'Protecting' Perl Code?

An anonymous reader asks: "Ok, so here is the scenario: my company has some software that is used internally and it is written in Perl. We now need to put this code on a server that has 'public' access (it's a university machine). We provide root access to the system for the purpose of learning, but we need to keep the code from being viewed or edited. Is there anything to do besides the 'perl2exe' and the ActiveState compiler? How effective are those really at protecting code?"

Comments

Heard of B::Deparse? Time to learn.

[dondelelcaro]

This is such a frequently asked question that there's even a faq in the documentation that is distributed in almost every single perl distribution.

perldoc -q 'hide the source'

If that's not simple enough, then see the thread on perlmonks.org about it.

If you still think that obfuscating the source code is going to gain your company anything, then I doubt anyone really wants to see your code at all. (You don't happen to work for Blackboard, do you?)

Re-examine your need

[orkysoft]

If you are giving root access to the machine to students, you do not need to put your preciousss perl application on the same machine. In fact, you need to NOT put it there, because even if you obfuscate it, encrypt it, or compile it, it's possible to reverse the process. Obfuscated code can be analyzed and understood, plus it's going to take some real talent and time if you want to do it right, so it's expensive. Encrypted code needs to be decrypted before it can be executed. Compiled code can be decompiled.

You might use something like a BSD Jail or some other kind of server virtualization, so it merely looks like your software is on another machine. If it is really important that this program remains your dirty little secret, don't put it on a machine which you don't control. Really.

But if you really want to put it on the same machine, try compiling it into a binary, and not draw any attention to it, to avoid people getting curious about it. Still, if someone finds it and takes enough of an interest in it, all bets are off.

GrSecurity

[BusDriver]

Why don't you install yourself a nice Kernel with grsecurity.

Using it's permissions system, you can allow root to login and do whatever you'd like, you but can set grsec so that only certain other groups/systems are able to view/run etc your perl code.

The permissions system is very configurable and it's a steep learning curve with not a real lot of documentation. But playing with it for a few days should get you all figured out.

Using grsec it's possible to allow root to login and really do zero damage, it's a great system. I don't think any Linux box should be allowed on the 'net without this patch! There are other systems (SeLinux) that offer the same sort of thing, so if GrSec isn't quite what you need be sure to look at the others.

Using a system like this means all those "they have root forget about it" isn't true anymore, you can configure it so root can do very little damage to the working system, but still have access to edit all those files the normal pleb user accounts can't.

Tim

Re:Not Possible, Permissions, Jails/Sandboxes, Oth

[chromatic]

Perl is already Tolkienized -- just look at the start of every source file!

More seriously, you can save the internal representation, but it's easy for someone skilled to turn that back in to mostly-readable source code. You don't even lose the variable names; Perl keeps them around. (For globals, you have to -- you always have to do a symbol lookup. Lexicals don't have symbolic access; the compiler turns these into indexes into pads attached to the internal representations of code objects. However, these lexical pads do keep the variable names around as they're important for error messages, among other things.)

(Guess who just wrote about lexical pads in a Perl book not more than ten minutes ago?)