ActionScript code protection - AbsoluteAstronomy.com

ActionScript code protection. ActionScript

ActionScript

ActionScript is an object-oriented language originally developed by Macromedia Inc. . It is a dialect of ECMAScript , and is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on Web pages in the form of...

is the main language for developing flash products.
Code obfuscation

Obfuscated code

Obfuscated code is source or machine code that has been made difficult to understand for humans. Programmers may deliberately obfuscate code to conceal its purpose or its logic to prevent tampering, deter reverse engineering, or as a puzzle or recreational challenge for someone reading the source...

is the process of transforming code into a form that is unintelligible to human
readers while preserving the functionality and structure for computers. Flash developers use a variety of code encryption and obfuscation methods in order to but most obfuscation methods are kept secret because they are used in popular ActionScript obfuscators.

Overview

Obfuscation is the process of modifying ActionScript code. Obfuscation engineering makes it impossible to use the original code for programming by mixing up functions, arguments and variables names; however the SWF file with obfuscated code stays readable for Flash players.

ActionScript obfuscation algorithms are aimed to resist Flash decompilation and protect development's work from stealing. Nowadays, there are many different freeware and shareware tools that provides different obfuscation options. Some SWF Protectors implement lexical transformations - such as identifiers renaming, control flow transformation, and data abstraction transformation - that make it harder for decompilers to generate correct and usable output. Others - insert certain traps based on decompilers imperfections. Some decompilers manage to open protected files and maybe extract some of its resources (sounds, images, etc.), but they cannot read the ActionScript code correctly. It often happens that when protected SWF file is added to decompilation software, the latter may crash or quit unexpectedly.

Examples

The easiest way to understand the benefit of SWF obfuscation is to compare a non-protected SWF ActionScript code with protected one.

ActionScript 2.0

Code before obfuscation:

stop;
if (this.holder1 Number (this.holder1)) {
loadMovieNum ("jopeClipLoader5.swf", this.holder1);
} else {
this.holder1.loadMovie("jopeClipLoader5.swf");
}

Code after obfuscation:

do {
if (false) {
( add .holder1);// not popped
if (true) {
// unexpected jump
do {
stop;
} while (false);
// unexpected jump
if (false) {
Set("\x0B\x1A\x13\x16", true);
} while (true);
do {
if (true) {
// unexpected jump
// unexpected jump
if (false) {
} while (true);
do {
// unexpected jump
} while (true);
// swfAction0xAD hexdata 0x52,0x17,0x99,0x02,0x00,0x39,0x00,0x9A,0x01... // Unknown action
}
( add .holder1)[(!"holder1".holder1).holder1].loadMovie;
// unexpected jump
/* Error1016 */
// unexpected jump
do {
(this);// not popped
if (true) {
// unexpected jump
} while (this);
(this);// not popped
// unexpected jump
}
}
}
if (false) {
} while (true);
do {
// unexpected jump
} while (true);
// swfAction0xAD hexdata 0x52,0x17,0x99,0x02,0x00,0x39,0x00,0x9A,0x01,0x00,0x00,0x99... // Unknown action
}
"holder1".holder1.loadMovie;
// unexpected jump
/* Error1016 */
// unexpected jump
do {
(this);// not popped
if (true) {
// unexpected jump
} while (this);
(this);// not popped
// unexpected jump
}
}
}
Set("\x0B\x1A\x13\x16", true);
} while (true);
do {
( /* Error1010 */);// not popped
if (true) {
// unexpected jump
// unexpected jump
if (false) {
} while (true);
do {
// unexpected jump
} while (true);
// swfAction0xAD hexdata 0x52,0x17,0x99,0x02,0x00,0x39,0x00,0x9A,0x01,0x00,0x00,0x99,0x02... // Unknown action
}

ActionScript 3.0

Code before obfuscation:

private function getNeighbours(i:int, j:int):Array{
var a:Array = new Array;
for (var k = 0; k < 8; k++){
var ni = i + int(neighbour_map[k][0]);
var nj = j + int(neighbour_map[k][1]) ;
if (ni < 0 || ni >= xsize || nj < 0 || nj >= ysize)
continue;
a.push(Cell(cells[ni][nj]));
}
return a;
}

Code after obfuscation:

private function getNeighbours(_arg1:int, _arg2:int):Array{
var _local3:Array = -(((null - !NULL!) % ~(undefined)));
var _local4:*;
var _local5:*;
var _local6:*;
_local3 = new Array;
_local4 = 0;
for {
_local5 = (_arg1 + int(!NULL!));
_local6 = (_arg2 + int(!NULL!));
if (true){
_arg1 = (((//unresolved nextvalue or nextname << !NULL!) + !NULL!)
<< undefined);
_arg1 = (!(!NULL!) ^ !NULL!);
(!NULL! instanceof !NULL!);
var _local1 = (((!NULL! as !NULL!) + !NULL!) this);
if (!(!NULL!

!NULL!)){
-((true << !NULL!)).push(Cell(cells[_local5][_local6]));
}
}
if (!true){
(_local6 < 0);
(_local6 < 0);
(_local5 < 0);
}
}
return (_local3);
}

Adobe documentation and references