Abstract In this paper we analyze the effectiveness of two different software watermarking algorithms. The first is an algorithm proposed by Akito Monden et al. and the second an algorithm proposed by Robert L. Davidson and Nathan Myhrvold of the Microsoft Corporation. We have implemented these techniques within the SANDMARK framework, a system designed to study the effectiveness of software protection algorithms on Java bytecode. To the best of our knowledge this is the first implementation and empirical evaluation of these algorithms with respect to a set of properties such as bit‐rate, stealth, and resilience to attack. We demonstrate through the use of the SANDMARK framework that both of these algorithms have a high bit‐rate but are unstealthy and easy to attack. Copyright © 2005 John Wiley & Sons, Ltd.

Dynamic detection of program invariants is emerging as an important research area with many challenging problems. Generating suitable test cases that support accurate detection of program invariants is crucial to the dynamic approach of program invariant detection. In this paper, we propose a new structural coverage criterion called invariant-coverage criterion for dynamic detection of program invariants. We also show how the invariant-coverage criterion can be used to improve the accuracy of dynamically detected invariants. We first used the Daikon tool to report likely program invariants using the branch coverage and all definition-use pair coverage test suites for several programs. We then generated invariant-coverage suites for these likely invariants. When Daikon was run with the invariant-coverage suites, several spurious invariants reported earlier by the branch coverage and definition-use pair coverage test suites were removed from the reported invariants. Our approach also produced more meaningful invariants than randomly generated test suites.