So there is this software. When installed it somehow (probably reads file or registry entry) recognizes my windows operating system.
It's supposed to do some tasks only once per unique computer. If I uninstall the program and re install it, the software remembers that it has been installed and therefore do not do the task.
If I use system restore, software also does not do the tasks. If I load image of the system before the install, software also doesn't do the tasks.
If I re install a fresh copy of windows, then only the software does the task. IP even does not matter. Everything is the same, except it is a brand new copy of Windows operating system.
So I guess that the software reads some kind of unique operating system identifier, then connects to server to create a user profile.
So the question is? What could be those files which software uses to check system identifier? So far I have found out that there are entries under registry. WindowsNT/CurrentVersion and Windows/Cryptography but software do not rely on them.
Where else should I search? Any software which could help me find out?
Maybe it's reading the ProductId value from the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion.
Microsoft says:
The product key also forms the basis for the product ID that is created when Windows XP is installed. Each licensed instance of Windows XP has a unique Product ID.
You can use FileMon and RegMon by SysInternals to check what files and keys in registry are being accessed
Take care, for some OEM smopuiM versions, there is only one licensed instance of Windows XP. So you can find the same product ID for two PC.
来源：https://stackoverflow.com/questions/6536688/windows-unique-identifier