Matlab Compiler: protecting re-distribution of software during installation

Question

I'm considering using Matlab Compiler to distribute software for a price. I'm investigating (very) simple methods to discourage re-distribution without annoying users. Any recommendations?

One thought is to email a user a license key and have them input this during the installation process to be verified on a license server. If the key matches what is on the server, the installation proceeds as usual, otherwise, a warning message is shown to inform the user to purchase another license. However, this method requires a specified function to run only during the installation process, and not thereafter (so as not to annoy the user). Is this possible using Matlab Compiler or otherwise?

I suppose I could create a file on the user's disk that the program looks for when it starts (if it exists, then it is not being run for the first time), but if the user copies the whole directory, that file would get copied too.

Answer 1

In order to create an effective licensing system, you have to link it to one or more properties of a user machine (MAC address, OS ID, hard disk serial numbers, CPU serial numbers, etc...).

If you don't to this, you are just going to release licenses that can be transferred from one user to another. If one user decides to spread his license file worldwide, you are doomed because everyone could potentially take that license file and use it to unlock your application.

But if you link your license files to one or more properties of a user machine, as mentioned above, you must be able to obtain these properties either:

1. before the user decides to buy your application;
2. when the user activates his license.

First Scenario

You release your software as a trial. When it is started for the first time, you set an expiration date in the registry or in a file well hidden somewhere. You check against the expiration date when the application starts and, once it is reached, you throw an error and you don't let the used play with your application anymore.

Within the application, you create a Register Now button somewhere. When it is clicked, the application retrieves the machine properties and passes them to the web page / form that will be opened to let the user perform the payment. That page will be in charge to validate the machine properties, receive the payment and, finally, deliver a valid license code based on these properties.

Within the application, you must implement the same logics that allowed your form to create the license code, because you will need to use them in order to validate the code itself every time your application starts. A pseudo-code example:

mp1 = GetMachineProperty1();
mp2 = GetMachineProperty2();
mp3 = GetMachineProperty3();
lc = GetLicenseCode();

if (~strcmp(sha1([mp1 mp2 mp3]),lc))
    errordlg('Invalid license code!');
    return;
end

This is the simplest path. But keep in mind that if one or more properties of the user machine change (because he changes a device or reinstalls his OS), his license will be invalidated and you will have to provide a customer assistance service that takes care of this kind of situations.

Second Scenario

This one is much harder. You will not be able to know the user's machine properties in advance. So your licensing system will work on a two-steps basis. You release a unique code (called LID for example) when the used purchases your application. Then, once the user inserts that it in your application, your application must send it back together with the machine properties. The final key (called LKey for example) is then computed and sent back to the user.

mp1 = GetMachineProperty1();
mp2 = GetMachineProperty2();
mp3 = GetMachineProperty3();
lkey = GetLicenseKey();

if (~strcmp(sha1([mp1 mp2 mp3]),lkey))
    errordlg('Invalid license code!');
    return;
end

Machine Properties

The first solution has been provided to you through a comment: the MachineGuid value located in the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography. It's pretty solid. But it will only work on Windows machines. Use winqueryreg to access the registry.

Another good alternative is the Window Domain Controller Security ID, which is another machine-specific unique identifier. You can retrieve it using Java code within Matlab:

wdc_sid = com.sun.security.auth.module.NTSystem.getDomainSID();

or through the Windows registry key HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Group Policy\GroupMembership. The registry approach should be the one to use if you want to maintain a certain backward compatibility with old Matlab releases. Unfortunately, the Window Domain Controller Security ID is another identifier that is available only on machines that run under Windows.

If you want to adapt your licensing system to every possible OS and environment, you have to use a more generic approach, based on universally accessible hardware properties: MAC adresses, hard disk serials and such things. As far as I know, the most reliable property is the MAC address, because its uniqueness, althrough not granted, is almost certain and it's very unfrequent to change a network adapter (there are more chances to break an hard disk actually). Retrieve the MAC adresses of the machine network adapters using Java code as follows:

mac_addrs = '';
net_int  = java.net.NetworkInterface.getNetworkInterfaces();

while (net_int.hasMoreElements)
    mac_addr = net_int.nextElement.getHardwareAddress();

    if (~isempty(mac_addr))
        mac_addrs = [mac_addrs, '-', sprintf('%.2X',typecast(mac_addr,'uint8'))];
    end
end

mac_addrs = mac_addrs(2:end);

The above computation produces a character array that represents the result of the concatenation of all the MAC addresses found on the machine. Again, for compatibility reasons, this may not work on old Matlab releases, so you have to use a much more complex approach, described here.

[EDIT]

This approach to retrieve the MAC address based on the underlying OS could be easier:

switch computer('arch')
    case {'maci','maci64'}
        [~,a]=system('ifconfig');
        c=strfind(a,'en0');if ~isempty(c),a=a(c:end);end
        c=strfind(a,'en1');if ~isempty(c),a=a(1:c-1);end
        % find the mac address
        b=strfind(a,'ether');
        mac_add=a(1,b(1)+6:b(1)+22);
    case {'win32','win64'}
        [~,a]=system('getmac');b=strfind(a,'=');
        mac_add=a(b(end)+1:b(end)+19);
    case {'glnx86','glnxa64'}
        [~,a]=system('ifconfig');b=strfind(a,'Ether');
        mac_add=a(1,b(1)+17:b(1)+33);
    otherwise,mac_add=[];
end

I found it in the comments of this article.