Blockchain and ANFIS empowered IoMT application for privacy preserved contact tracing in COVID-19 pandemic.

Life-threatening novel severe acute respiratory syndrome coronavirus (SARS-CoV-2), also known as COVID-19, has engulfed the world and caused health and economic challenges. To control the spread of COVID-19, a mechanism is required to enforce physical distancing between people. This paper proposes a Blockchain-based framework that preserves patients' anonymity while tracing their contacts with the help of Bluetooth-enabled smartphones. We use a smartphone application to interact with the proposed blockchain framework for contact tracing of the general public using Bluetooth and to store the obtained data over the cloud, which is accessible to health departments and government agencies to perform necessary and timely actions (e.g., like quarantine the infected people moving around). Thus, the proposed framework helps people perform their regular business and day-to-day activities with a controlled mechanism that keeps them safe from infected and exposed people. The smartphone application is capable enough to check their COVID status after analyzing the symptoms quickly and observes (based on given symptoms) either this person is infected or not. As a result, the proposed Adaptive Neuro-Fuzzy Interference System (ANFIS) system predicts the COVID status, and K-Nearest Neighbor (KNN) enhances the accuracy rate to 95.9% compared to state-of-the-art results.

Introduction

COVID-19 has put the lives of many at severe risk and turned out to be one of the most challenging viruses to deal with globally (in the present times) [1, 2]. Its method of spreading is direct (when a human contact with another human) that is why creating physical distance between people is one of the most critical instructions laid out by the World Health Organization (WHO) with the following parameters1: (1) distance of at least one meter between people, especially from those who seem to be infected with respiratory problems, (2) staying at home most of the time, (3) avoidance of traveling and prevent gatherings of people.

Worldwide, with thousands of people dead and millions affected, it seems that COVID-19 is still staying undefeated for a long time [1]. Its remedy is not discovered until now. To reduce the damage caused by it is by placing a lockdown and limiting people’s movement. However, on the other hand, the world’s economy is also suffering much due to reduced business activities2. People are losing their jobs, salaries being cut off due to business losses, and bringing the world’s economies into a terrible situation. Therefore, it is crucial for society’s survival that a section of it continues with its business activities [3, 4]. The need of the time is to develop a systematic approach to deal with the restrictions laid down by governments. An approach that enables businesses to carry on with their activities (in a reduced and restricted capacity) keeps things running.

Standard operating procedures are to be developed and followed to ensure protection with activities being carried on within them. Smartphone consists of multiple sensors and actuators (i.e., GPS, accelerometer, gyroscope, magnetometer, Bluetooth) [5-8]. Some of the countries tackled the situation by using smartphone technologies such as Bluetooth and GPS, which enables people to have awareness about those who met the infected ones (so that they can keep their distance). In this way, measures can then be taken to protect oneself from infected people diagnosed with this virus, and their location data is accessed using smartphone technology. Business activities must be allowed to take place in a restricted manner3. However, these smartphone applications should be designed to provide people with information about infected people beforehand. The distance can be maintained from them and updates them about people planning to meet with them. Areas that are hotspot zones of spreading should be marked out; they can be avoided, and further protective measures can be taken to protect physical contact with the people who went inside those zones. However, applications of such type rely on people to a large extent who must feed in the data that everything needs to be updated. Data collected using these applications should be available to the public for usage; individual businesses can benefit.

To control the spread of the COVID-19 virus, every country is struggling to employ smartphone apps, but there are exist some security, vulnerability, and privacy issues [9-13]. Some apps forcefully get the user data and IDs without any encryption and decryption techniques, which is a big question mark to preserve personal data privacy. In addition, some of the apps are designed in a way that sends some push notifications to the users with a backend and can get compromised by DDoS attacks. In this paper, we propose a blockchain-based system that effectively protects the user from getting infected with the COVID-19 virus in which every single piece of information exchanged between persons and authorities is protected using Blockchain. Smartphones work as electronic keys for the exchange of data between different stakeholders. One of the different aspects of our research is that most of the apps are only used for contact tracing, but we also predict whether a person is affected or not affected by COVID-19. Information gathered by almost all applications is saved in one place, which is under single control, but in the proposal that we are storing, the gathered information is saved in a consortium blockchain in the shape of a distributed ledger.

Contribution

We propose a Blockchain-based framework that preserves patients’ anonymity while tracing their contacts.

We use a smartphone application to interact with the proposed Blockchain framework for contact tracking using Bluetooth.

The proposed framework helps people perform business activities with a controlled mechanism that keeps them safe from infected and exposed people by predicting the COVID status using ANFIS and KNN.

The proposed framework effectively keeps the anonymity and enhances the detection rate of COVID individuals.

Organization of paper

The rest of the part is formed as follows. Section 2 provides the literature review. Section 3 provides the structure of the ANFIS system. Section 4 provides the proposed methodology for COVID detection. Section 5 contains the implementation of the proposed structure. Section 6 provides the Discussion, and Section 7 concludes the article.

