# REISCH: Incorporating Lightweight and Reliable Algorithms into Healthcare Applications of WSNs
## 1 Introduction  
Medical records of patients require accurate, secure, and efficient electronic systems to be managed and organized. Electronic medical record (EMR) systems are extremely useful for managing patients' data. These systems are widely disseminated in the health sector [1]. Moreover, EMR systems need patients' data collection technology such as a wireless sensor network (WSN). This technology consists of a group of sensing nodes that communicate wirelessly with each other to gather data about a particular environment in various applications. A WSN often has limited resources such as energy and memory, but it provides comfort, speed, accuracy and safety to humans by monitoring a specific area without human intervention or presence [2]. An important application that has brought the attention of sensor networks to many researchers is healthcare (HC), because of great importance in our lives to reduce the effects of diseases on the health of patients. Providing better HC quality of lower cost will be a key aim of all health industries over the next decades [3]. These applications relying on the use of WSNs are known as healthcare wireless sensor networks (HWSNs) [4]. By using HWSNs, healthcare providers including physicians, doctors, and nurses can access data and information about patients on an ongoing basis, whether at clinics or in hospitals. Therefore, this medical record leads to more accurate diagnosis and thus is likely to lead to an improvement in the patient's condition. For many diseases that require constant monitoring and precise care, HWSN is the best method used by doctors to get patients' data, as this technology provides patients with comfort and more care at less cost [2]. Since these applications monitor patients' activities without interruption, accurately and continually, they should lead to an improvement in their health condition [5]. Disclosure of medical records for patients in the HC systems results in weak security in these systems. In addition, some security mechanisms such as public key signing significantly affect WSN performance. Therefore, several issues need to be addressed when designing schemes for collecting data in HC applications. These issues are critical to the acceptance and success of HC applications in the healthcare sector. These issues listed are as follows:  
* **Communications security:** To protect data and information between source and destination, security mechanisms, such as signatures should be applied to prevent an attacker from accessing records transferred between network entities (for example, sensor, Cluster Head (\(CH\)), and Base Station (\(BS\))/Local Server (\(LS\))). These mechanisms should resist attacks such as disclosure, alteration, replication, collision, preimage, and impersonation of medical records transmitted. The communication channel should be protected end-to-end at both the wireless level and on the Internet through the integration of a set of security mechanisms and privacy [6; 7]. * **Datasets security:** Medical records stored on the EMR server as a repository become the target of malicious attacks. In particular, if a HC application is based on a single server, the process of hacking this server results in both data and information being detected [8]. Besides, access to datasets without pseudonyms and signature mechanisms makes it easy for attackers to detect users' real identities (IDs). To protect users' medical records, the EMR server should not contain real information for users to prevent detection of users' identities or tampering with datasets. For instance, an EMR server contains only signatures and pseudonyms and users' identifiers are stored on the remote server, such as an Attributes Server (\(AS\)). Furthermore, the database should be available to legitimate users at any time and from anywhere, and should support authorization requests for access to partial data from an EMR repository and patients' history from a remote server, such as a Data Server (\(DS\)) [9].