perldoc Filter::decrypt says:

Assuming you haven't taken any steps to spot when the compiler is in use and you have an encrypted Perl script called "myscript.pl", you can get access the source code inside it using the perl Compiler backend, like this perl -MO=Deparse myscript.pl Note that even if you have included the BOOT: test, it is still possible to use the Deparse module to get the source code for individual subroutines.

among other things. Hope that helps.

After Compline,
Zaxo