Free SWF Encryptor, Obfuscator and Protectors!

1. Makc3d's open source SWF obfuscator written in AS3 (WTFPLv2):
http://makc3d.wordpress.com/2010/02/09/open-source-swf-obfuscator/
http://wonderfl.net/c/6WDD/
http://makc3d.wordpress.com/2013/01/27/free-swf-obfuscator-update/

2. SOB: Open Source SWF Obfuscator.
Can replace the strings in the SWF/ABC string table with random strings.
Source Code (C): https://github.com/badsector/sob

3. Action Script 3 Obfuscator: Python script that takes in a single .as file and makes it hard to decipher.
https://github.com/shapedbyregret/actionscript-3-obfuscator
http://jwopitz.wordpress.com/2012/02/01/as3-code-obfuscator

4. SWF File Obfuscator:
Source Code: http://sourceforge.net/projects/flmobf/

5. SWFLOCK: Online service to do domain lock, trial period and password protection, now free.
http://www.swflock.com/

6. Flash Protection Gold: Packing, domain locking and can add preloaders for your swf, now free.
http://www.avimpeg.net/flash_protection.htm

7. Flash Free Protection: A free tool that protect your flash files.
http://flashfreeprotection.blogspot.com/

8. OBFU: A Flash Action Script obfuscator:
http://www.opaque.net/~dave/obfu/
This software is really outdated, but its source code (C, GPL) may be useful. The junk opcodes insertion method is the classical way for cheating decompilers.

9. Actionscript Obfuscator: Flasm based, for AS1,2 only.
http://www.monokai.nl/blog/2006/08/02/actionscript-obfuscator/

10. Actionscript Source Obfuscator:
Obfuscates multiple Actionscript 3.0 source files by remaning all that can be renamed.
https://github.com/Sandremss/Actionscript-Source-Obfuscator

11. Flasturbate:
A open source SWF obfuscator based on RABCDAsm.
https://github.com/Teesquared/flasturbate

Links:

1. Способы «защиты» flash-приложений
(Ways to «protect» flash-applications, in Russian.
Try Google Translate!)
http://habrahabr.ru/blogs/Flash_Platform/110686/

2. Pack a SWF: http://active.tutsplus.com/tutorials/workflow/protect-your-flash-files-from-decompilers-by-using-encryption/

3. Junk instructions insertion method explained: http://www.gotoandplay.it/_articles/2004/04/swfProtection.php

4. [Tutorial] Applying ROT128 Encryption On Embedded/Module SWFs:
http://www.ghostwire.com/blog/archives/as3-applying-rot128-encryption-on-embeddedmodule-swfs/

5. [Tutorial] Domain Locking SWFs and Preventing SWFs From Running Locally:
http://www.ghostwire.com/blog/archives/as3-domain-locking-swfs/
http://www.ghostwire.com/blog/archives/as3-preventing-swfs-from-running-locally/
FusionLock – Simple SiteLock AS3 package:
http://profusiongames.com/blog/fusionlock/

6. Anti-Cheat Methods
Keep the CheateEngine out of your Flash Online Games:
http://danielbunte.de/2012/02/16/keep-the-cheateengine-out-of-your-flash-online-games/
Secure Your SWF Files Against the Cheat Engine:
http://voices.yahoo.com/secure-swf-files-against-cheat-engine-using-2513602.html?cat=15

https://www.mochimedia.com/community/forum/topic/anti-cheat-methods-for-mochiads-games
http://www.kongregate.com/forums/4/topics/25698

7. An Introduction to SWF Obfuscation:
http://bmanatee.blogspot.com/2013/07/an-introduction-to-swf-obfuscation.html

8. Advanced protection of Adobe AIR content:
http://gamespoweredby.com/blog/2014/09/advanced-protection-of-adobe-air-content-desktop-only/

9. More:
https://www.fgl.com/blog/2010/11/how-to-protect-your-game-from-being-rebranded/
http://www.playgb.com/page/how-to-avoid-external-link-blocking?c=17