# Cryptographic Protocol with Keyless Sensors Authentication for WBAN in Healthcare Applications
## 1 Introduction  
A wireless body area network (WBAN) is a wireless network of heterogeneous sensors placed in different parts of a human body [1]; the sensors can be wearable or implanted under the user's skin. WBANs will be relevant and helpful for monitoring the population's health. WBANs can be used not only on remote patients but also to enable the wireless monitoring of patients within hospitals. According to the World Health Organization (WHO), between the years 2000 and 2050, the population over 65 years old will go from 605 million to 2 billion people [2]. WBANs use low-power signals to reduce interference between devices, and the transmission distance is not greater than 2 or 3 m. Thanks to this, doctors can monitor patients' health in real-time; thus, their health records are always up to date. The Health Insurance Portability and Accountability Act (HIPAA) provides a series of regulations on securing a patient's information [3]. In such regulations, it is stipulated that privacy and confidentiality are essential characteristics to have on monitored patients. Despite this, security is often overlooked, and patients could be exposed to a cyberattack that could put their health and life in danger. In this context, several cryptographic protocols have been proposed that ensure authentication and only use confidentiality and integrity as support for maintaining authentication. A WBAN is secure if it ensures privacy, confidentiality, integrity, and authentication. However, the limited power and infrastructure of WBAN systems provide a challenge in implementing such measures. Authentication is a very crucial aspect in any network of communicating devices. Traditionally, the authentication process has been related to pre-distributed secret keys among nodes in a network. Nevertheless, WBAN's usersare usually security inexperienced, which requires high usability of the authentication process, minimization of key distribution/management, and needs to be automatic and transparent to users. Node authentication mechanisms in WBAN should have minimal reliance on cryptography. Finally, low-end medical sensors are extremely constrained in resources, while non-cryptographic authentication mechanisms mostly require advanced hardware [4; 5] or significant modifications to the system's software. Node authentication in a WBAN is of great concern as it can compromise the privacy of the entire network. Hence, this paper presents a cryptographic protocol that guarantees the security services of authentication, confidentiality, and integrity applicable to WBAN. The research question considered in this approach can be stated as: Can cryptographic primitives combined with a key-free authentication method improve the security of transmitted data over a WBAN used by doctor-patients activities at any time, any body area, and anywhere? The proposed protocol makes use of a non-cryptographic sensor authentication method that does not depend on pre-shared secrets between nodes. In the same way, cryptographic primitives, such as the key encapsulation mechanism, digital signature, and hash functions, are used to guarantee security services on the information transmitted. Current protocols use cryptographic primitives to preserve security services, mainly authentication and confidentiality. The main primitives used to preserve these services include encryption, key encapsulation mechanism (KEM), digital signatures, and hash functions. Cryptographic protocols help protect the information, minimize the confidence required between participants and face security breaches when these services are absent [6; 7]. There are different types of attacks that can be made to protocols. These attacks usually involve obtaining a determined entity's values to pose as a legitimate source.