An Instruction Folding Method to Prevent Reverse Engineering in Java Platform

To improve tamper resistance of programs against illegal modification, this paper proposes instruction folding applicable to Java platform. In the proposed method, at first, similar methods are selected in a Java program. Next, these methods are merged into one method and diffs among these methods are stored in the program. Then, at runtime, when one of the merged methods is executed, diffs are restored by self-modification, which is realized by the Java instrumentation mechanism. The proposed method is resilient against tampering of folded method. Even if an adversary modifies the folded method, the program goes crash because the method is repeatedly modified at runtime.