Originally Posted by nation-x

Any of the encoders are vulnerable... this is why you should obfuscate your code before you encode it... 9 times out of 10 the decoded versions of the script don't work because decoding isn't perfect... most decoders can't decode the script exactly as you wrote it. If you obfuscate your code they have almost no chance of being able to fix errors after they decode it.

http://alexking.org/blog/2004/02/07/...ting-php-code/