Literature review

Throughout the world, countries have not only developed mobile phone applications to tackle coronavirus disasters but are also using data gathered from it to make their decisions about lockdowns in a smart way [14]. Australia4, China5, South Korea6, and Singapore7, are the countries which have taken leading steps by advising their citizens to install these applications for surveillance purpose, in India, an application called Aorogya-set was designed for this purpose8. However, such procedures undertaken by governments lack the needed privacy protections in their mechanisms, which risks people’s data. Concerns also arise for these applications for being used for purposes other than what they were designed for. For example, an app designed by South Korea uses data from GPS location, which forces citizens to provide their data such as their name and ID numbers9. It shows no sign of privacy in the system designed for tracing a contact, and track of a person can be done very quickly whenever desired and at any place. Application designed by Singapore, called Trace Together, anonymously saves Identities and uses Bluetooth identities transmitted between nearby phones using encryption. This use of encryption ensures that a government organization can only decrypt the encrypted data and, therefore, ensures privacy to some level (to the ministry of health), which holds its key. Application Aarogya-set designed by India captures data of the user’s location and connectivity of Bluetooth (when installed); it is then forwarded to the Government servers, enabling them to know about app users’ locations and movements. This is a sort of comparison that enables them to determine if the user was in the proximity of someone who was tested as positive with the coronavirus. The user’s location is prevented from sending to government servers and comparing location data on the user’s smartphone. The history of the location and the proximity of WIFI Networks that the application user entered is saved on the smartphone for two weeks. Versions that come later determines connections of Bluetooth and data. At some time in the future, they plan to make the application open source.

Private companies also participated as it presented them with an opportunity by making mobile applications to facilitate users. For example, PHBC10 is an association of different health stakeholders like universities, government agencies, healthcare providers, etc. It has designed a blockchain for record saving of virus, enabling the observance and checking of work sections & land areas with no coronavirus spread11. These zones are called corona-free zones. Its mechanism finds the movements of uninfected persons in the proximity of an area where coronavirus spread then tries to restrict their entry back into the clean area, forcing them to stay in a quarantine zone spend some time before coming back to uninfected areas. It happens with a combination of GIS and AI technologies that gathers data in real-time from virus infection information-providing agencies.

Researchers in the field of IT have come up with a proposal of different approaches to prevent the spreading of the coronavirus [15]. There is a proposal of Blockchain and a four-layer framework based on AI where data of coronavirus is gathered from different sources like laboratories, social media, hospitals, data generated by patients, and operators of wireless networks. They propose to make sure the privacy of data through the use of Blockchain. Models of AI can then harness the gathered data to provide solutions to estimate an outbreak, detect the virus, analytics, and assistance in developing vaccines and predict the same outbreaks that can happen in the future. However, this framework is yet conceptual, and it does not also provide details of implementation.

COVID watch, a volunteer assemblage that is spread out around multiple countries and continents and comprises security, policy, and experts of public health [16]. This group has developed an application for smartphones to reduce the coronavirus’s spread using a Bluetooth-based system and preserve privacy. This mechanism works by generating random numbers when an application user is near another user. It happens using Bluetooth signal strength. A data record is saved in each phone for every different contact number (the smartphone sends or receives). When any of the users of this application is tested positive with coronavirus from a health facility of locality, it then provides with approval amount that after verification is forwarded to a server which is public in its property along with a previous record of person’s received and sent numerals (which are randomly generated) and is also forwarded to the other smartphones. If one of the smartphones search and locate another matching with its saved data of random numerals, it would mean that the smartphone owner was within proximity of the person diagnosed with coronavirus. However, there can be a compromise with this mechanism. Can there an attack from a middleman on the connection of Bluetooth? Furthermore, this application is made for tracing contact only. However, many additional data can be gathered, consisting of massive epidemiological purposes, but the application is not made for such purpose.

Authors in [17] suggest an application which is smartphone tracing and confidentiality protective, named as WeTrace. Mechanisms are designed for smartphones with this application loaded in them (broadcast the public key generated by the app periodically). Like COVID-Watch, other smartphones nearby (which is determined using Bluetooth with a low energy level) save these public keys locally. When there is a change of status by the users from healthy into diseased, messages coded into the whole of public keys and present in its stores (that are local) and then forwarded to the back end, it then publishes it to everyone. People that found it in the area who came close to this person can then decode the message using their key, and in this way, they can become aware that they went into proximity of an infected person [18]. Authors in [19-21] discussed large-scale mainstream blockchain consensus protocols and presented technique for anonymity preservation and COVID-19 detection.

