ChecKing Information Flow on Output Channel with Reachability Analysis of Pushdown System
基于下推系统可达性分析的输出信道信息流检测

We proposed an approach for analyzing information-flow security of imperative language with output channels. The program is abstracted with pushdown system, which is then self-composed in order to adapt noninterference as a safety property. The output operations in the two relevant runs are respectively modeled as storing and matching procedure by pushdown rules. Then the termination-insensitive noninterference is verified by a reachability analysis of illegal-flow state. A variation of this approach can deal with program containing divergent run. An upper-bound regression algorithm was proposed to find the maximum upper-bound in order to trigger coercive termination of divergent run. The experimental results show that the approach is more precise and efficient than existing work.