一种基于完整性度量架构的数据封装方法

封装存储是可信计算平台的一项重要功能,它能将数据的加密存储与平台状态结合起来,提供了更强的安全存储保证.但现代操作系统结构越来越复杂,各种启动项的加载顺序也相对随机;平台配置的频繁改变、软件更新及系统补丁等都限制了封装存储的应用.而操作系统级的完整性度量架构(IMA)能将信任链扩展到整个计算平台,为封装存储提供了支持.为此,基于IMA提出一种新的数据封装方法,采用相对固定的标准状态来封装,结合易变IMA度量列表和结果以及经过签名的名单策略来评估平台状态,解决了操作系统复杂性带来的配置寄存器(PCR)的值不确定性和软件更新及系统补丁带来的频繁封装问题.

A Data Sealing Approach Based on Integrity Measurement Architecture

As an important capability of trusted computing platform,sealing can provide strong data storage security by combining data’s encryption with the platform configuration,by which data can only be unsealed under specific configurations.However,sealing operation is hard to use for the complexity of modern OS,the randomness of the loading order of the booting components,the frequently changing configuration,software update and patches.IMA(integrity measurement architecture) implemented in operating system could measure the dynamic configurations and extend them to the trust chain of the whole trusted platform,and then support the data sealing.Therefore,a new approach to data sealing based on IMA is proposed here,which seals data to a relatively fixed configuration in PCR0—PCR7(Platform Configuration Register) and then applies a list policy(black list policy or white list policy) to the measurement list(ML) in IMA for the variable configuration in PCR10 to determine whether the unseal operation can be performed.Finally,a prototype system "TPM Master" implemented in Linux is given and its performance and security analysis are both evaluated.The results show that the proposed approach could solve the issue of the PCR value varying with the OS complexity and make updating process much more flexible by the list policy,without re-sealing the original data.