A Trusted Computing-Based Security Architecture for Policy-Label Protection

Policies and labels are the most important parts in access control technique. Labels present some security properties of the subject and the object, meanwhile policies present some logical algorithms based on the security properties carried by labels. The enforcement of access control system can be mainly decided by these two factors. Nowadays most security systems can give a well protection to the policies, but almost none of them have systemic and well-defined methods to protect labels. They just believe that the operation system can do the work itself. The lack of label protection leads to a result that even the policies are secure and well-defined, malwares can still do harms to the system by tempering the labels. Then the system is unsafe in the end. An architecture mainly to protect the security labels in the system by using TPM (trusted computing module) chip is proposed. TPM chip is a kind of hardware provided by TCG (Trusted Computing Group). It can be used to build a TCB (trusted computing base) in a secure system. But the TCB here is too small to hold labels. By using some mechanisms such as encrypting file system and integrity measurement, we extend the edge of the TPM chip's control area and keep the labels into this area in order to enhance the safety of access control system. Implementation of a prototype system on the Linux OS is given and the experiments show the security and efficiency of our implementation.