Program Checking with Certificates: Separating Correctness-Critical Code

We introduce program checking with certificates by extending the traditional notion of black-box program checking. Moreover, we establish program checking with certificates as a safety-scalable and practical method to ensure the correctness of real-scale applications. We motivate our extension of program checking with concepts of computational complexity theory and show its practical implication on the implementation and verification of checkers. Furthermore, we present an iterative method to construct checkers which is able to deal with the practically relevant problem of incomplete or missing specifications of software. In our case study, we have considered compilers and their generators, in particular code generators based on rewrite systems.