No data is saved in the backend; it only serves to broadcast the messages to smartphones within the system. However, as also known by its developers, such a mechanism may go through DDOS interventions on the back end. Therefore, there is a possibility that the backend becomes vulnerable to fake users who may raise wrong notifications. Authors in [22] also proposed a framework based on Blockchain for tackling the coronavirus spread. It is based on four subsystems — the infection verifier subsystem (IVS), P2P Mobile application, Blockchain platform, and mass surveillance system. The IVS is a section of this mechanism that saves COVID-positive people within Blockchain using patterns of infection (that are continuous expressions). Patterns are derived from these continuous expressions; infection instances are then used to represent places or people (contaminated by that diseased person). These are saved in the Blockchain as well. Limited automation can confirm if the continuous expression instance follows the infected pattern, signifying a high infection probability level. Using people’s representation as continuous expressions, the mechanism does its job in anonymizing the application user. These instances are also then used in the proposed P2P smartphone app. In their mechanism, the authors use Blockchain for saving the patterns of infection and all the cases that are confirmed and are infected instances, which are pattern-based. Thus, the P2P app notifies people that they may have gone into contact with a diseased individual or may have been in a location visited by a diseased individual. The mass observation structure part is held liable for tracing contact and identifying the public places the diseased person went to in the past, then forwarded to the Blockchain to save it as infected patterns. However, it is not yet clear which communication technology is used to implement this mass observation mechanism.

According to authors [23], presented a Blockchain-based digital tracing app based on challenges, issues, solutions, and future directions for the COVID-19 pandemic. The authors involve a cloud app for the security and privacy of the proposed Network. According to [24], presented Blockchain technology in Internet-of-Things(IoT). In this paper, the authors focus on privacy-related issues and present different algorithms for a privacy policy. According to [25], presented a Blockchain-based contact tracing for COVID-19. They proposed a beep trace approach for software developers, Companies, authorities, and researchers to overcome this pandemic. According to [26], proposed a practical approach to support the government and individuals in deciding against this infection. Through this system, we can predict the infection and its avoidance. It consists of four components that help us to escape this viral infection [27].

According to [28], the author proposed an architecture to validate COVID-19. The proposed system ensures trust, transparency, and updates between investors in the Network. The overall system is based on Blockchain technology. According to research, [29], the author presented a review to escape from the COVID-19 pandemic and provide possible solutions to reduce it. Authors have discussed many approaches of Blockchain technology in this paper that help save us in homes until a vaccine is developed. Authors in [30] presented a scalable Blockchain platform for securely sharing the diseases vaccination certificates of COVID-19. The authors simulate a large-scale placement by considering different countries. The proposed work is a novel approach on a large scale. The results are pretty clear that we can quickly secure our documents or certificates by these criteria.

Various algorithms and methods are used to predict the COVID-19 status in literature. In this research, we use the KNN algorithm and ANFIS for COVID-19 prediction. Our primary purpose is to achieve a maximum accuracy rate by KNN and predict the COVID status using ANFIS after entering the individual symptoms in a Blockchain-based app.

Adaptive Neuro-Fuzzy interference system

Adaptive Neuro-Fuzzy interference system is a technique of data learning that is quite simple in its functionality; its fuzzy logic changes inputs into outputs required by being highly interconnected. Numerical inputs are mapped into output by the weighting of neural network processing elements and information connections. ANFIS achieves its great success by the following features:

Behavior of a complex system is described by the refining of fuzzy IF-THEN rules.

Prior expertise of humans is not needed.

Quickness and accuracy in learning are enabled by it.

Required set of data is offered by it, membership functions to be used with greater choice, strength in generalization abilities, fuzzy rules being used for excellent explanation. Based on features, Fig. 1 shows the architecture of ANFIS.

Fig. 1

ANFIS architecture

Blockchain overview

The Blockchain, an idea that was initially introduced into the white paper of Bitcoin by Satoshi Nakamoto in 2009 [31]. Blockchain is a data-saving technique that is decentralized and kept like a distributed ledger. The following are some of the features that have encouraged us to use Blockchain in our proposed framework [32-34]. Some of the blockchain features are shown in Fig. 2 and explained below:

Fig. 2

Blockchain features

Autonomous: Blockchain transactions do not involve any control of central authority or any governing network. It gives us the benefit of being a decentralized system architecture with a reduction in operational costs. We are not limited to the bottlenecks of geo coordinates. Some of the blockchain computers could add and recheck transactions at any instance in the blockchain system.

Distributed: Blockchain transactions cannot be changed or accessed by anyone as they are stored in blocks (distributed on the overall Network). Each Block is authenticated by nodes, due to which any transaction & changes that appear to be false can be easily detected.

Immutable: Blocks and transactions are added in chronological order in the blockchain ledger, and every transaction can be verified and traced. Blockchain follows a consensus mechanism central to synchronizing all the transaction chunks (in every computer). This makes sure the information stored in Blockchain could not be changed or changed by any means.

Consensus Based: In the Blockchain, new blocks with transactions are only supplemented if the previous blocks are agreed upon adding them up, which is named as agreed technique. Every blocks and beneficiary refresh their ledger by including similar Block to their effective blockchains by a consensus mechanism. This ensures that everyone gets an exact duplicate of Blockchain, which is coordinated among the rest of the individuals at any given specific time.

