An Approach to Data Sealing Based on Trusted Virtualization Platform

In trusted computing platform, one of the most important features is the sealing functionality which can provide strong data security by combining datas encryption storage with the platform configuration. Data is sealed to the platform configuration, and the sealed data can only be unsealed and used normally when the platform configuration at unsealing is the same as it at sealing. However, the platform configuration changes frequently with hardware exchanges, software updates and system patches, which restricts the use of the sealing functionality heavily. Aiming at this limitation, the current solutions are improved to support configuration updates based on hardware or software, but they just consider the usage of sealed data on two platforms with different configurations and the same property, which even have no implementation at all. Furthermore, the trusted platform module (TPM) has heavy burden and the efficiency is very poor in these solutions. In order to solve the problem, an approach about data sealing storage based on trusted virtualization platform is presented, which introduces the concept of virtual PCR (vPCR) and security property, and utilizes the TPM to seal data with the security property of the system. Virtual machines configurations are stored in vPCRs, and their corresponding security properties will be dynamically stored into the PCR by turns before sealing or unsealing starts. The security properties are classified by the security levels. The sealing and unsealing operation must be performed according to the rule that sealed data can be successfully unsealed only if the security level of the security property when unsealing is not less than the security level of the security property when sealing. The approach can adapt to platform configurations frequent changes, and also can protect datas security in many virtual machines without being effected by configurations changes. The operation of the approach is simple. Through experiment, it is shown that the burden of the TPM is light and there is no evident decrease in efficiency compared with the former approach.