registration codes-license expiration date

[bdaniel]

I have put together a form for the user to enter a registration code and a subroutine to check for the expiration date to control access to a program. The correct data is kept in two .txt files. Works fine, but now I realize that the .txt files can be compromised and my "security" wont be that effective. I can hide the files for some protection, also work with the permissions on the files, but wondering if anyone has a better way of programming in registration code and using expiration dates to control access to a program?

[pdebaets]

We have a product called KeyedAccess that will handle this for you, but you may want to consider encrypting the data in your text files and/or including a check digit. A simple character substitution encryption may work for your needs, and check digit calculation algorithms are available on the web.

[Mclaren]

you can also hard code the registration fields into an access module.

When the expiration date comes along, a warning is shown. User is told to contact you for new code.

Use a check digit calculation algorithm as mentioned above to create and validate new codes.