Anonymous: Data regarding the persons is stored in a randomly generated location; hence, it hides the real identity and facilitates anonymity in data storage of individual records. Every time a new transaction is broadcasted between the nodes and miners adds that new transaction into the Block (based upon the consensus algorithm). In Blockchain, nodes can be computers, mobile phones, and other similar devices which contain the blockchain copy. Miners are nodes that develop blocks and create new transactions after validation and adherence to the consensus mechanism. The consensus algorithm is responsible for mutual trust and helps the decentralized Network to decide whether to add the transaction or Block in Blockchain or not. Proof of Work, Proof of Existence, and Proof of Existence are the standard consensus algorithms [35].

Proof Work: Various cryptocurrencies like BitCoin used the consensus mechanism is called Proof of Work. It is mainly popular because of its security along with protection from different attacks. This mechanism is selected for validation of transactions with the addition of the new blocks to the chain. Miners do this; each Miner has to solve the complex computations problems. Miners compete to find a solution to the hurdle and make blocks, and one who solves the problem first can add a new transaction in a block and claim its reward.

Structure Blockchain

The structure of Blockchain consists of a block header, and the block body is arranged in chronological order. Each block stores hash of the last Block, timestamp, Merkel root with its data. Every transaction block in Blockchain consists of the previous block hash value, which ensures all the blocks are related, and alterations cannot be done in any of the blocks unless changes get imitated in every following Block. Due to these hash values, it is impossible to change the data. Every Block contains transactions in it, and all transactions have a hash interlinked with. Pair of hashes are concatenated to calculate the other Hash, and it carries on, which makes a tree of hash values. The Hash of all the transactions a block contains is called Merkel Root. Merkle Root preserves the integrity of the transactions in a block; altering any one transaction changes the Merkle root. Reliant upon different scenarios, we can categorize Blockchain into Public, Private, and Consortium.

Public Blockchain: In a public blockchain, ledgers are open and transparent as they are fully decentralized. As a miner or a node, anyone can be a part of the public Blockchain without restriction. Etherum, Bitcoin, etc., are some examples of a public blockchain.

Private Blockchain: Private Blockchain follows a set of conditions, like public Blockchain. An organization controls a private blockchain, and access is limited to those who have permission from a private Blockchain’s governing organization. A private blockchain is a decentralized peer-to-peer network, and the organization decides the participants in the Blockchain. Hyper ledger is one of the examples of Private Blockchain. The structure of Blockchain features is represented in Fig. 3.

Fig. 3

Structure of blockchain features

Consortium Blockchain: This type of Blockchain involves companies and beneficiaries to make a complete Blockchain. A consortium blockchain is partially personal and public Blockchain and can also be said as a semi-decentralized blockchain. In Consortium, the blockchain-specific group determines the validation of blocks and consists of a pre-determined group of nodes. Examples of Consortium blockchain are R3, Libra, and EWF, etc. Cryptocurrency is mainly based on Blockchain technology, and one of its more popular examples is Bitcoin which uses blockchain architecture to store the distributed ledger of transactions. Other than the cryptocurrencies, Blockchain is now transforming various other aspects, some of which are discussed as follows:

Electronic Health Records (EHRs): Blockchain is now being used in keeping health records of patients in preserving their overall medical history without any involvement of service providers. Traditionally these health records of patients are preserved by the hospitals [36]

Cloud Computing: Operations carried out over the cloud data element are critical, and metadata keeps the record and history of all such operations. Blockchain-based data provenance architecture is used to ensure transparency of such data, which provides tamper-proof records and can enhance data provenance.

Internet of Medical Things: In IoMT, the blockchain-based access control model uses smart contracts to get related access control rules to decide authentication selections. This ensures the user’s privacy by skipping the third party to implement and handle the control policies [37]. Based on the benefits of the blockchain technology that we described above, we can think that it can contribute a lot in the development of a platform to fight against the COVID-19 pandemic provided with inborn perks of blockchain mechanism, it was thought that it could participate a lot in constructing a station which could be used in the battle against the spreading of the COVID-19 virus.

Proposed framework

We propose a framework to save people from getting infected by the coronavirus infection when carrying out their daily tasks. For example, people could operate mobile like an electronic key which they can use to convince the government authorities, institutions, and business establishments that a person is not infected from coronavirus. It enables people to go around with a free mind without having a restriction which is a hurdle for them to carry out their tasks, and to some, it allows an impression of everyday routine life. Those people who fail to do this then be implied that the person is under quarantine or is infected, and he should not be moving around freely in places where there is public. Such places are protected as diseased individuals do no visit them and make them infectious and force them to stay in quarantine. We propose the usage of Blockchain technology for keeping data privacy using apps. The coronavirus status of people with their relevant details like age and previous medication situations can be uploaded in the Blockchain (while ensuring people’s anonymity and privacy). All the stakeholders are made available with this record of the public. Provide the fundamental characteristics of Blockchain, the ledger then be provided to stakeholders with a read-only authority. All these beneficiaries can add parties like health centers of the state, offices, federal or central government, development centers, medical research, business houses, private hospitals, and other organizations. The proposed framework is shown in Fig. 4.

