Abstract
Due to the rapid growth in sensor technology and embedded technology, wireless body area network WBANs plays a vital role in monitoring the human body system and the surrounding environment. It supports many healthcare applications on the one hand and are very much help full in pandemic scenarios. It has become the most innovative health care area, which is intriguing to many researchers because of its vast future prospective and potential. Data collected by different wireless sensors or nodes is very personal, critical, and important because of human life involvement. WBANs can minimize human to human contact, which helps stop the spread of severe infectious diseases. The biggest concern is the maintenance of privacy and accuracy of data is still a hot area of research due to nature of attacks, which are changing day by day and increasing, as well as for the sake of better performance. A suitable security mechanism is a way to address above issues, for achieving data security, it is expedient to propose a mechanism. It is essential to update the patient’s regular data. WBANs help to deliver truthful reports related to the patient’s health regularly and individually. This paper proposes an algorithm that shows a better result than the existing algorithm in their previous works. This work is all about proposing a mechanism which needs comparatively less resource. Only authentic entities can interact with the server, which has become obligatory for both sides, keeping data safe. Several authentication schemes have been proposed or discussed by different researchers. This paper has proposed a Secure and Efficient WBANs Authentication Mechanism (SEAM). This security framework will take care of the authentication and the security of transmitted data.
Introduction
WBANs are very useful and the latest technology to secure the patient’s data by storing them into the data sets, which have been received from wearable devices. WBAN can detect important signs and provide real-time data related to the user as well as medical personnel. This has become the most challenging field to monitor and update the data of human health, that too in real-time with the help of very tiny wearable sensors. These wireless sensors play an important role in the mundane life to estimate their regular health issues. It helps you to update the human’s health to get it monitored regularly. Wearable wireless sensors are using a lot in the medical field, such as Electrocardiogram (ECG) to monitor the heart health; a smartphone with many apps to detect the mundane task has been done for the day/week/month, PDA, smartwatches, and so on. Several resources help detect the human body’s health through the sensor nodes included in devices.
It is visible in Fig. 1 that how WBAN can be represented and could work in the human body. In this diagram, the three-tier of WBAN’s general architecture has been represented. It has shown the process of how data goes from a person to the machine. It helps to take input about the person’s health, and then it processes through the technology to the system to access the real-time data. The work has shown the reliable model of WBAN, which will be helpful to secure the data on a real-time basis so that they could save the crucial patient’s data from the intruders being attacked.

General Three Tier Architecture of WBAN.
On the other hand, it is visible in Fig. 2 that shows wearable sensors’ placement in the physical body of human beings. The crucial data related to the patients and doctors during treatment is important to be in knowledge of doctors, patients, nurses, scientists, support staff, insurance companies, and researchers. Using the WBANs devices makes the user report real-time data so that it will be easiest and convenient to track the information related to the user on their real-time mobile location, making it easier and more convenient than ever for the users. Wireless system’s openness has become the most crucial concern to data prone related to the patient.

Placements of wearable wireless sensors into the body.
Figure 3 has shown the vulnerability of WBAN; it is not safe because of the distance of sending and receiving data. Many intruders can attack the various sides of WBAN. The patient system to the doctor’s device carries crucial data, which is important to be secured. The number of architecture is there to secure the data, but still, it requires more security to prevent the data from being accessed by the intruder. As we all know about the advantages of WBANs, similarly, it is very vulnerable to receive an attack from any intruders. Many prototypes secure the data within the WBANs, as proposed by many researchers [1, 25], and still ongoing to make it more secure. The most important part of the scheme is to secure the stored as well as transferred data, to maintain the privacy of data that meant to be accessed only by their authorized users [1]. Many issues such as data confidentiality, integrity as well as dependability are the most important needs to maintain the distributed data storage in the WBANs. In such cases, the prevention of patient data that is important and confidential at a local server or in a node. All the apps are running on smart devices as well as on smartphones by using the internet connections, the capability to store in the cloud, and using offload computing, which has been suggested in terms of overcoming the scarcity of wearable devices [2, 3]. It has been scaling too many servers, central nodes as well as a system.

Vulnerability of WBAN.
These days various types of variants you may find out in wearable sensors, as shown in Fig. 4, the pattern to put the wearable device into the body than help any device to get tracked the human body through its advanced technology is helping people to maintain their health.

