java restrict decompile of some classes

Question

Is it possible whenever a class is decompiled display some junk code.?But while running the same class it should work properly? I know this may look weird, is it really possible? or restrict decompile of some classes from the JAR

score 2 · Answer 1 · answered Jun 13 '13 at 06:49

2

No it is not possible, however you can obfuscate the code so that it would be less readable. Usually it is sufficient solution.

answered Jun 13 '13 at 06:49

Michal Borek

4,584
2
30
40

score 2 · Answer 2 · answered Jun 13 '13 at 06:49

2

The classes you are trying to decompile may be obfuscated.

From wiki:

Obfuscation is the deliberate act of creating obfuscated code, i.e. source or machine code that is difficult for humans to understand.

Programmers may deliberately obfuscate code to conceal its purpose (security through obscurity) or its logic, in order to prevent tampering, deter reverse engineering, or as a puzzle or recreational challenge for someone reading the source code.

For more details read this : http://en.wikipedia.org/wiki/Obfuscation_(software)

There are tools available to obfuscate your code, here are couple of them:

http://www.yworks.com/en/products_yguard_about.htm

http://proguard.sourceforge.net/

answered Jun 13 '13 at 06:49

Juned Ahsan

67,789
12
98
136

1

If you quote something it is very nice if you can also add a link to the source. Otherwise one might think that it is your own words. In this case you are quoting from wikipedia so add a link to it please. – maba Jun 13 '13 at 06:52
@maba i quoted it to give the impression that it is picked from somewhere. Anyways i accept your suggestion and i have edited the post accordingly. Thanks! – Juned Ahsan Jun 13 '13 at 06:54

score 1 · Answer 3 · answered Jun 13 '13 at 06:49

1

It's possible to a degree. Not actual garbage characters, but code that's fairly hard to decypher. What you're looking for is called a "Java bytecode obfuscator." There are a bunch of them, both commercial and non-commercial. At the end of the day, though, if the JVM can read and correctly run your code, it can be decompiled.

Note that bytecode obfuscation can get in the way of the JVM's various optimizations.

answered Jun 13 '13 at 06:49

T.J. Crowder

1,031,962
187
1,923
1,875

Ohh he's wants to know about code obfuscation...Didn't get it. – alvinarul Jun 13 '13 at 06:51
@AlvinArulselvan: Bytecode, though, not source. – T.J. Crowder Jun 13 '13 at 06:52
https://www.owasp.org/index.php/Bytecode_obfuscation is a good resource to read for that – alvinarul Jun 13 '13 at 06:58
Thx for the details. I would like to obfuscate a single package only and its all dependent classes and non-java resources files. Can anybody let me know if this is possible using proguard. if yes how we can achieve this? – hanmayya Jun 17 '13 at 05:12

java restrict decompile of some classes

3 Answers3