Robust Combiner for Obfuscators

Practical software hardening schemes are heuristic and are not proven to be secure. One technique to enhance security is robust combiners. An algorithm C is a robust combiner for speci cation S, e.g., privacy, if for any two implementations X and Y , of a cryptographic scheme, the combined scheme C(X, Y ) satis es S provided either X or Y satisfy S. We present the rst robust combiner for software hardening, speci cally for obfuscation [2]. Obfuscators are software hardening techniques that are employed to protect execution of programs in remote, hostile environment. Obfuscators protect the code (and secret data) of the program that is sent to the remote host for execution. Robust combiners are particularly important for software hardening, where there is no standard whose security is established. In addition, robust combiners for software hardening are interesting from software engineering perspective since they introduce new techniques of software only fault tolerance.