## 2 Literature Review
### Smart Healthcare
#### 2.5.2 Countermeasures  
The most complicated difficulties in smart healthcare systems are ensuring patient health data confidentiality and privacy. This paper [109] explores health data confidentiality, MIoT healthcare security concerns, and the rules and regulations involved in establishing a smart healthcare system. It also describes the many prevalent principles and assaults exposed to corporate digital assets and patients' health information, as well as the necessary solutions for overcoming the present obstacles, such as a cryptographic function and a communication protocol. For example, this work [88] provides a complete overview of possible authentication risks and attacks on IoT healthcare devices in the Smart healthcare area. Furthermore, utilizing a hybrid cryptographic technique, the authors of [110] established a secure cloud storage solution for healthcare data. A symmetric algorithm encrypts data, while an asymmetric algorithm encrypts keys. The performance and security of the proposed approach were measured and compared to a well-known current technology. Because it is based on a modular exponentiation process, the RSA method often performs poorly. As a result, the authors used the Montgomery modular multiplication technique to enhance the RSA implementation. Blowfish encryption is used when storing health-related data in the cloud, and keys are handled using the improved RSA technique. This hybrid technique provided advantages such as quick encryption, large prime numbers for essential creation, and efficient key management. The simulation results reveal that the suggested hybrid technique's encryption and decryption time is faster than other approaches examined for comparison. Important points to discuss when exchanging information in a smart health system dealing with critical patient data are communicating across institutions and safeguarding patients' private data. This work [111] proposes a method for saving image-type data using visual cryptography and distributing the data utilizing corrective sharing using practitioners' passwords. However, if penetrated, the underlying infrastructure might result in private data leaks and the destruction of healthcare records dependent on the control commands supplied by the attacker. The authors of this paper [112] concentrate on several degrees of security associated with the storage and transmission of healthcare information. Furthermore, they test some of the suggested approach's relevant characteristics using the access control policy testing tool to establish its practicality and examine the state of the art in the subject. However, because the present record management system cannot fully handle privacy and integrity, the health sectors nowadays use blockchain technology to store health data in a more safe, confident and decentralized manner. This study [113] offers a blockchain architecture for electronic health records to safeguard private data based on the elliptic curve cryptography algorithm. In parallel, this study [114] proposes a realistic solution based on the unique characteristics of blockchain, where the distributed ledger technology is thought to be unbackable. The authors created a blockchain model to safeguard data security and privacy, assure data provenance, and give patients total control over their health information using the smart contract feature, a programmable self-executing protocol operating on a blockchain. This concept delivers a patient-centric procedure by customizing data segmentation and creating permitted lists for physicians to access their data. It assesses the model's feasibility, stability, security, and robustness. In addition, this article [115] offers a permission Ethereum blockchain that connects hospitals and patients all over the globe. The proposed system employs symmetric and asymmetric key encryption to enable safe storage and selective access to records. It gives patients total control over their health information and allows them to grant or deny access to their records to a hospital.