Obfuscating JavaScript code

Question

Some Flash developers are afraid of JavaScript. Their point of view:

Stealing JS source code is effortless, one would just 'view source' and copy it. Yes, you can decompile Flash bytecode, however it requires more time and knowledge. As a result, JavaScript is not suitable for commercial software development, because competitors will steal the code and put the original developer out of business.

Does obfuscating JavaScript code make sense when developing commercial web applications?

Are there any obfuscation techniques that actually work? Are large companies like Google obfuscating their web application code. For example are Gmail or Google Drive somehow protected?

Answer 1

I think the operative word in the question here is "afraid." The aversion is based on fear, not fact. The reality is, the threat model isn't particularly realistic. Commercial web software development companies nearly universally use JavaScript these days, obfuscated or otherwise, and I challenge you to find me even a single example of one that's had it's JS stolen by a competitor and then been driven out of business because of it. I'm quite confident that it hasn't happened, and isn't likely too.

Too your second question, do companies like Google obfuscate their JavaScript? Yes, but not for security! They obfuscate to minimize the size of the code, in order to reduce the download size and minimize the page load times. (See the Google Closure Compiler.) This is not necessarily how you'd obfuscate for security because the only goal is to minimize the number of bytes that have to be delivered to the client. This is what you should be focused on with JavaScript, not worrying about whether someone will be able to read it or not.

Answer 2

No. Obfuscating Javascript usually makes no sense whatsoever. Always assume that any logic you place on the client side can easily be obtained by a determined enough attack no matter how you obfuscate it.

Your "important" logic should be stored server side.

Answer 3

You seem to already know that obfuscation isn't actual protection, so I'm not gonna lecture you on security by obscurity.

What makes sense is this: Put your competitive code on the server to protect it, then obfuscate client-side code as much as you want. Granted, it won't give you much security but it'll definitely deter kiddies snooping around, and it'll create an impression of stronger security as a part of security theatre. Google is doing it with GMail, Facebook is doing it.

Keeping in mind that your code will be deobfuscated, you can still obfuscate it as a part of your build process to make your clients and users happier.

There are many tools you can use to achieve that: Free Javascript Obfuscator, and JScrambler (commercial) are two tools I've used before.

Update: After a discussion on The DMZ, we've concluded that yes, Google and Facebook are doing it, but probably only for file size and performance and there's doesn't seem to be anything that suggests it's part of security theatre.

Answer 4

Of course this is a baseless fear.

Javascript is only one part of a larger ecosystem, much more important is brand, site usability, site integrity, responsiveness and network effects.

Yeah, javascript minimisation, optimisation is good to do, but not because of these purposes.

If a competitor steals you code, you can go legal on their tails, and kill their reputation, but are they going to be so stupid (it is in the clear on their site too)?

And this argument can be made for html and images too, you obviously need to take down your whole website because people can steal it.

Personally I only obfuscate to hide my xxxxpy code ;) and take out the comments lol.

Answer 5

It the code works, obfuscation is worthless. Take this example:
Before obfuscation:

function say(whatever){ alert(whatever); } 

after:

eval(function(p,a,c,k,e,d){e=function(c){return c};if(!''.replace(/^/,String)){while(c--){d[c]=k[c] ||c}k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1};while(c--){if(k[c]){p=p.replace(ne w RegExp('\\b'+e(c)+'\\b','g'),k[c])}}return p}('1 3(0){2(0)}',4,4,'whatever|function|alert|say'.sp lit('|'),0,{})) 

Now, not many people would really try to understand all of that mess, but if they want to steal it, they don't need to.

The obfuscated version can be called just like the original version: say("hi").

If you don't know how the original version is called, locate the function/event where you get an alert and check if it uses a custom function instead of alert, Then use CTRL + F to find this function.

As a last resort one would simply parse the RegEx, in my example most of the "obfuscation" is just RegEx conversions of function names to the real ones at runtime. Noticed 'whatever|function|alert|say'?