# Challenges and Solution Directions of Microservice Architectures: A Systematic Literature Review
## 5 Identified Challenges and Solution Directions
### RQ2. What Are the Identified Solution Directions?
#### 5.2.7 Security  
Study [AJ] focuses on the limitations of access control technologies in the microservice environment. This paper suggests an access control optimization model based on role-based access control (RBAC). This model enhances the attribute-based encryption (ABE) model being one of the most common cryptographic mechanisms, in which existing RBAC users can directly access the ABE encrypted data in microservices. It has several advantages compared to ABE, which includes improving the expression ability of access policies, the security and operational efficiency of microservices, and reducing the computational cost.  
Study [V] investigates the microservices security topic and tries to identify the taxonomy of security issues. While making this research, Docker Swarm and Netflix security decisions are also investigated. This paper claims that microservice security requires a layered security solution consisting of hardware, virtualization, cloud, communication, application, and orchestration. In this paper, a prototype framework for microservice security is described and a case study is conducted. The case study result shows the performance overhead of the security is around 11%.  
Study [D] focuses on two problems of microservice security. First, network complexity complicates monitoring the security. Second, due to the trust among microservices, if any microservice fails, it may affect the entire application. In this paper, the authors propose a design for security-as-a-service for microservices-based cloud applications and they implement a flexible monitoring and policy enforcement infrastructure for network traffic by adding a new application programming interface (API) primitive FlowTap for the network hypervisor. Effectiveness analysis results show that the proposed solution is able to tackle various monitoring scenarios.  
Study [AC] addresses the problems of authentication and authorization in the 5G platform. The authors come up with a solution based on specifically identity and access control of microservices. The proposed solution has been implemented in the network function virtualization (NFV) based platform called SONATA. It encourages using well-known techniques and simple designs for identity and access control and favors role-based access control.  
Study [T] focuses on the problems of the authenticity and confidentiality of microservice calls. This paper criticizes the HTTP-based approach used for microservice and API calls and transport layer security (TLS), providing only link-level channel security. In order to prevent these security problems, this paper comes up with a solution consisting of authentication with password and key pair and decentralized role-based authorization.  
Study [BT] points out that the security of access control becomes challenging as the system grows because it causes more access points to be handled for security. The authors propose an extended version of role-based access control (RBAC) called hierarchical trust RBAC. This model enables security managers to detect unauthorized access to sensitive information and identify verification. They also conducted a case study to show the feasibility of their model. Case study results showed that it provides faster and more flexible access to sensitive information.  
In summary, secure microservices are tightly dependent on our MSA design. Software architects should design MSA by taking into account the security concern since it might be tough work to provide a secure system later. These studies propose solutions to identified problems, but there is no study proposing a model about how to design MSA to ensure security.