Key evolution-based tamper resistance: A subgroup extension

Abstract

The number and magnitude of hostile attacks against software has drastically increased. One class of attacks of particular concern to the software industry is tampering to circumvent protection technologies such as license checks. A variety of hardware- and software-base techniques have been developed to address the issue. These include, but are not limited to, dongles, smartcards, and code obfuscation. In this paper we examine two previously proposed software-based tamper resistance techniques which are both based on the same key evolution mechanism: Event Log-Based and Branch-Based tamper resistance. As proposed the techniques offer many advantages over other software-based algorithms, however, they still suffer from a common limitation. Through our analysis we identify this limitation and propose an extension to the schemes which improves the overall strength. Copyright 2007 ACM.