How to license C++ software : <p>I would like to start selling some software I have developed in C++. The first line of protection will be the fact that C++ produces an executable. Within that, I will also apply algorithmic and manual obfuscation techniques to make it very hard to understand even once cracked.</p>

<p>With regards to licensing, my plan is to create an API you can send a request to. The data will include your license key and your device fingerprint. Upon receiving this data, the API will check for the license key in the database, and ensure the device fingerprint matches the fingerprint stored. If it does, it will reply with some sort of cryptographic response that must match a certain pattern. The client will then check if that response matches the pre-determined pattern, and if it does the software will be allowed to be used. If it does not, the user will be locked out. And this response will be empty if the API check failed, so that will also cause the user to be locked out.</p>

<p>I am aware that this is not unbreakable, but I would like to make it as difficult to break as possible without investing a ridiculous amount of time. The reason I wanted to add some cryptographic response is so the user can't just spoof the response from my server. Although I will also be using HTTPS on top of that. If this is a good idea, what sort of cryptographic check would you recommend?</p>

<p>The idea of the fingerprint is to prevent users from using the software on multiple computers at a time. I'm not quite sure what to use for this, but I was thinking of hashing a combination of the MAC address, computer name and something else. Any suggestions?</p>

<p>Is there anything else I should be doing to protect my software?</p>

<p>Thanks.</p>
