protecting java code from decompilation

[ashishingle]

I am developing a commercial mobile application. I am new to to j2me. While goggling many times i follow nokia forum for help. & Frankly It helped me a lot.

My query is Can we protect access to jar file by the following way
1>User need to download the application i.e jar file from server only?
2> Server will allow only mobile phones to download the app using User agent Header i.e . PC ,PDA etc will not be allowed to download?.
Is it possible..??


-Ashish

[skalogir]

Hi Ashish and Welcome to Nokia's Discussion Boards,

You would need to perform OTA deployment in connection with implementing a server side protection scheme such as rejecting a request from a specific client type, though it might not be safe enough. You can get more ideas on how the server side implementation can be in order for you to protect the jar file by checking this thread.

Why not publish the application to Nokia Store? Given that your application is commercial, it might be the best channel. The distribution via Nokia Store is done in such a way so that the .jad and .jar files are protected and hidden from the end user. Installation takes place directly on the device, via Nokia Suite (provided that the end user has connected the phone to the PC) or the native Nokia Store application that can be found on the phone.

[petrib]

The distribution via Nokia Store is done in such a way so that the .jad and .jar files are protected and hidden from the end user.

While a typical end-user when downloding an app from the Nokia Store, is unable to intercept and get the actual installation file, it does not mean that a sufficiently skilled person cannot get it. In other words, do not assume that the Nokia Store distribution is fully secure. Nokia Store makes no software piracy prevention claims or guarantees.

And once access to the .jar, the .class files are also accessible and can be decompiled. Using an obfuscator makes them harder to make sense of.

[balagopalks]

While a typical end-user when downloding an app from the Nokia Store, is unable to intercept and get the actual installation file, it does not mean that a sufficiently skilled person cannot get it. In other words, do not assume that the Nokia Store distribution is fully secure. Nokia Store makes no software piracy prevention claims or guarantees.

Agree with Petrib here, even I have heard from few developers that they have managed to get app files during installation with Store Client.

Regards
Gopal

[jeffrey.halimsetiawan]

Perhaps, I suggest you to use Obfuscator as your minimal protection. So, in case someone decompile your code, they can't understand your code easily.

[r2j7]

Hello Ashish,

and welcome to Nokia Developer Discussion Boards!

About obfuscators: http://www.developer.nokia.com/Commu...ki/Obfuscation

Regards,
r2j7