are discussed to understand attacks and their severity. To secure WSN, lightweight cryptographic algorithms are analyzed for their suitability, performance, battery requirements, etc.
Wireless Sensor Network (WSN) has a decade's old origin . Like any computer technology, the origin of WSN is attributed to military requirements and heavy industrial applications. The history of WSN is much older than the Internet and even from most generations of computers. The first system that can mimic modern WSN was Sound Surveillance System (SOSUS)  developed in the 1950s by US Military. SOSUS was used to track and detect Soviet submarines. Further, with the establishment of the Defence Advanced Research Projects Agency (DARPA) project by the US Govt. Distributed Sensor Network (DSN) program was formally started in 1980. After its formal introduction, research interests started to rise and people from academics and research labs showed huge interest. Later DSN was modified into modern WSN. WSN in the most basic term, is a network of sensors spread over small or large geographical areas that are used to sense and collect any type of physical or environmental quantity like heat, temperature, light, sound, moisture, suspended particle matter etc.. The data collected via these sensors are transmitted to a central device, which acts as a sink. Central device or sink further transmit these data to its destination over the network. Sensors are cheap and easy to install, leading to WSN's huge adoption in its early years. Sensors communicate with each other using radio waves. Most WSN networks are Ad-Hoc networks in which sensors are scattered over the particular geographical area, and the nodes are self-configured such that they communicate with each other and determine the best path to reach the sink by themselves using strategies like lowest node count to sink, a path with high battery power, a path with powerful nodes etc. A WSN node comprises of central processing unit, a communication unit, a sensing unit, and a power unit. Nodes are low-powered (battery or energysource), low-power computation devices whose only purpose is to sense and collect data and transmit it to the sink. Since the nodes are not statically routed, constantly monitored or secured, they are susceptible to a large array of attacks.
WSN networks are ubiquitous now. They are assisting future technologies to acquire reliant and fault-tolerant abilities through sensing. For now, WSN is assisting IoT in performing non-intelligent tasks. Newer applications of WSN are rising every day and security frameworks need to acknowledge that. We can easily automate most of our lives by leaving redundant tasks to machine, but there must be checks and balances to assure that these systems can't be compromised to leak important or classified data. Security is a big part of WSN, but a holistic architecture or solution is not developed yet. The study aims to assist future researchers in ascertaining the work done already and future issues to deal with. We tried to deliver the latest innovations and holistic view of WSN in terms of its security, architecture and future research directions.