encrypting perl code used with mod

moshkod has asked for the wisdom of the Perl Monks concerning the following question:

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Re: encrypting perl code used with mod_perl by ikegami (Patriarch) on Jul 17, 2006 at 07:57 UTC
It's impossible to prevent the customer from viewing the code. The customer has access to everything `perl` sees, trivially. Once he can see the code, he can trivially bypass integrity checks by removing the `die`, allowing him to edit the code freely. Perl can understand two kinds of code. Source code and byte code. It might be a bit trickier for the customer if the program was delivered as byte code (encrypted or not), but I suspect it's quite easy to recreate Perl source code from Perl byte code. It's not even necessary to do so. I'm telling you this so you realize that any protection you add will be rather easily circumventable. Consider that in your cost analysis. On the plus side, using encryption to protect your program — as ineffective as it might be — will grant you an extra legal weapon (and thus an extra bargaining chip) in the USA: The DMCA.	[reply] [d/l] [select]
Re^2: encrypting perl code used with mod_perl by diotalevi (Canon) on Jul 17, 2006 at 20:41 UTC
Perl doesn't know about bytecode either. It only reads source code. ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply]
Re^3: encrypting perl code used with mod_perl by ikegami (Patriarch) on Jul 17, 2006 at 20:59 UTC
Core module ByteLoader claims to be able to load bytecode.	[reply]
Re^4: encrypting perl code used with mod_perl by diotalevi (Canon) on Jul 17, 2006 at 21:07 UTC
Re^5: encrypting perl code used with mod_perl by ikegami (Patriarch) on Jul 17, 2006 at 23:37 UTC
Some notes below your chosen depth have not been shown here
Re: encrypting perl code used with mod_perl by shmem (Chancellor) on Jul 17, 2006 at 07:25 UTC
You might want to look into B::Bytecode. If your code comprises modules (.pm files), compile them into .pmc files, which are preferred over *.pm files by `use` and `require`. You can also use ByteLoader. Depending on the reasons you want to "encrypt" your source files, you could take several checksums of them and tell your customers that support is lost with any modifications. If you want to prevent them from "stealing" your code, don't deliver it. --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l] [select]
Re: encrypting perl code used with mod_perl by cwry (Monk) on Jul 17, 2006 at 07:16 UTC
Have you looked at Filter::Crypto? You might like to thoroughly read through the warning section, which points out why doing this is fairly pointless, and that it only prevents casual viewing.	[reply]
Re: encrypting perl code used with mod_perl by CountZero (Bishop) on Jul 17, 2006 at 10:29 UTC
If your customer is sophisticated enough to edit your scripts, he will not have a hard time decrypting your encrypted or otherwise obfuscated code. So you better go and see your lawyers and ask them to draft some strong legal text to stop the customer from messing with your code. One thing I have been thinking of (but only in theory as I lack the knowledge to implement it) is to write a compiled XS-module which would check on a regular basis that the scripts which are part of your project are still the same by comparing their MD5-hash with the original MD5-hash. It would not be too difficult to "hide" that XS-module somewhere in your project and have it called regularly from one of your other routines. If it finds any anomalies, it could throw an exception and stop executing the program. CountZero "If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law	[reply]
Re: encrypting perl code used with mod_perl by perrin (Chancellor) on Jul 17, 2006 at 13:32 UTC
Sorry, mod_perl doesn't support source filters. You can try using PAR for this, if you just want to make it a little harder.	[reply]
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