How do I protect my PHP source code when selling a website to clients?

Question

I would like some advice Lets say I've made a product eg. Car rental Website/System (PHP & MySQL) I want to sell it to 40+ Car rental companies How do I stop eg. 'SA-Rentals' from just copying the code and giving/selling it to 'Cars 4U-Rentals'

Safest way I can think of is using Multitenancy where each client will have a subdomain (eg. cleintname.myproduct.com) I've also looked at PHP Obfuscation and Encoding but it looks to easy to Decode/Modify

Ideally We want to sell them the product and then let it's out of our hands. (low maintenance)

if you're using php, and it runs on their servers, it's not really worth it and there's not too much you can do once they have the code, however using it without your permission etc. runs into copyright issues and you could sue them. That's why many companies open-source their software but sell installation/maintenance/help support services. Your best protection is hosting yourself, or hosting portions of the code yourself and requiring their servers to make requests to your servers in order to execute, or adding a compiled plugin to PHP itself that is closed source. — serakfalcon, Aug 20 '14 at 13:43

score 7 · Answer 1 · answered Aug 20 '14 at 13:42

7

The best way to "legally" protect you is stating that point clearly in the license the customer will obtain when you sell it (mind that you're actually just selling a license not the software itself!).

To protect your code from non-legal actions (like selling the code no matter the license) your only option is to actually host those websites yourself. Obfuscators provide some protection (aka makes the process of decoding your code slower) but still your software won't be protected from reselling but just from unwanted edits!

answered Aug 20 '14 at 13:42

Luca B.

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4
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The best solution to prevent re-selling I've seen was to place a text file somewhere strange containing the version number, if the code was ever copied to another server it wouldn't find the version number and would be able to error out asking for you to contact support. Again, not a perfect solution, once someone either de-obfuscates the code or just watches for filesystem access it becomes obvious how to resolve the problem. – scragar Aug 20 '14 at 13:49

score 2 · Answer 2 · answered Aug 20 '14 at 13:45

As you mentioned, obfuscation isn't fool proof. So, your only options are in licensing. Make sure you distribute the software with the right licensing, the customers sign the agreement with you when you sell them the site. They're bound by the license and if you discover they're in violation of it, you have a case. In my experience, few companies are going to want to take that code and start extending it or altering it and if they've bought the software for the purpose of their business, getting into the software development business is a whole new direction.

As Luca mentioned, your only sure way is to host the service yourself and then the customers never get the code. Unfortunately, you incur infrastructure costs, so your licensing model needs to change accordingly.

One other option would be to offer two different licenses, charging those that want to change it more upfront with the understanding they don't distribute it in the license agreement.

score -2 · Answer 3 · edited May 12 '18 at 12:40

I have the same problem, and thanks to @Brian Fegter, you can use the following working code that searches for your copyright citation.

add_action('template_redirect', 'foobar_explode_if_no_citation');

function foobar_explode_if_no_citation(){

    #Get the absolute server path to footer.php
    $footer_path = locate_template('footer.php');

    #Store the footer file contents in a var
    $footer_contents = file_get_contents($footer_path);

    #The required string
    $citation_string = 'Designed by Foo Bar';

    #Set off the nuclear bomb if there is an egregious offense
    if(!preg_match("/$citation_string/", $footer_contents))
        exit('All your website belongs to me. Make sure this string "Designed by Foo Bar" is included in footer.php');
}

All you need to do is change $citation_string to match yours, for example: Designed by Foo Bar

The code will search into the file footer.php (you can change it with any file name) for the string "Designed by Foo Bar", if it doesn't find it it will output a warning message, for example

All your website belongs to me. Make sure this string "Designed by Foo Bar" is included in footer.php

Also if you want to add a link in your citation you just need to replace the preg_match() by this (credit goes to @Rizier123 )

if(!preg_match("/" . preg_quote($citation_string, "/") . "/", $footer_contents))

I think it will help others who work days and nights coding. Peoples must respect copyrights.

How do I protect my PHP source code when selling a website to clients?

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