A Digital Watermarking Method for Java Class Files

The aim of this paper is to easily identify an illegal Java program containing a stolen class file. This paper proposes a method for encoding and decoding a digital watermark, such as a program developer’s copyright notation, into/from Java class files. Characteristics of the proposed method are: Execution efficiency of the target program is not reduced by watermark encoding, watermark decoding can be automated, and, an overwriting attack is prevented even if a watermark encoding tool is distributed in the public. The result of the experiment to evaluate our method showed that all the watermarks embedded in class files survived an obfuscator attack, and also showed that more than half of watermarks survived a decompile-recompile attack.