Re: Relax permissions for reading hard drive serial number?

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On Dec 02, 2007, at 13:45:44, Matti Aarnio wrote:
This lack of having stable(*) unique system identifier available to applications is one of the small details that make node locked commercial software delivery challenging thing in UNIX environments..

*) "stable" as both stable data, and stable API to get it.

Well... There's that. There's also the fact that anybody with a modicum of ASM programming skills can get clever with GDB and traces from "Correct HW serial" and "Incorrect HW serial" can write a 10- line GDB script to make it work regardless. I did something similar with a popular FPS (which I legitimately own) on one of my Mac systems after having left the DVD behind when going to a LAN party. Addresses removed to protect the innocent^Wguilty, but they took maybe 15 minutes to acquire:

delete 1
set $r3 = 0

At some point every such "locked" computer program has code like this:
if (program_is_not_authorized()) {

All it takes for somebody with a debugger is to identify the last instruction of the "program_is_authorized()" function and change $r3 (or whatever return register your system uses) from a 1 to a 0. The fact remains that once the software is running on *THEIR* computer there is nothing you can practically do to forcibly prevent them from using it in whatever fashion they desire. Typically if you price your software reasonably people will be willing to pay for multiple copies but there are no foolproof technical measures to enforce that they do so.

Kyle Moffett

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