The encryption is done through custom C executable and the execution of encrypted binary code can only be done through another C executable (dummy Perl interpreter) and it does in-memory execution like this.

perl_run(my_perl);
eval_pv(buffer, TRUE);
[download]

Easily broken:

1. start a debugger
2. load the "encrypted" program from the debugger
3. set a breakpoint at the call to eval_pv(), or at the first instruction of eval_pv()
4. start the program
5. instruct the debugger to show the contents of buffer
6. copy contents of buffer to a text file
7. kill the program
8. exit the debugger

It was explained a thousand times or more, but once more for you:

Perl is designed to evaluate unencrypted source code, so at some point, you have to decrypt the encrypted code. Alternatively, you can feed perl a prepared parse tree, in unencrypted form. Again, you have to decrypt the encrypted tree before passing it to perl. B::Deparse can reconstruct perl source code from the tree, so you gain exactly nothing from using a tree.

Both ways, you have to decrypt the encrypted data, so your executable must contain the decryption algorithm and the required decryption key. Both can be exctracted from the executable to create an independant decryption tool. Or, as I explained above, one can simply stop the execution of the program at the point where the decrypted data is passed to perl API functions. That's usually much less work.

And there is NO WAY to prevent that.

See also:

• Re: Protection for Perl Scripts
• Re^2: Where should I have configuration information in a file or database
• Uncool Use Of Perl: perl2exe. decompile quick steps
• perl2exe - no more secrets
• Can you prevent MO=Deparse
• Decompile Perl2EXE back to original source
• PerlApp decompile?
• A real challenge

Alexander