Answer following questions.

$[6+4=10$ marks$]$

A cloud service provider $($CSP$)$ is designing a multi$-$tenant cloud infrastructure to host various services for different clients. As part of their security architecture, they need to ensure that their system adheres to the principles of "Economy of mechanism," "Complete mediation," "Open design," and "Least common mechanism."

The CSP is planning to implement an access control system to manage and monitor access to resources within the cloud environment. This system will handle authentication, authorization, and logging of user activities. Each client has its own set of resources, and access to these resources must be strictly controlled to prevent unauthorized access and ensure data privacy.

$($a$)$ Draw a detailed architecture diagram of the proposed access control system for the CSP$.$ Clearly label the components and indicate how they interact with each other.

$($b$)$ Ensure that your design incorporates mechanisms to support each of the four principles mentioned above.