I have a visual basic application already built. It stores the users information into text files in the application directory. I have a small system in place that does a basic encryption on the files. It ecrypts and de-crytps as it loads and saves. The problem is that given a little time anyone could basically hack apart the text file and change the values in those files. It's not tough to figure it out. I need a iron clad way to continue to save and write to those files, but the files are hard-core protected and locked. There can be just about no way someone could open and manipulate them. The only way these should be open and modified is by the program. There should be nothing additional that a user would have to install, except maybe a dll or something. I AM OPEN TO SUGGESTIONS ON HOW TO SOLVE THIS PROBLEM! The solution should be simple, work basically the same as it does now, and with just slight modification - seriously lock, password-protect, or otherwise completely prevent those files from being manipulated by anyone or anything but the application itself when it loads and saves. There should also be something in place to keep the files from be copied to another users directory, ie, maybe checking the machine-name or serial numbers on the machine or something. I need a quick, simple, and easy to implement wat to do this. I am open to creative ideas to protect these files and the data inside.
Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. Complete copyrights to all work purchased.
WIndows9.X, XP, Win2K Visual Basic