Protect Your Flex and ActionScript Code with Effective Obfuscation Strategies

As developers, we strive to create amazing applications using frameworks like Flex and ActionScript. However, a common concern arises when it comes to protecting our hard work and code from unauthorized access and decompilation. This blog post addresses the apprehensions of a developer who discovered that their ActionScript packages were visible when viewed through a decompiler—a situation that can be particularly alarming. But fear not! We will explore effective obfuscation techniques to enhance code protection.

Understanding the Problem

When you compile your Flex application into a SWF file, the underlying ActionScript code can be extracted using various decompilers available online. This scenario poses a risk, especially if your application contains sensitive logic or proprietary functions that you do not wish to expose.

The developer in question highlighted their concern about the ease with which anyone could decompile their code and access the logic behind their application. While they mentioned that the MXML files might not be straightforwardly decompiled, they were still eager to find a way to obfuscate their code further.

The Solution: Steps to Obfuscate Flex & ActionScript Code

Here’s a structured approach to help safeguard your application using effective obfuscation methods:

Step 1: Compile Your Application to SWF

Before applying any obfuscation, you need to compile your Flex application into a SWF file. This file is necessary for the subsequent steps.

Step 2: Encrypt the SWF File

• Use AES Encryption: Secure your SWF file by encrypting it with Advanced Encryption Standard (AES). This step ensures that even if someone accesses your SWF file, they cannot easily read its contents.
• Tools Required: You can use various libraries or tools for AES encryption that are compatible with ActionScript.

Step 3: Create a Wrapper Application

Next, you need to create a “wrapper” application that serves as a secure shell for your encrypted SWF.

• Load the SWF into a ByteArray: Utilize URLLoader to load the encrypted SWF file into a ByteArray. This method prevents direct access to the SWF file from unauthorized parties.

Step 4: Decrypt During Runtime

• Use as3crypto Library: Implement the as3crypto library to handle decryption.
• Decrypt at Runtime: After loading the encrypted SWF, decrypt it within your wrapper application during runtime using the AES key.

Step 5: Load the Decrypted SWF

• Utilize Loader.loadBytes: Finally, once decrypted, employ Loader.loadBytes to load the decrypted SWF into your application. This way, your operational code remains hidden during its transportation.

Considerations for AIR Applications

If you are developing an AIR application:

• Leave SWF Encrypted: You can choose to deliver your application to the end-user with the SWF still encrypted.
• Provide a Registration Key: Create a registration process where users obtain a key that allows them to decrypt the SWF, adding another layer of security.

Additional Resources

To assist further with your obfuscation journey, you can explore obfuscators designed for ActionScript. Here is a link to a potential option:

• AS3 Obfuscator

Keep in mind that while these methods will significantly increase the difficulty of accessing your code, no solution is truly foolproof. Obfuscation should be part of a multi-layered security strategy.

Conclusion

Protecting your Flex and ActionScript code from decompilation is crucial for safeguarding your intellectual property and maintaining the competitive edge of your applications. By following the steps outlined—compiling to SWF, encrypting, creating a wrapper application, and more—you can create a robust shield against unauthorized access. Remember, the goal is to make it harder, not impossible, for others to retrieve your hidden code.

Embrace these strategies, and empower your development work with effective obfuscation techniques today!