How to encrypt HTML+JS assets in Android Phonegap mobile app?

Question

I have mobile app created using Phonegap basic wrapper and HTML5. My goal is to encrypt files in assets directory (JS and HTML files) so they are unreadable to people, who u

Answer 1

The best combination I've found is the DojoToolkit and the Closure Compiler in Advanced Mode.

Closure in Advanced Mode makes JavaScript code almost impossible to reverse-engineer, even after passing through a beautifier. Once your JavaScript code is obfuscated beyond any recognition and any possibility to reverse-engineer, your HTML won't disclose much of your secrets.

This link for using the Dojo Toolkit with the Closure Compiler in Advanced Mode for mobile applications:

http://dojo-toolkit.33424.n3.nabble.com/file/n2636749/Using_the_Dojo_Toolkit_with_the_Closure_Compiler.pdf?by-user=t

And of course the Dojo Toolkit works well with PhoneGap.

Answer 2

There is no easy way to do this. If you want to encrypt your JavaScript you would need some sort of key to decrypt it with. The key cannot be stored on the device since then it's easy to find the key and decrypt the source code. Iff your application requires a user to login you could possibly return the encryption key once the user is logged in and use that key to decrypt JS and HTML files. There are standard Android encryption libraries that you can use via a PhoneGap plugin.

Having said that, it's just JavaScript so if there is something that you really need to have encrypted you should probably consider changing your approach.

Answer 3

Some time ago I have same problem but on iOS. And the result was only after patching PhoneGap for iOS. I have wrote an article at http://oleksiy.pro/2011/09/20/phonegap-application-encryption/. Also, for Android this method could be weak, because java code could be 99% decompiled, and hacker will see your key.

Answer 4

You can use a webview and load a base64 string:

protected String base64Str = "+wL00h2L....";
wv1.loadData(base64Str, "text/html; charset=utf-8", "base64");