For old-school CD keys, it was just a matter of making up an algorithm for which CD keys (which could be any string) are easy to generate and easy to verify, but the ratio of valid-CD-keys to invalid-CD-keys is so small that randomly guessing CD keys is unlikely to get you a valid one. INCORRECT … Read more
When encrypting, you use their public key to write a message and they use their private key to read it. When signing, you use your private key to write message’s signature, and they use your public key to check if it’s really yours. I want to use my private key to generate messages so only … Read more
You can do something like create a record which contains the data you want to authenticate to the application. This could include anything you want – e.g. program features to enable, expiry date, name of the user (if you want to bind it to a user). Then encrypt that using some crypto algorithm with a … Read more
Caveat: you can’t prevent users from pirating, but only make it easier for honest users to do the right thing. Assuming you don’t want to do a special build for each user, then: Generate yourself a secret key for the product Take the user’s name Concatentate the users name and the secret key and hash … Read more