FAQ 3.20 How can I hide the source for my Perl program?

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This is an excerpt from the latest version perlfaq3.pod, which
comes with the standard Perl distribution. These postings aim to
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to review and update the answers. The latest version of the complete
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3.20: How can I hide the source for my Perl program?

    Delete it. :-) Seriously, there are a number of (mostly unsatisfactory)
    solutions with varying levels of "security".

    First of all, however, you *can't* take away read permission, because
    the source code has to be readable in order to be compiled and
    interpreted. (That doesn't mean that a CGI script's source is readable
    by people on the web, though--only by people with access to the
    filesystem.) So you have to leave the permissions at the socially
    friendly 0755 level.

    Some people regard this as a security problem. If your program does
    insecure things and relies on people not knowing how to exploit those
    insecurities, it is not secure. It is often possible for someone to
    determine the insecure things and exploit them without viewing the
    source. Security through obscurity, the name for hiding your bugs
    instead of fixing them, is little security indeed.

    You can try using encryption via source filters (Starting from Perl 5.8
    the Filter::Simple and Filter::Util::Call modules are included in the
    standard distribution), but any decent programmer will be able to
    decrypt it. You can try using the byte code compiler and interpreter
    described later in perlfaq3, but the curious might still be able to
    de-compile it. You can try using the native-code compiler described
    later, but crackers might be able to disassemble it. These pose varying
    degrees of difficulty to people wanting to get at your code, but none
    can definitively conceal it (true of every language, not just Perl).

    It is very easy to recover the source of Perl programs. You simply feed
    the program to the perl interpreter and use the modules in the B::
    hierarchy. The B::Deparse module should be able to defeat most attempts
    to hide source. Again, this is not unique to Perl.

    If you're concerned about people profiting from your code, then the
    bottom line is that nothing but a restrictive license will give you
    legal security. License your software and pepper it with threatening
    statements like "This is unpublished proprietary software of XYZ Corp.
    Your access to it does not give you permission to use it blah blah
    blah." We are not lawyers, of course, so you should see a lawyer if you
    want to be sure your license's wording will stand up in court.


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