Wearable sensors.
In Fig. 5 shows the interfacing between the human and the device through the wearable device. Wearable devices, as well as the other interfacing devices, are helping people. They are easy to place and easy to track if you fulfill the required requirements of those devices where it needs to locate in the human body to track their health reports as per the Transparency Market Research, which has been made by the work done in the paper [4].

Interfacing in between human and any WBAN device.
Wearable devices help a person to track their real-time data of working as well as to help in figuring out about their body illness, which has become easier through the help of such technologies. Many developments were there that made remarkable enhancement in scientific research as well as practical experience in the field of BAN and WBAN serves pervasive wireless communication services [5]. The objective of this paper is to develop a framework that proposes an authentication mechanism followed by securing client’s data in WBAN. This novel framework objective is to provide. an authentication mechanism to confirm the integrity of the two communicating entities. Another objective is to secure (transform/encrypt) the clients (patient’s) data. Next is to perform computation (patient’s data analysis or any other basic operations) on the transformed data (without re-transformation/decryption). The final objective is to validate the results obtained after performing the operations on the transformed data.
There are very intruders, so the system needs more security over the threats. WBAN is already divided into categories, some of them depend on the external devices [2, 6–8], and some do not depend on the external devices [3, 9–13]. The major drawback of using the external device is the requirement of the device for all the time to wearing it. It may be stolen or lost; then, personal data may suffer during the time of unavailability of using external devices. The architecture [14] represents the major challenges of the network; it tells about how to make data encrypted and how to make data accessible to the users. Barus et al. [10] have been introduced a scheme that helps to control the access of patient’s crucial information related to their health by using several levels of their privacy. There is also an analogous protocol introduced by Akinyele et al. [8]; the protocol introduces in it is using Attribute-based Encryption (ABE) to produce self-protecting EHRs that help data to get stored in the storage of either user’s cellphones or in cloud servers. Bourbakis et al. [15] proposed a platform to relate healthcare by using their mobiles that help to secure their required information through the wearable devices to monitor via their systems. Yi et al. [13] proposed a new protocol that has sensors that store three different keys in each sensor. It helps to provide authentication of various three data servers. In which, if any third party has the desire to access the data of the patient, then it requires to get the authorization from the three servers which have stored data. Correspondingly, the use of a cloud server helps to reduce the decrypted computational data, which involves IBE, which is assisted by the Cloud-Assisted mHealth Monitoring System (CAM), introduced by Lin, Fang, et al. [3]. Such schemes have four major components: patient, cloud server, trust authority, and the company which provides the monitoring services for mHealth. Diallo, Rodrigues, Sene, and Niu [16] proposed the work that protects the account by stopping any energy sensor’s constraints and the real-time data required for such applications. Most of the work focuses on controlling access to explicit data and assign rights to the authenticated authorized user [9, and 17]. All of these papers concern about the access of an authenticated user, which has the authorized access to any system where data has been stored in the cloud or any server. It is similar to work-related and resembles the same kind of work, which focuses on securing the BAN sensors’ communication with external users who use the CP-ABE. In contradiction of the architecture, as shown in work [18], it takes an approach that is related to the data-centric, in which the data-sink has received data from all the existing BAN sensors. Moreover, the sensors can be encryptions, and because of this, it cannot be able to access the data produced by the other sensor. Lounis, Hadjidj, Bouabdllah, and Challal [11], designed the WBAN that proposes a huge amount of data that has been generated by the networks of the medical sensor. This system makes a scalable infrastructure, which is completely based on the cloud that helps to store the data from intruders by generating an accessible way to data through a secure way. Many works have attained the symmetric methods for encryptions and CP-ABE, which help users to achieve the fine-grained accomplishment with low overhead of computation. A likewise concept has been proposed by another researcher in [19]; in this paper, authors introduce the concept of sharing devices as an alternative of data, which has been shown in [11]. The propagation of WBAN medical devices which is in-network pretends the research on efficient cryptographic services’ architecture such as shown in work [20], which has been proposed the