Question

I’m looking for a way to extract the computer SID using Delphi code. There’s a tool called PsGetSid from SysInternals that does this, but I can’t use it in my application. I searched for a code example in Google and couldn’t find one.

How can I achieve this in Delphi?

Please help.

Answer 1

This is a sample using the LookupAccountName WinAPi function as @MikeKwan suggest.

{$APPTYPE CONSOLE}

uses
  Windows,
  SysUtils;


function ConvertSidToStringSid(Sid: PSID; out StringSid: PChar): BOOL; stdcall;  external 'ADVAPI32.DLL' name {$IFDEF UNICODE} 'ConvertSidToStringSidW'{$ELSE} 'ConvertSidToStringSidA'{$ENDIF};

function SIDToString(ASID: PSID): string;
var
  StringSid : PChar;
begin
  if not ConvertSidToStringSid(ASID, StringSid) then
    RaiseLastWin32Error;

  Result := string(StringSid);
end;

function GetLocalComputerName: string;
var
  nSize: DWORD;
begin
  nSize := MAX_COMPUTERNAME_LENGTH + 1;
  SetLength(Result, nSize);
  if not GetComputerName(PChar(Result), {var}nSize) then
  begin
    Result := '';
    Exit;
  end;

  SetLength(Result, nSize);
end;

function GetComputerSID:string;
var
  Sid: PSID;
  cbSid: DWORD;
  cbReferencedDomainName : DWORD;
  ReferencedDomainName: string;
  peUse: SID_NAME_USE;
  Success: BOOL;
  lpSystemName : string;
  lpAccountName: string;
begin
  Sid:=nil;
  try
    lpSystemName:='';
    lpAccountName:=GetLocalComputerName;

    cbSid := 0;
    cbReferencedDomainName := 0;
    // First call to LookupAccountName to get the buffer sizes.
    Success := LookupAccountName(PChar(lpSystemName), PChar(lpAccountName), nil, cbSid, nil, cbReferencedDomainName, peUse);
    if (not Success) and (GetLastError = ERROR_INSUFFICIENT_BUFFER) then
    begin
      SetLength(ReferencedDomainName, cbReferencedDomainName);
      Sid := AllocMem(cbSid);
      // Second call to LookupAccountName to get the SID.
      Success := LookupAccountName(PChar(lpSystemName), PChar(lpAccountName), Sid, cbSid, PChar(ReferencedDomainName), cbReferencedDomainName, peUse);
      if not Success then
      begin
        FreeMem(Sid);
        Sid := nil;
        RaiseLastOSError;
      end
      else
        Result := SIDToString(Sid);
    end
    else
      RaiseLastOSError;
  finally
    if Assigned(Sid) then
     FreeMem(Sid);
  end;
end;


begin
 try
   Writeln(GetComputerSID);
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;
end.