Hello,

I'm trying to secure my program with a serial key. Just like office or windows.

When I, i.e, have a code in the form xxxxx-xxxxx-xxxxx-xxxxx I could check if every xxxxx meets some rule, like divided by a certain number, but I think it's not safe enough.

An other option is to encrypt the code with TEA, SHA, DES or something like that. But in order to use these encryptfunctions you have to implement them in your program, else you cannot check if the key the user enters is correct. But if you do this people can reverse engineer the program and reveal the algorithm, or am I thinking to simple?

Does anyone have experience with this and wants to help me with this?