Software watermarking using fixed size encoding and random dummy method insertion

Abstract

Recently, the rise of software piracy has become rampant and a major concern among software developers. The global software industry lost about USD 50 billion in 2008. One of the techniques that can be used to discourage piracy is watermarking, by embedding developer’s watermark into software which can later be extracted to prove ownership. During the last few years, different algorithms were produced and developed to hide the watermark inside software. This study analyzes software watermarking algorithms that exist in the literature and then identified a dummy method algorithm is suitable for watermarking. In addition, this study enhances dummy method insertion technique in embedding and recognizing the watermark in Java class files. The enhancement includes fixed size encoding scheme and random dummy method insertion. The proposed fixed size encoding scheme used hash function that can produce a fixed size watermark bit sequences. Random dummy method insertion selects a dummy method at random from a collection of dummy methods. Finally, this study analyzes the enhancement of dummy method insertion technique using two different measures, namely data-rate and resilience of the watermarking algorithm. In term of data rate, the results show that encoded watermark for proposed encoding scheme is always fixed even though size of watermark character is increased. In term of resilience, experimental results show no similarity between class files and thus survived from collusion attack compared to previous method.