Separating information protection from resource management

Securing information in a computer system is becoming an intractable problem. Exacerbating the situation is the current paradigm of trusting an operating system for both security and resource management. One solution to this problem is to separate the role of protecting information from managing resources.;This thesis studies the design and implementation of a system architecture called Software-Privacy Preserving Platform (SP3). 5P3 creates a new layer that is more privileged than the operating system and responsible for providing information secrecy to user applications. SP3 provides page-granular memory secrecy protection by augmenting memory paging and interrupt mechanisms of a computer system in such a way that physical memory pages for user applications are rendered encrypted to the operating system. The resulting 5P3 system therefore provides secrecy protection for the information contained in the memory of user applications. SP3 is implemented by modifying a hypervisor, which efficiently emulates the augmented semantics of paging and interrupt mechanism introduced by 5P3. The modified hypervisor employs a couple of optimization techniques to reduce the number of costly page-wide block cipher operations. In the page-frame replication technique, the hypervisor internally keeps both encrypted and decrypted images of a page and relies on shadow page table redirection to map the correct page. In the lazy synchronization technique, the needed synchronization between the replicated images of the page is deferred as long as possible so that the synchronization happens not when an image is modified, but when the other image is actually accessed. This thesis further explores the challenges and solutions in the new programming environment introduced by SP3. This thesis also presents an SP3-based digital rights-management solution that can protect both the copy-protected multimedia contents and a trusted multimedia player program without limiting the end-users' freedom.;In conclusion, this thesis demonstrates the feasibility of separating information protection from resource management in systems software. This separation greatly reduces the size and complexity of the trusted part for information protection, resulting in a more resilient system that can tolerate a compromise in the operating system.