Fig. 4

Blockchain-based framework for protection against COVID-19

The proposal work is different from most of the applications developed to analyze the spread of COVID-19. The following are a few aspects that are different regarding those applications: Business houses, development, and research centers are also nodes, and they only have read-only access to the Blockchain. Their interest lies in the information getting appended in Blockchain for business and research. These types of organizations are also able to participate as block evaluators in the system. Institutes, shops, offices, etc.: These establishments are allowed to access the ledger by a government node or business house on a read-only basis. Their interest lies in data, which is being produced. It can be used for their business activities to run smoothly.

Majority of the applications are designed in a way that to trace and alert those people who meet people infected with COVID-19.

This framework assists people in taking protective measures regarding their health.

Their behavior in society. Further to this, in our framework, the focus is diverted to another problem, which permits those people who do not test positive with the coronavirus to continue their economic activities while at the same time protecting them from coronavirus.

The Information gathered by almost all applications are saved at one place which is under single control, but in the proposal that we are offering, the gathered information is saved in a consortium blockchain in the shape of a ledger which is distributed, and it is possible to get access any of the parts of society.

An approach of such kind enhances transparency and permits the people to garner its benefits. Furthermore, it helps prevent misconceptions regarding the present form of infection as trustable data is accessible to everyone and at the same time.

The anonymity of people and incentives for stakeholders would be considered when it comes to stakeholders, entities related to design.

Medical Professionals: These are people performing random testing. Further to their kits used for testing, they are added with mobile, Bluetooth, and internet connectivity. However, their access is only ready-only for the ledger, and it produces transactions based on the status of COVID-19, either positive or negative, derived from their test reports that are further based on their period of quarantine which is needed.

Hospitals/Clinics/Laboratories: They are given authority to the ledger on a read-only basis and can produce transactions that comprise individuals’ status if they are COVID positive or negative on their test reports for their further transfer to block Miner.

Testing Centers: Centers established by the government, which has the facility for COVID-19 testing. These centers are loaded with a mobile phone which has Bluetooth enabled, computer, and internet connectivity. They only have the authorization to access a read-only basis to the ledgers, and they can generate transactions that comprise the status of the test result, which is either positive or negative, and the number of days in quarantine.

Government Nodes: These are the computers developed by the authority with permissions of read-only access to the ledgers. Their purpose is to facilitate testing centers, law enforcement people, medical professionals, and people allowed to have the authority to access the ledger (who are responsible for communication produced by them).

Individuals: Using their mobile phones, they can access the ledger to read-only by a government node or a node connected with a business house. They can use this data to plan and carry out their activities with protective measures taken simultaneously.

Law Enforcement Personals: This includes police officers who can advise quarantining to a person who is tested positive or met an infected individual, which can be known by his travel history, by producing these transactions for further transmission to block Miner. They can also demarcate localities and districts into red, orange, and green zones based on an area’s infection level. This is done that people can be made aware of and be prevented from entering these zones. These people also are providing mobile phones with turned-on Bluetooth or PCs.

Block Miner: This is a node located centrally in Blockchain, and it takes all of the transactions produced by different beneficiaries, which are later on put into blocks together.

Block verifier/Validator: These are those nodes that validate all transactions done by examining their digital signatures. This is in the ownership of either a government /state of a country or is owned/monitored by establishments that are nominated by civil society.

Local Authority: It depicts the local government of a province/state.

Central Authority: Central government of any state.

A mobile phone app used to interact with the COVID chain as an interface. The application requires that the mobile phone being used is Bluetooth enabled. Similar to other applications which are developed recently for the tracing of contacts by Bluetooth. It gathers tokens from mobile phones of those people who came in proximity in an anonymized way for some days in the past. If any individual is tested to be infected from the coronavirus, all of the gathered tokens are then mapped to the contact numbers which are in correspondence, and after that, all people are then made to be tested for COVID-19 or are advised to stay in quarantine by law enforcement or medical professionals. This application includes a self-assessment module, which an individual can use to answer a few questions to assess their health status (based on answers given by the user). Accordingly, he/she is advised to either go into quarantine or go for a test at a testing center, depending on the symptoms’ severity. The whole framework’s functionality is split, including blocks in Blockchain, into the following activities.

Application initialization

When COVIDSafeApp is loaded in a smartphone, a pair of public-private keys is produced by taking an OTP validated phone number, which comes from the user’s input. Therefore, the phone number is neither saved nor used for other purposes. Instead, for all the following purposes, the user uses the public key as an identity.

