re identifying securing files in article bb f c mash boulder co us rmashlan mash csn org robert mashlan writes tarnold vnet ibm com todd w arnold said in article almaden ibm com it s ok as long as you trust the end user to stay out of your application program or as long as it runs in a system where the user can t get to it otherwise you can t stop him from finding the load a module code in your program and simply bypassing the check for a valid module the devious user can either modify the object code before running the program or he can run the program under a debugger and change the instructions in memory there is a way to foil debuggers by clearing the single step interrupt on which a debugger depends every few instructions in the sensitive areas of the code this assumes the person is using the hardware debug instruction of an x type processor it can be negated by nop ing the clear debug instruction or by running the code on a machine simulator like one i wrote as a senior project in college it can bypass and trace practically anything one could write in software kind of like being on a star trek holideck kenneth ng please reply to ken eies njit edu for now all this might be an elaborate simulation running in a little device sitting on someone s table j l picard st tng
