Protecting Java Source Code Beyond Obfuscation

Java class files are easy to reverse-engineer. The very properties that enable Java applications to run anywhere make reverse translation straightforward.

There are a number of Java decompilers on the market that produce amazingly readable source code. Any person of ordinary skills in programming can download a Java decompiler, run your application through it and read the source code almost as if it was open source.


An obfuscator can make the decompiled code less comprehensible. However, name obfuscation may cause reflection and JNI failures, whereas extensive control flow obfuscation negatively impacts performance and may provoke a VerifyError. To make things worse, these problems only manifest themselves when the respective class is actually loaded at application run time, and thus may slip through the QA process. And reverse engineering of an equivalent C++ program passed through an optimizing compiler would still be more difficult.

Strengthening Protection with Protector4J

Protector4J can help to protect your java source code by encrypting the classes, it made a custom native ClassLoader by modifying the JVM. The Java classes are encrypted by AES and decrypted in the native ClassLoader. And it also introduces some mechanisms to improve the difficulty of cracking.

Encrypting your code protects your intellectual property and substantially improves the security of your Applications. It makes IP theft, code tampering, and discovery of security vulnerabilities involve an expensive reverse engineering effort, whereas practically anyone can download and run a free Java decompiler.

Protector4J can also help to to create the executable wrapper of your Java App for Windows, Linux, macOS