I need a crypting method, that will convert a string into a crypted one. I searched the google and fount things like md5, but even a kid can breake it. I need a method in which I can insert some kind of a decrypting password, so that to write a function with a parameter of this password.
I know that there are this king of methods, but the idea is that the crypted string need to be short. For example if I crypt ten chars long string the crypted should be a maximum of 15-20 chars. I need this function in order to generate serial number that are made by a unique hardware ID and the period of time for which the program can be used. The serial number needs to be short in order to be dictated by the phone.