hello, i am currently writing a program and need to be able to store information to the local pc atfer each run of the program specific to the run. ie a count of time the times the program has been run. i could store this in a file but the user could reset the counter by copying an old version of the file and overwriting the current one at a later date. is there a secure way i can store this information so the user cannot change it(no matter how good of a hacker he is) but the program can? cheers

well not really sure what ya exactly want to do but you could do an exclusive or with a key and the info that your outputting and then when reading that in again you use the exclusive or again.

most simple cryptography or readup on a bit of cryptography

Surely there is not this is because..if something (for example, the program itself) can alter the file, then there is a way to alter the file and the problem is then to prevent any other user from using that way. And as you might guess, there is no way of doing this water-proof; if such a way existed (apart from not having the machine at all), we wouldn't need to worry about hackers or crackers. But we do.

You could set the bit who's-name-I-don't-remember, that prevents anybody from changing the file (was it "u-bit"?), and unset it while the program touches the file. This method, anyway, has the weakness that a mad hacker, a cracker, would only need to find a way to gain root privileges to breach your fine system. It might be difficult, but never impossible

basically, my problem is that anything i put in a file can be copied by the user. the problem i think i need to solve is can my program reliably detect if the user modified the file or the program did it. cheers