# Privacy-Aware Cloud Architecture for Collaborative Use of Patients' Health Information
## 1 Introduction
### Cloud Computing in Healthcare  
Cloud computing appears to be the dreamed-of vision of the healthcare industry; it refers to means of storing and accessing data and programs over the Internet instead of the computer's hard drive [23]. Cloud computing meets the need for healthcare information sharing directly with various healthcare-related parties over the Internet, regardless of their location or the amount of data being shared. The use of cloud computing in the healthcare sector has increasingly been highlighted as having great potential for facilitating data-driven innovations [24]. It offers functionality for managing information in a distributed, ubiquitous, and on-demand network with access to a shared pool of configurable computing resources [25]. Resources in cloud computing can be rapidly provisioned and released with minimal management effort, supporting several platforms, systems, and applications [26]. Due to resource elasticity and lower operational costs, cloud computing is appealing for healthcare. This allows novel healthcare development, delivery, and use [27; 28]. Due to the rapidly growing applications of e-health systems, which have been hampered by the conventional healthcare information system's lack of interoperability, cloud computing is found to be the best option for the global e-healthcare systems that are in place [29]. However, the adoption of cloud computing in the healthcare domain faces privacy-related challenges [30; 31]. Such challenges are caused by the fact that medical data and information that are classified as confidential are stored on cloud servers, a virtual world where information can be easily hacked [32]. Storing data on the cloud is a major concern for consumers, preventing healthcare cloud computing adoption [31]. The authors in [33] conducted a review of security and privacy-preserving challenges in e-health solutions. The review included various privacy-preserving approaches to ensure the privacy and security of electronic health records (EHRs) in the cloud. The review revealed a number of crucial privacy challenges that must be addressed before obtaining the full potential of cloud computing in the healthcare domain. The authors wrote \"Studies must focus on efficient, comprehensive security mechanisms for EHR and also explore techniques to maintain the integrity and confidentiality of patients' information\". Cloud computing's biggest drawback in healthcare is third-party data storage [31]. Although data are usually encrypted, the owners require control over their data to perform operations such as updating records. In the normal process, data transferred to the cloud go through traditional encryption methods for security reasons; however, the data holder needs to decrypt the data whenever an operation is required on it. The data user provides the private key to the cloud provider to decrypt the data in order to execute any required calculations. The decryption of the data on the cloud provider's side causes privacy and confidentiality issues. Moreover, a patient's record may include information that might not always be needed for all different instances of medical treatments; for example, a patient who has a certain sexual disease might not want a practitioner at an emergency practice to access and read information related to such a disease when it is not needed in that particular treatment instance, therefore, accessing such unneeded information may also cause a breach of the patient's privacy. Thus, to integrate cloud computing into healthcare while protecting patient privacy, a design must overcome these privacy issues. This paper proposes a cloud architecture design for storing and sharing patients' health data with respect to privacy and confidentiality.