How to protecting java lincence checks agains decompiling ?
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Posted By:   Sebastien_Spas
Posted On:   Friday, June 1, 2001 10:23 AM

Hi, I'm working on a Java application which is doing some licence checks using a third part licence software (flexlm). This provide secured licence files and a java API to check licence. So, I added something like that in my code : LicenceChecker.check("/opt/licence.dat"); and it throws a security exception if the licence is wrong. This mechanism is working well. But, nothing prevent a hacker to decompile the class which implementents this check, and use the application without the licence. Is there some mechanisms available to protect agains that ? I played a bit with jar signing, and integrity of class files is assured, but once again nothing prevent a hacker to decom   More>>

Hi,

I'm working on a Java application which is doing some licence checks using a third part licence software (flexlm).

This provide secured licence files and a java API to check licence.
So, I added something like that in my code :
LicenceChecker.check("/opt/licence.dat");
and it throws a security exception if the licence is wrong.
This mechanism is working well.

But, nothing prevent a hacker to decompile the class which implementents this check, and use the application without the licence.
Is there some mechanisms available to protect agains that ?
I played a bit with jar signing, and integrity of class files is assured, but once again nothing prevent a hacker to decompile my jar file, replace the licence check class and recompile it and sign it with his own certificate.

   <<Less

Re: How to protecting java lincence checks agains decompiling ?

Posted By:   Stephen_Kinser  
Posted On:   Thursday, December 6, 2001 05:13 PM

There is a solution at www.jarsafe.com that protects Java programs without using obfuscation. It protects them by using encryption. A free download is even available.

Re: How to protecting java lincence checks agains decompiling ?

Posted By:   John_Mitchell  
Posted On:   Saturday, June 16, 2001 07:17 PM

Correct. A serious enough cracker can get around it. You might make it a bit harder for the cracker by using one of the "obfuscator" programs.

Personally, I suggest that you stop using license managers completely. They are a major PITA, IMHO.

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