system architecture for those devices which is implantable, where medical functionalities security are decoupled by making them running on two different separated cores. The cryptosystem of CP-ABE has been used in the paper [21], establishes another example of the scheme designed in terms of lightweight schemes, on-purpose to being embedded in the mobiles as well as in the wearable devices. Many other works have been shown in this world, which helps to advance the BAN sensors environment in this technical world of wireless sensors. There is one more SCAN secure processor has been presented in the paper [22]; it supports the authentication by using biometric expressions as well as numerous primitives of symmetric encryption. Many works are there, which is based on the Cipher-text Policy Attribute Set Based Encryption (CP-ASBE), as shown in [12]. In the paper [9], Li et al. have introduced the ABE system for multi-authority attributed to revocation method; it helps to condense the key management’s overheads. It shows the system has been split into the domains of multiple securities, in which each user subset is manageable. Though this methodology has two major issues as shown in the paperwork [23], one is suitable to the KP-ABE systems only and the other one in which each patient must generate and distribute their keys of security which has been authorized to the users, according to the paper [11]. Truong et al. [30] found that Yeh’s [29] previous scheme has been failing to provide key agreement and mutual authentication, which are the requirements for basic security that has been needed for an authentication scheme. Further, they have been introduced a new scheme to take measures for security pitfalls. Their scheme has been built upon the cryptography of an elliptic curve and has been taking credit to provide security against various known-unknown cyber-attacks. Unfortunately, in this paper, we are demonstrating that the scheme made by Truong et al.’s [30] cannot resist offline password guessing attacks as well as impersonation attacks, which is a real, very serious threat against these kinds of authentication schemes. We also put forward an authentication scheme for smart card-based as well as security-enhanced password in the environment of multi-server. The security analysis, as well as its performance’s discussion, is indicating that our scheme has several benefits in terms of both computation efficiency and security property. Thus are more desirable for practical applications.
Mathematical model
Authentication mechanism
The process needs to identify which entity is accessing the information and whether the accessing entity is authorized to access the client information associated with the nodes involved in WBANs. The authentication is a process in which any entity, whether node of WBANs accessing or server, requires proving their claim first before accessing information from the server. The proposed mechanism takes care of the entire authentication process, which lightweight in nature and provides significantly better authentication.
Authentication Phase: Authentication will take place by exchanging just three messages M1, M2, and M3. The propagation of all three messages is shown in Fig. 6. Message M1 and M3 are sent from client to server, while message M2 is sent from server to client. All three messages are secure by SHA-2, i.e., SHA-512 function. SHA-512 has a bit strength of 256 bits, which is thrice more than the bit strength of SHA-1 or RSA-1024 or ECC-192, which has a bit strength of 80 bits. The authentication phase is only to authenticate for any external entity who wants to access the information whether he is authentic or not then if any entity exchanging the data with another whether first authenticate or not the detail of symbol used for authentication is given in Table 1.

Proposed Authentication Mechanism.
Symbol Table
Authentication between a client Ci and a Server S
v
, they can establish a secure channel. Authentication is performed as follows: The Client C
i
enters his credentials C
red
and the password Pwd. Client first computes.
RPwd = W1 (PwdC red ri) and S v = S v i, j ⊕ RPwd .
Then, a random integer is generated
Where timestamp is T
i
, next, the client C
i
sends the request message After receiving a message from C
i
(Client), the server Sv determines the integrity of C
red
and Ti by confirming if |Tc - Ti| ⩽ ΔT, where Tc is the timestamp (current). Client authentication request will be rejected if the condition fails to meet.
Server Sv computes
Where Tj is the timestamp (current), Server Sv sends the message {M2, Q′j, Tj} to the client Ci. After receiving a message from Sv (server), the client Ci first validates the cogency of Tj by confirming if |Tc - Tj| ⩽ ΔT, where Tc is the timestamp (current). After that, it computes
When the server Sv receiving the message M3 from the client Ci, the server Sv first validates the cogency of T’i by confirming if |Tc - T′i|| ⩽ ΔT, where Tc is the timestamp (current). Then, server Sv recomputes M′3 = W1 (Pi ∥ Qj ∥ Ki, j ∥ T′i) and validates if M’3 = M3. If the condition fails to meet, Server Sv aborts the authentication process; else, the client Ci is authenticated by the server Sv. The server Sv and the client Ci computes a key for the session: S es Ky = W1 (Ki, j ∥ Cred ∥ S
ved
) = W1 (Kj, i ∥ Cred ∥ S
ved
).
