How to read the Computer SID?

[StefanKittel]

Hello, to identify local machines I need to read the Computer SID. (like psgetsid.exe does) Does anybody have a bit of source for this? OS: Windows 2000 and up. Compiler: VC9 using MFC (not C#). But I'll take anything you have even VB or Delphy Mention: Computer SID, not a logon, user SID. Any computer have one. It don't need to be in a domain. I searched hours in google and forums. Thanks in advance Stefan

[Mark Salsbery]

From what I can find, the last 96 bits of HKEY_LOCAL_MACHINE\SECURITY\SAM\Domains\Account\V is the machine SID. Mark

Mark Salsbery Microsoft MVP - Visual C++ :java:

[StefanKittel]

Hello, on my computer Vista, no domain, the hive \\hklm\security is complete empty :-( \\hklm\sam\sam is empty too Stefan

[Mark Salsbery]

You have to enable viewing - by default (even if you're an administrator), you don't have read rights in the security key. You can give yourself permissions in regedit however. Anyway, I played around with this, and the following code gives me the same SID found in that registry hive (on Vista):

DWORD SIDLength = 0;
DWORD RefDomainNameLength = 0;
SID\_NAME\_USE SIDNameUse;
::LookupAccountName(NULL, \_T("MYCOMPUTERNAME\\\\"), NULL, &SIDLength, NULL, &RefDomainNameLength, &SIDNameUse);
PSID psid = (PSID)new BYTE\[SIDLength\];
LPTSTR domain = new TCHAR\[RefDomainNameLength\];
::LookupAccountName(NULL, \_T("MYCOMPUTERNAME\\\\"), psid, &SIDLength, domain, &RefDomainNameLength, &SIDNameUse);

//... use the SID (psid) here ...

// \*\* Test \*\*
LPTSTR StringSid;
::ConvertSidToStringSid(psid, &StringSid);
::LocalFree(StringSid);
// \*\* End Test \*\*

delete\[\] domain;
delete\[\] (BYTE\*)psid;

Mark Salsbery Microsoft MVP - Visual C++ :java:

modified on Saturday, August 30, 2008 11:45

[StefanKittel]

Hello, that looks great. I ignored LookupAccountName because, reading in the msdn, it should be only working with a PDC. I try this out. Thanks Stefan