# Security, Privacy, and Reliability in Digital Healthcare Systems Using Blockchain  
[PERSON]  
1 Department of Software Systems and Cyber-security, School of IT, Monash University,  
Subang Jaya 47500, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
2 Advanced Communication Engineering (ACE) Centre of Excellence, Universiti Malaysia Perlis,  
Kangar 01000, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
4 Department of Software Systems and Security, School of IT, Monash University,  
Subang Jaya 47500, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
5 Department of Software Systems and Cyber-Security, School of IT, Monash University,  
Clayton, VIC 3168, Australia; [EMAIL_ADDRESS]  
[PERSON]  
6 Department of Computer Science, College of Computers and Information Technology, Taif University,  
P.O. Box 11099, Taif 21944, Saudi Arabia 6  
[PERSON]  
7 Department of Computer Engineering, Ajou University, Suwon 16499, Korea 7  
Moreover, security and privacy challenges are crucial for blockchain-based models, especially systems that use the integration of healthcare systems. Security breaches consist of denial-of-service (DoS), structured query language (SQL) injection, spoofing, eavesdropping, and replay attacks, which are challenging for IoT-based systems. Such attacks affect security applications and their authorization, authenticity, and privacy. Therefore, it is very important to address these issues and to provide a novel design framework that can provide security to IoT devices that leverage blockchain applications. It is evident that weak security at any node can lead to access to patient health records. An electronic health record (\(EHR\)) is regarded as the most important and sensitive type of data because it consists of a lot of sensitive information related to patients and diagnoses. However, the advancement and progress in digital healthcare systems has caused \(EHR\) data to become more vulnerable to breaches [5]; hence, security and privacy must play an important role in the case of decentralization and trust [6]. However, a very important aspect of IoT may provide more security and applications to diverse users [7]. Due to the ease of access to the internet and the increase in smart communication among people, objects, data, and processes, the exponential growth in the number of connected devices throughout the globe resulted in billions being recorded in the year 2020 [8]. Therefore, the security challenges of IoT applications are the basic requirements for dealing with such issues. Consequently, there has been an improvement in their intricacies, as the great complexity of devices provides less security in the performance of access control. Access control is the basic security tool for \(EHR\) data from any source. Therefore, it is compulsory to design access control policies for \(EHR\) and \(PHR\)[9]. A blockchain-based digital healthcare framework, which is also called Hyperledger Fabric, is used for the development of patient health record (\(PHR\)) systems. Security, privacy, and cross-domain authorization are factors that influence patient health records around the world. According to the security breach level index, every single day, million of records are stolen online [10]. These issues need to be explored by researchers in order to investigate the security and privacy challenges related to the use of blockchain for \(PHR\). In a digital healthcare system, a cross-domain organization approach can provide facilities to clinicians and patients for accessing data that are distributed among different domains. On the other hand, accessing data through a cross-domain organization requires more security and flexible authorization policies. A policy defines rules and strict conditions for the attributes of participants and data. Moreover, data can be encrypted by using cryptographic techniques. In the literature, the encryption techniques used by the researchers are based on ring signatures and group signatures.