license-key

问题 License keys are the defacto-standard as an anti-piracy measure. To be honest, this strikes me as (in)Security Through Obscurity, although I really have no idea how license keys are generated. What is a good (secure) example of license key generation? What cryptographic primitive (if any) are they using? Is it a message digest? If so, what data would they be hashing? What methods do developers employ to make it difficult for crackers to build their own key generators? How are key generators

问题 I\'m currently involved in developing a product (developed in C#) that\'ll be available for downloading and installing for free but in a very limited version. To get access to all the features the user has to pay a license fee and receive a key. That key will then be entered into the application to \"unlock\" the full version. As using a license key like that is kind of usual I\'m wondering : How\'s that usually solved? How can I generate the key and how can it be validated by the application