Generation of transaction

Transactions can be categorized into two types, one indicating individual status called “TI” and the other indicating the status of location TZ. COVID status of an individual determined by a medical professional, testing center, hospital, or law enforcement agency is TI. TI is composed of three components, i.e., individual’s public key Hash (PKI), the current status of COVID for the individual “CS”, the time, the date, and the epidemiologic details of the user like gender, age, blood group, etc. represented as “EiI”, which the government needs to conduct a general study. EiI must have minimal information needed for data analysis and should not contain any personal information that can compromise the individual’s privacy. Before including EiI in the transaction, the encryption is performed by using public key PkCA of central authority. Every transaction has a unique Tid that is the hash figure of the transaction. Every transaction is encrypted further with the private key of the testing center (PkTC) to generate a digital signature of the testing center (DTC) that the block validators can verify the transaction’s genuineness. Equations 1, 2, 3, 4 and 5 presents the parameter for status prediction.

Here “Ef” is an encryption function, and a single-way hash function is represented by “Hf” like SHA-256. Table 1 presents the different symbols and acronyms used in this area for quick reference.

Table 1

List of notations

CoS	COVID-19 infected person’s status
TI	Transaction of Case-Severity (CS) of an individual
TZ	Transaction of CS of a zone
PkI	Public key of an individual
EiI	Individual Epidemiological information
encEiI	Epidemiological information with Encryption
PkCA	Central Authority Public key
Tid	Transaction Id
PkTC	Testing center Private key
DTC	Testing center (TC) digital signature
Hf	Hashing function
Ef	Encrypted function
Df	Decrypted function
La, Lo	Geo-coordinates of Latitude and Longitude
zid	Zone Identity
RoZ	Radius of zone
Zt	Zone Type
DLiA	Law implementation Agency’s digital signature
PkLiA	Law implementation Agency’s Private key

Transaction made by authority or law enforcement agency local, which declares locality or district as green, red, and orange zone, is represented by TZ depending upon the infected people to alert the people from other localities about its vicinity to the infected zones. These types of transactions are helpful for the concerned authorities to gather reliable information for making vital decisions. For example, to map a locality, latitude, and longitude from GPS coordinates, it is required to define the radius of a zone “Roz” zone type “Zt” (red, green, orange) is saved in a transaction. The transaction also includes zone identity “Zid” obtained from the Hash of location coordinate, “Tid” the Hash of the whole transaction, and digital authority signature “DLA” which is derived by the encryption of “Tid” with the law enforcing agency private key “PkLiA”. Below are Eqs. 6, 7, 8, and 9 to calculate these parameters.

Once the (TI or TZ) transaction is generated, it is sent to the Block Miner. Here Fig. 5 represents the blocks in COVIDchain.

Fig. 5

Blocks in COVIDchain

Block miner

There can be multiple servers receiving transactions from all over hospitals, testing centers, and localities in block miners. After reaching the block size to its assigned limit, all the transactions are grouped into blocks. Validation of each transaction in the Block is performed by validating the testing centers’ digital signature that signed it. The Block Merkel Root Hash is derived by pairing all the transactions’ hash values and rehashing the sum of the pair as depicted in Fig. 6.

Fig. 6

Transactions from Merkel Root Hash

After calculating the MRH value, the MRH value is added to the block and MRH is digitalized signed with its private key PkBM. If one block has transactions “Ta”, “Ta”, “Ta”, “Ta”, then the “MRH” and “Habcd” is calculated and digitally signed for this block using Eqs. 10, 11, 12, 13, 14, 15, 16, and 17 shown below:

After the above step, the block miner sends the Block to the number of block verifiers that can be said as “BVer1” and “Bver2” chosen randomly between the present block verifiers as shown in Eqs. 18 and 19. The digital signature of testing centers validates every transaction, and then the Block verifiers sign the MRH of the Block with the private keys of blocks “PkBVer1” and “PkBVer2”.

The signed Block is rolled back to the Block Miner. The Miner verifies Block verifies signatures after receiving Block.

After verification of signatures, the Block is broadcasted to all the nodes available in the Network. Each node adds the respective Block to their copy of Blockchain after the validation of digital signatures. While the Block is added to the Blockchain, the last block hash is also included in the current Block. Figure 7 shows the flows of COVID status verification.

Fig. 7

COVID status verification

The proposed blockchain framework adds a protection layer and helps people from the virus while maintaining their daily business activities. The proposed framework helps the offices, shops, businesses, educational institutes, and law enforcement agencies check the people based on Blockchain’s available data. With our proposed framework, individuals can also verify each other through the smartphone’s Bluetooth interface as they engage in day-to-day activities. Let us take an example here: Alice wants Bob, a carpenter, to work at her premises. Therefore, our proposed framework allows both Alice and bob to know their COVID status and generate an e-pass before interacting with each other. The steps involved in exchanging credentials between both parties, i.e., shown in Fig. 6 above, and described as follows:

The Block Miner arranges transactions as they are received from different sources. Hence, there are multiple transactions obtained from different sources shuffled together. This makes it complex to link the available data to any transaction in its origin.

As the testing centers and hospitals keep in the Hash of public key in the transaction, any beneficiaries cannot trace back any information to any random person because it could not map a provided hashed public key to its matching public key.

