Zelix KlassMaster - Documentation

Compatibility

What do you need to run Zelix KlassMaster™?

Zelix KlassMaster™ is written entirely in Java 8 (i.e. JDK 1.8) and technically should run on any platform that supports a Java 8 or better Virtual Machine. However, note that Zelix KlassMaster™ version 10 or better requires a recent version of a Java 8 JVM or better to run. If you use an Oracle JVM earlier than 1.8.0_152 then you may get a JVM crash due to HotSpot bugs.

More generally, differences in the file systems and GUIs can also cause problems. Further, Zelix KlassMaster's flow obfuscation technology can expose bugs in some Just in Time (JIT) compilers.

Zelix KlassMaster™ has been tested on:
  • Windows 10™ 64bit and Windows 8.1™ 64bit using
    • Oracle build "1.8.0_221" Java HotSpot(TM) 64-Bit Server VM (build 25.221-b11, mixed mode)
    • Oracle build "11.0.4" 2019-07-16 LTS Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.4+10-LTS, mixed mode)
    • Oracle build "12.0.2" 2019-07-16 Java HotSpot(TM) 64-Bit Server VM (build 12.0.2+10, mixed mode, sharing)
    • Openjdk build "1.8.0_222" OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.222-b10, mixed mode)
    • Openjdk build "11.0.4" 2019-07-16 OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.4+11, mixed mode)
    • Openjdk build "12.0.2" 2019-07-16 OpenJDK 64-Bit Server VM AdoptOpenJDK (build 12.0.2+10, mixed mode, sharing)
    • Openjdk build "13" 2019-09-17 OpenJDK 64-Bit Server VM (build 13+33, mixed mode, sharing)
  • Linux (Xubuntu 18.04) using
    • Oracle build "1.8.0_221" Java HotSpot(TM) 64-Bit Server VM (build 25.221-b11, mixed mode)
    • Oracle build "11.0.4" 2019-07-16 LTS Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.4+10-LTS, mixed mode)
    • Oracle build "12.0.2" 2019-07-16 Java HotSpot(TM) 64-Bit Server VM (build 12.0.2+10, mixed mode, sharing)
    • Openjdk build "13" 2019-09-17 OpenJDK 64-Bit Server VM (build 13+33, mixed mode, sharing)
  • MacOS Mojave 10.14.6 using
    • Oracle build "11.0.4" 2019-07-16 LTS Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.4+10-LTS, mixed mode)
    • Oracle build "12.0.2" 2019-07-16 Java HotSpot(TM) 64-Bit Server VM (build 12.0.2+10, mixed mode, sharing)
    • Openjdk build "13" 2019-09-17 OpenJDK 64-Bit Server VM (build 13+33, mixed mode, sharing)
Note that Zelix KlassMaster™ version 13 will currently not run successfully on the Eclipse OpenJ9 JVM. This issue is under investigation but it appears to be due to a JVM bug.

What can Zelix KlassMaster™ process?

Zelix KlassMaster™ can process bytecode compiled for Java 9, 10, 11, 12 and 13 including modules.

Of course, it can also process bytecode compiled for JDK 1.1.x, 1.2.x, 1.3.x, 1.4.x, 1.5.0, 1.6.0, 1.7.0 and 1.8.0 JVMs. However, it is highly recommended that you always set the internal classpath used by Zelix KlassMaster™ (i.e. the ZKM Script classpath statement) to point to the bootstrap classes corresponding to the classes you are obfuscating. For Java 2 through to Java 8 that is the corresponding rt.jar. For Java 9 to Java 13 it is the corresponding lib\jrt-fs.jar file system.

Note that if you use the Reference Obfuscation functionality on bytecode which is at the Java 8 level then your obfuscated bytecode will require a newer Java 8 or better JVM to run. For example, if you use an Oracle JVM earlier than 1.8.0_152 then you may get a JVM crash due to HotSpot bugs.
 
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