Flash Secure Optimizer

Flash Secure Optimizer (FSO) is a software that can protect ActionScripts and compress SWF files. Support Flash CS4 and ActionScript 3. Identifier Renaming(Identifier Obfuscation), Strings Encryption, Encrypted Domain Locking, Obscuring ActionScripts. FSO lets you reduce SWF file size by optimizing/compressing most parts of SWF file. FSO provides you a simple custom user interface you have only some clicks to protect/optimize your SWF files.
Working with Flash Secure Optimizer (FSO) is very simple. You have just 3 steps:

Adding one or more files to your project.
Selecting identifiers to rename from identifiers list and setting optimization options.
Clicking on the Build Output button.