This authentication process is now completed. The detailed registration phase and exchange of information between user and server shown in Fig. 6.
The proposed algorithm aims to improve the security aspects of the existing algorithm [24], [25] while retaining all the merits of the algorithm. We have proposed a sparse matrix-based security key for the secure outsourcing of the SLE algorithm with certain modifications. The details of the algorithm discussed in the following section, and notation of the symbol is given in Table 2.
List of Symbols
List of Symbols
SLE Problem is denoted as Ax = b.
Transformed SLE Problem is denoted as A′x′ = b′.
Transformed Coefficient Matrix
Transformed vector constant b′ = k1 × b.
Solution vector x’ produced by cloud server
Retransformed solution vector x is calculated as
Sructure-preserving key generation in WBAN
In this algorithm, we have denoted the key pair as (k left , k right ). As in the previous transformations, the structure of the secure key matrices (k1, k2)) are similar. The definition of (k left , k right ) differs from each other. Here the generation of kleft and kright will take place. For generating the kleft, the client will select the three random columns j1, j2, and j3, and it will ensure that the final output of the problem generation algorithm will remain a random dense structure as shown in Key generation Left. While generating the kright, the client randomizes the three rows i1, i2, i3 as shown in Key Generation Right.
Step-1: The client selects 3 random columnsrandom (j1), random (j2), random (j3) where (j1, j2, j3) ∈ j, ∀j∈ { 1, 2, …, n } and j1 ≠ j2 ≠ j3.
Step-2: k left (i, j1) , ≠ 0, k left (i, j2) ≠ 0 and k left (i, j3)≠ 0 ∀ i ∈ { 1, 2, …, n }.
Step-3: Additionally, ∀i = j, ∀i, j∈ { 1, 2, …, n }, k left (i, j) ≠ 0.
Step-4: Even if one can generate non-zero right diagonally, the final output of problem generation algorithm will remain a random dense structure i = n - (j - 1), k left (i, j)≠ 0 ∀ i, j ∈ { 1, 2, …, n }, where the non-zero random number is generated using the cryptographically strong Mersenne Twister PRNG [26].
Step-1: The client selects 3 random rows random (i1), random (i2), random (i3), where (i1, i2, i3) ∈ i, ∀i∈ { 1, 2, …, n } and i1 ≠ i2 ≠ i3.
Step-2: k right (i1, j) , ≠ 0, k right (i2, j) ≠ 0 and k right (i3, j)≠ 0 ∀ j ∈ { 1, 2, …, n }.
Step-3: Additionally, ∀i = j, ∀i, j∈ { 1, 2, …, n }, k right (i, j) ≠ 0.
Step-4: Even if one can generate non-zero right diagonally, the final output of problem generation algorithm will remain a random dense structure j = n - (i - 1), k right (i, j)≠ 0 ∀ i, j ∈ { 1, 2, …, n }, where the non-zero random number is generated using the cryptographically strong Mersenne Twister PRNG [26].
Additionally, in the final key matrix i1 = j1, i2 = j2 and i3 = j3.
Structure-preserving problem transformation in WBAN
As discussed in the previous section, the objective is to secure (transform/encrypt) the client’s data so that even if the data is mishandled, SEAM will make sure that no meaningful information can be traced. Also, the operation (computation) on data will be performed on the transformed data (without re-transformation/decryption of data), followed by the results verification. This section discusses the structure-preserving problem transformation in WBANs; this is a lightweight transformation mechanism.
ProbTrans (φ, k): Unlike the previous ProbTrans (φ, k) algorithm, this ProbTrans (φ, k) algorithm is adjusted as per the structure of the coefficient matrix.
Step-1: The coefficient matrix A is transformed as T = k left × A,
Step-2: as the key matrix k left (i, j1) , ≠ 0, k left (i, j2) ≠ 0 and k left (i, j3)∀ j ∈ { 1, 2, …, n }.
Step-3: T (i j 1 , j1), T (i j 2 , j2)., T (i j 3 , j3) can be determined.
Step-4: The following adjustment can perform on the output
T (* , j1) ↔ T (* , i j 1 ), T (* , j2) ↔ T (* , i j 2 ). T (i j 1 , *) ↔ T (j1, *) and T (i j 2 , *) ↔ T (j2, *).
