Effectiveness
Standard key generation, where product keys are generated mathematically, is not completely effective in stopping copyright infringement of software, as these keys can be distributed. The overall effectiveness of product keys in enforcing software copyrights requires further study. In addition, with improved communication from the rise of the Internet, more sophisticated attacks on Keys such as cracks (removing the need for a key) and CD key generators have become common.
Because of this, software publishers are increasingly turning to alternative methods of verifying that keys are both valid and uncompromised. One method, product validation, assigns a product key based on a unique feature of the purchaser's computer hardware (such as its MAC address), which cannot be as easily duplicated since it depends on the user's hardware. Other newer methods may involve requiring periodical validation of the CD key with an internet server (for games with an online component, such as Battle.net, this is done whenever the user signs in). The validation can then be performed on the server side, preventing cracks tampering with it (as they do on the client side). The server can also keep a blacklist of all CD keys known to be invalid or which have explicitly been banned, and deny them access.
Read more about this topic: Product Key