Research On Secure Operating System Based On Trusted Computing

The compromising of the secure OS (operation system), one of the mainstream security technologies, could threaten the safety of the entire system. Therefore, it is crucial to have relatively low-level security supports for the secure OS itself. Among all the threats of being compromised, the compromising on the integrity of the secure OS happens most frequently. The integrity of the secure OS consists of the integrity of the sensitive data, the integrity of the secure policies, the integrity of the labels, and the integrity of the reference monitors. Existing integrity protection techniques provided by the secure OS either have much vulnerability or use inadequately strong security assumptions. It is desirable to have a more secure integrity protection technique for the secure OS.This thesis leverages the trusted computing technique to enforce the security of the OS. The shortages of protection methods of the integrity are analyzed. By using trusted computing technique, this thesis proposes a dynamic measurement method which realizes the trusted verification of the OS state. A policy-label protection mechanism is proposed to address the safety problem of the security labels. This thesis also presents a method to extend the edge of the control area of the secure OS by adopting trusted computing techniques such as remote attestation and sealed storage. The main contributions of this thesis are listed as follows:1. Dynamic measurement based on trusted computing. This thesis proposes a memory-based dynamic measurement method that solves the TOC-TOU (time of check with time of use) problem seen in the existing static file-system-based measurement method. The improvement on the dynamic measurement based on the algorithm analysis is also proposed to efficiency as well as the usability of the measurement under complicated environment.2. Trusted computing based Policy-label protection. This thesis proposes TLPA (TPM-based Label Protection Architecture) to protect the easily compromised security policies and labels in the access control system. By using mechanisms of integrity measurement, encrypt file system, etc., security labels are protected in the trust zone which enhances the safety of the access control system as well as the secure OS.3. Trusted virtual edge. This thesis proposes a method to extend the control area of secure OS by using a form of trusted virtual edge. In this approach, the dominating area of a secure OS is not constrained by its physical boundary. The data managed by the secure OS is thereby protected no matter it is stored locally or distributed to other physical machine.In summary, this thesis enforces the security and enlarges the dominating area of secure OS by using trusted computing technique. The researches proposed by this thesis can not only support the secure OS research but also be used a reference of trusted computing-based work.