Comparison
In this section, the proposed algorithmScheme (SEAM) has been segment-wise compared to the existing work, as shown in Table 3. The proposed scheme has two segments. One is the authentication part of the scheme, and the other part of the scheme is to propose a mechanism for securing client’s data in WBANs named Wireless System of Linear Equation (WSLE). First, the comparison of the authentication phase is compared with other proposed mechanisms. Then a second comparison of the proposed algorithm with the existing state of art algorithms. The Truong [30] authentication mechanism uses elliptic curve cryptography, and the proposed authentication mechanism uses the SHA-2 hash function. Truong authentication mechanism fails to handle impersonating attacks and guessing password attacks offline. These are very convincing & solemn kinds of threats. Here we have used SHA-512 (an SHA-2 hash function), providing a bit strength of 256 bits as compared to the other existing authentication mechanism using ECC and RSA, which provides the bit strength of 80 bit-128 bits most of the time.
Comparisons of Computation Efficiency
Comparisons of Computation Efficiency
The work done by Wang et al. [27] proposes an algorithm for secure outsourcing. In the first step, an encryption key is generated by the Paillier method and a safe randomized encryption vector. After this, the transformation of the problem requires the multiplication of three matrix-vectors. The comparison of the complexity of (SEAM) with other suggested algorithm/scheme is given in Table 4.
Theoretical Analysis of Complexities for SLE Problem
Theoretical Analysis of Complexities for SLE Problem
Abbreviations used in the proposed Wireless System of Linear Equation (WSLE) algorithm are listed in Table 5.
Terms and Notations for SLE Algorithm
Terms and Notations for SLE Algorithm
Te = time required by mod exponent; Th = time required by hash process; Tm = time required by addition over ECC; TXOR = time required by XOR process; Tp = time required by multiplication over ECC.
Next, a case study is considered to ensure that the objective# 2, 3 & 4, i.e., lightweight data transformation, followed by performing computation on the transformed data and finally the results verification is achieved successfully by the proposed WSLE algorithm. The data matrices generated are equal to the size (matrix dimension) of the problem. Performance Analysis for Proposed WSLE Algorithm is given in Table 6. Comparison of Performance Gain for the proposed wireless SLE Algorithm is shown in Fig. 7.
Performance Analysis for Proposed WSLE Algorithm

Comparison of Performance Gain for SLE Algorithm.
The comparative analysis of different possible attacks that can be handled by the proposed algorithm is given in Table 7, which is not addressed by studies given in Table 7.
Comparisons of security’s parameters
*DNH: Does not handle HNDL: Handles.
This work proposes a novel framework that provides data security in WBAN with an authentication mechanism. This proposed WSLE algorithm, which provides authentication between the communicating entities and data security by using a lightweight transformation mechanism, has been proposed for the first time for WBANs. The work proposed provides security and is capable of handling the following attacks, namely, COA: Cipher-Text Only Attack, KPA: Known-Pain Text Attack, CCA: Chosen-Cipher Text Attack. Known-Pain Text attacks are handled by using different keys, and this holds true for Chosen-Cipher Text attack. Random results are generated by transforming the problem for every matrix passed as input. So, the unauthorized user is never able to detect the raw input by the transformed input. Also, the WBAN server is not able to recover/detect the raw input from the transformed input, and an unauthorized user is not able to distinguish between the two transformed inputs. So, the proposed WSLE algorithm can handle the attack. There are various kinds of attacks that need to be secured for future work. WBAN is an open network, which makes it more vulnerable to every type of intruders. The proposed work (SEAM) has tried to secure the WBAN from CCA, KPA, as well as COA. The authentication mechanism uses the SHA-2 function that provides the property of one-way and collision resistance. The property of being one-way ensures that no one can learn anything meaningful about the input from the output of the hash function. The second property of being collision resistant ensures that the same hash cannot be produced again for any given input. At the same time hash functions are primarily used to ensure integrity.
Footnotes
Acknowledgment
This work is carried out in Secure and Computing Laboratory, SC and SS, JNU, New Delhi, India, and sponsored by the project entitled “Development of Intelligent Device for Security Enhancement (iEYE),” PID-DST/TDT/DDP12/2017-G.