When any person has to provide his/her identification to any other person, they can use Bluetooth interface from few feet away. If Alice has to present identity to Bob, Alice sends her public key KPbAlice through the interface of Bluetooth to Bob. Bob searches through the ledger for any transaction against Hf(KPbAlice). If Bob searches any transaction against Hash, the only stuff that Bob needs to find out is the COVID status of Alice because the rest of all the epidemiological information has the private key encryption from the Central Authority. This way, Bob is not able to see any details about Alice except the COVID status.

The central authority cannot link any data with any individual because the central authority has access to epidemiological data via its key.

Central authority cannot trace back transactions for the epidemiological information of an individual. However, they can collect the individual’s public key via Bluetooth interface and collect the epidemiological information via Blockchain (with the Hash of this public key). This can help the central authority to perform mass surveillance of citizens.

Alert mechanism

The proposed framework helps authorities to declare a section like a green/orange/red zone. Then, the GPS coordinates, the radius of a zone, date, and time are added in the Blockchain transaction. As the Blockchain is available publicly, the public can avail of data promptly via the dispersed ledger. With this, if a person is about to enter a red zone, he/she is alerted through the app.

Stakeholder’s incentives

The accomplishment of a structure this way requires cooperation from each person of any state. Be that as it may, it is hard to acknowledge such a contribution. Aside from the more extensive social objective of restricting infection, there must be a detectable impetus for the person. To understand how distinct areas of the public are getting profit from such structure, users of such system are categorized in accompanying gatherings, in light of their similitude of intrigue.

Category I: Individuals.

Category II: Business houses, offices, shops, Institutes, etc.

Category III: Testing Centre, Hospitals, Laboratories, police personals.

Category IV: Authority.

Class I contains two sorts of people: (a) a person whose COVID status is “+ive” or is “In Quarantine (IQ)” (b) a person whose COVID status is “Out of Quarantine (OQ)”, or a person who never had any side effects and never meet a contaminated individual. At the same time, individuals of the principal kind might want to see the difference in their status (the state from “+ive” to “-ive”, “-ive” to “intelligence level” and “level of intelligence” to “OQ”.) in the open record, individuals of the following kind might want to continue with their everyday work with insignificant limitations while staying shielded from the disease. On the off chance that the power, shops, markets, workplaces, organizations, and forth permit authorization of their offices just to those discovered protected, at that point, the establishment of the COVIDSafeApp empowers individuals to utilize their smartphone as a computerized pass to approach these offices.

Category II people might want to continue with their everyday business while dealing with their own and other’s security. By checking each person’s COVID status at section focuses, these people have the option to offer a safe condition to their workers and customers.

People in Category III perform the exchanges for the Blockchain by performing a clinical test on the people. Given the past status of an individual (state “+ive”), a new exchange with status (state “level of intelligence” or “OQ”) might be made in his subsequent visit. This classification is fruitful to the legislature and the general public.

Category IV has social commitments to ensure the general public by avoiding the spread of the infection. These people are liable for setting up such a framework and keeping it running. They have the option to authorize severe isolation for individuals recorded as “+ive” or “intelligence level” in the Blockchain. Individuals without a COVIDSafeApp, may not be permitted to work or move unreservedly. To authorize such limitations, a few nations have embraced the procedure of stepping the hand of isolated individuals. Be that as it may, stepping has its confinements like given below:

Stamp imprints may blur off earlier than the finish of isolation time.

Stamp imprints may persevere significantly after the isolation time is finished.

Individuals with stamp imprints may need to confront social shame.

Simulations results

The proposed framework simulation is carried out in the MATLAB framework. The primary purpose of this research is to design a system that individuals predict their COVID status after entering symptoms in a Blockchain-based app, so we have organized two systems as a proposed model. Firstly, we use the Artificial neuro-fuzzy inference system (ANFIS) to predict COVID Status and KNN to improve the accuracy rate. Secondly, we use a real-time numerical dataset consist of COVID-19 symptoms for KNN. KNN consists of Ensemble KNN, Cousine KNN, and Fine KNN. This dataset consists of COVID symptoms; based on these symptoms, our system predicts the accuracy rate after training and testing with all types mentioned earlier. For this purpose, the dataset is split into training and testing folds. The proposed system predicts covid status based on all given symptoms, and KNN enhances the accuracy rate with ensemble KNN. On the other hand, for our proposed ANFIS system, the dataset is divided into two partitions 80% for training and 20% for testing. Here Sugeno model is applied because the given dataset is numerical. It consists of six input parameters and only one crisp output yes/no. The trained framework predicts either the person is affected or not.

ANFIS simulation

In our scenario, six input parameters, age, cough, fever, diarrhea, flu, and headache, are taken. An individual can quickly check the COVID status after using the blockchain-based app after entering those symptoms that appear in a person. Accordingly, it can be analyzed that a person is affected or not. While using Fuzzy more than one input is taken, and there is single crisp output in the form of Yes or No.

Figure 8 represents the ANFIS Sugeno model with six input parameters and a crisp output and Fig. 9 presents the ANFIS model structure. Figure 10 demonstrate the surfaces view of ANFIS model.

