The following items are hashed into the unlock key:

Most likely, it would be the product feature. Additionally, your software company can easily invalidate all the keys floating around in the marketplace by simply changing one of the items in the hash. 01%, how many of those are going to give away a hacked key to thousands of people? Also, since this method hashes all of the following items, any hacker would still need to know these things to create the keys for other people's copies. 99.99% of people don't have the time to spend hacking unlock keys. See other articles at Microsoft on how to obfuscate cipher keys in your deployed applications. The method presented here is as secure as you are able to keep your company cipher keys. This is a very common way of purchasing software that we are all familiar with. They can freely re-install the software on multiple machines, but the key will only unlock the copy they downloaded.

User is now in possession of an unlocked software and a key that cannot unlock any of my other products.

All of the above must be true for the emailed key to actually unlock the software.

The software feature set they purchased (based on what they bought).

The software provided by my company (based on my company name).

The software they purchased (based on their name).

The specific software copy they downloaded (based on the serial number).

Customer is emailed the unlock key that unlocks the following:.

If customer decides yes, then they purchase an unlock key from my website, providing me with the serial number of their copy of the software (or they download a new copy and purchase the key all at once).

Customer decides if they want to buy it or not.

Customer comes to my website and downloads the setup package as a free 30 day trial (by default, the software behaves in trial mode unless an unlock key is purchased and entered).

I wanted to provide the customer with the following scenario: I needed a quick way to sell a small, inexpensive WinForms application from my website either after the customer completes a free trial period, or when purchasing at download time. This is my first article posting to CodeProject.

Serial and keys unlock the world