How to change/set a user SID?

[groovemonster]

Can someone tell me the best way to do the following:

Lookup a user SID, before I format.

And restore/change/set a user SID after I reinstall windows.

I need to reinstall WinXP Pro and don't want to lose the user SID.

Please help!

[John Veteran]

afaik, you can't set an SID. you can read one, i know there is a better way than this, but they are listed in the HKEY_USERS part of the registry. what do you need to do that requires you to have the same SID?

[Aaron P]

A user SID is made up in part from the SID of the machine where the user account exists which is uniquely generated at installation time, therefore you will not be able to make the user's SID the same when you reload the box. (There are exeptions to this which use well know SID (i.e. the same on every box), Administrator is and example of this)

However if you are doing this because you have files with security applied that you want to access after you reload the box, you can take ownership of the files after installation and reset permissions.

If on the other hand you have encrypted the files, you will not be able to get to them at all if you reinstall, de-encrypt the files first.

[groovemonster]

I have software that encodes its database with the user sid, therefore to open it after format I need to use the same sid.

so if I change the machine sid before creating new accounts this should work right. as windows always starts at the same number, see example. X = machine sid, right?

S-X-X-XX-XXXXXXXXXX-XXXXXXXXXX-XXXXXXXXXX-1003

I have found a tool called NewSID (www.sysinternals.com), to change the machine sid.

Does anyone know how good this tool is?