Fig. 8

ANFIS Sugeno Model

Fig. 9

ANFIS Model structure

Fig. 10

Surface view

Rules are defined based on given symptoms. As we know, a system is not completely perfect. The proposed training model consists of 10 epochs on the x-axis of the graph as shown in Fig. 11. Here total testing error is 0.58% as shown in Fig. 12. We can predict that our system performance is good.

Fig. 11

Training plot

Fig. 12

Testing plot

KNN simulation

We use the KNN algorithm for data classification on the dataset. The dataset is numerical and based on COVID symptoms to predict the affected or non-affected person. The KNN primary purpose is to increase the accuracy rate after training the dataset on KNN algorithms. The dataset consists of 415 rows and 16 columns. Here we choose the KNN algorithm for implementation and import our dataset on its all types. First, however, KNN is divided into fine KNN, Cousine KNN, and ensemble KNN. After training the dataset on all KNN algorithms, we conclude that ensemble KNN has achieved the best accuracy rate. The total accuracy rate is 95.9%. It has been observed that ensemble KNN achieves the highest accuracy rate. Here total accuracy is 95.9%. Figure 13 represents the ROC curve graph for our proposed framework.

Fig. 13

ROC curve graph

The confusion matrix in Fig. 14 consists of the true positive rate and the false positive rate. There are two types of classes one is true class, and the other is predicted, class. We can calculate the precision, accuracy rate, correct classification, and misclassification through this true and false positive rate. The confusion matrix shows that all parameters are predicted accurately.

Fig. 14

Confusion matrix of the framework

Discussion

Anonymity is there for other people, but anonymity is very rare in authority and government. To get people’s trust and increase the application’s adaptability, assurance of a person’s anonymity from authority is also precious. In COVIDChain, both sides are considered. In COVIDChain, a person can get knowledge about the COVID status of any other person. Provided that authority does have accessibility to epidemiological data, trace-out of a person is not possible. In many works, epidemiological data is not gathered, but the possibility of such an app is only there if authority makes a big-sized investment and causes mobilization of public resources. In its return, it would be wanted if new information is calculated regarding the design of the coronavirus’s spread. Consequently, plans for the restriction of the spread of the virus can be made. That is why epidemiological data must be gathered (ensuring the anonymity of people). In COVIDChain, we have the facility of gathering epidemiological data that only authorities can access. The general public cannot gain access to that data because it is in an encrypted form. These applications generally use GPS and Bluetooth for connectivity other than internet connectivity. These two technologies are essential in sending and receiving data about the coronavirus spread; it is also crucial that communicated data does not put a person’s anonymity at risk. Furthermore, no one should have the ability to transfer incorrect information, which can be misleading and faking to be somebody else. Therefore, COVIDChain has a suitable structure that can be used for a person’s authentication. For this, Blockchain is never loaded with GPS information that relates to a person. However, only the data which is part of a containment zone is saved.

As shown in the table, the spotlight of much of the work in this section is on tracing people who may have been inside of the zone of a coronavirus-infected person. This kind of work is of great value as it can play its part in identifying people at risk and should be put into quarantine or advised to undergo a test for the coronavirus. However, further to this contact tracing, it is crucial at the same level to make sure that a person who is quarantined is not putting other people in danger by roaming around. The COVIDchain framework permits persons to check other people’s coronavirus status, similar to a digital pass. Thus, it can help control people quarantined from roaming around in public places.

In many works, projected information regarding the corona virus’s spread is saved in a centralized place under one authority controlling it. To have this kind of setup, it is tough to gain people’s confidence and support for their privacy and safety of the data they share. It is challenging to assure the public that their data be kept safe and not be used for any other purpose after the COVID crisis end. That is why the form and related part of data must be publicly shared, open for scrutinizing and audit. Taking such a step help gain people’s support and further assists different parts of society in being well informed with trusted data and is open to their businesses. Blockchain technology is used in COVID-Chain for record-keeping. As a result, a similar copy of the ledger is kept updated in various areas with reliable information that all societies can access.

Conclusion

To restrict the fast spreading of COVID-19, a few advanced smartphone applications have been developed. A significant part of the existing studies is centered around contact tracing of individuals who may have been in the closeness of a COVID-afflicted person. In any case, in the current situation, when the world is proceeding with lockdowns that have carried the economy of almost every country to the corner, there is a requirement to investigate specialized approaches to encourage both physical and social isolation and financial exercises to move-ins. This paper proposed a Blockchain-based framework that preserves patients’ anonymity while tracing their contacts using a smartphone application to interact with the proposed blockchain framework for contact tracking using Bluetooth. The proposed framework helps people to perform business activities with a controlled mechanism that keeps them safe from infected and exposed people. This application quickly checks their COVID status after entering their symptoms and easily observes (based on given symptoms) either this person is affected or not. As a result, our proposed fuzzy system predicts the COVID status based on symptoms (either individual is affected or not).