diff --git a/reactos/lib/advapi32/advapi32.def b/reactos/lib/advapi32/advapi32.def
index 34bfc17c4c2..80f3776c1be 100644
--- a/reactos/lib/advapi32/advapi32.def
+++ b/reactos/lib/advapi32/advapi32.def
@@ -1,4 +1,4 @@
-; $Id: advapi32.def,v 1.20 2004/07/10 14:38:23 weiden Exp $
+; $Id: advapi32.def,v 1.21 2004/08/23 21:16:25 gvg Exp $
 ;
 ; advapi32.def
 ;
@@ -47,6 +47,8 @@ ChangeServiceConfigW@44
 ;CloseEventLog@4
 CloseServiceHandle@4
 ControlService@12
+ConvertSidToStringSidA@8
+ConvertSidToStringSidW@8
 CopySid@12
 ;CreatePrivateObjectSecurity@24
 CreateProcessAsUserA@44
diff --git a/reactos/lib/advapi32/advapi32.edf b/reactos/lib/advapi32/advapi32.edf
index 180ba865a45..f08749665ec 100644
--- a/reactos/lib/advapi32/advapi32.edf
+++ b/reactos/lib/advapi32/advapi32.edf
@@ -1,4 +1,4 @@
-; $Id: advapi32.edf,v 1.40 2004/07/10 14:38:23 weiden Exp $
+; $Id: advapi32.edf,v 1.41 2004/08/23 21:16:25 gvg Exp $
 ;
 ; advapi32.edf
 ;
@@ -44,6 +44,8 @@ ClearEventLogW=ClearEventLogW@8
 CloseEventLog=CloseEventLog@4
 CloseServiceHandle=CloseServiceHandle@4
 ControlService=ControlService@12
+ConvertSidToStringSidA=ConvertSidToStringSidA@8
+ConvertSidToStringSidW=ConvertSidToStringSidW@8
 CopySid=CopySid@12
 ;CreatePrivateObjectSecurity=CreatePrivateObjectSecurity@24
 CreateProcessAsUserA=CreateProcessAsUserA@44
diff --git a/reactos/lib/advapi32/advapi32.h b/reactos/lib/advapi32/advapi32.h
index cb1c067ef6b..207820132db 100644
--- a/reactos/lib/advapi32/advapi32.h
+++ b/reactos/lib/advapi32/advapi32.h
@@ -6,4 +6,5 @@
 #define NTOS_MODE_USER
 #include <ntos.h>
 #include <windows.h>
+#include <sddl.h>
 #include <rosrtl/string.h>
diff --git a/reactos/lib/advapi32/sec/sid.c b/reactos/lib/advapi32/sec/sid.c
index 3b452158e47..112d24f7ebb 100644
--- a/reactos/lib/advapi32/sec/sid.c
+++ b/reactos/lib/advapi32/sec/sid.c
@@ -1,4 +1,4 @@
-/* $Id: sid.c,v 1.14 2004/08/15 17:03:15 chorns Exp $
+/* $Id: sid.c,v 1.15 2004/08/23 21:16:26 gvg Exp $
  *
  * COPYRIGHT:       See COPYING in the top level directory
  * PROJECT:         ReactOS system libraries
@@ -210,4 +210,97 @@ IsValidSid (PSID pSid)
   return (BOOL)RtlValidSid (pSid);
 }
 
+/*
+ * @implemented
+ */
+BOOL STDCALL
+ConvertSidToStringSidW(PSID Sid, LPWSTR *StringSid)
+{
+  NTSTATUS Status;
+  UNICODE_STRING UnicodeString;
+  WCHAR FixedBuffer[64];
+
+  if (! RtlValidSid(Sid))
+    {
+      SetLastError(ERROR_INVALID_SID);
+      return FALSE;
+    }
+
+  UnicodeString.Length = 0;
+  UnicodeString.MaximumLength = sizeof(FixedBuffer);
+  UnicodeString.Buffer = FixedBuffer;
+  Status = RtlConvertSidToUnicodeString(&UnicodeString, Sid, FALSE);
+  if (STATUS_BUFFER_TOO_SMALL == Status)
+    {
+      Status = RtlConvertSidToUnicodeString(&UnicodeString, Sid, TRUE);
+    }
+  if (! NT_SUCCESS(Status))
+    {
+      SetLastError(RtlNtStatusToDosError(Status));
+      return FALSE;
+    }
+
+  *StringSid = LocalAlloc(LMEM_FIXED, UnicodeString.Length + sizeof(WCHAR));
+  if (NULL == *StringSid)
+    {
+      if (UnicodeString.Buffer != FixedBuffer)
+        {
+          RtlFreeUnicodeString(&UnicodeString);
+        }
+      SetLastError(ERROR_NOT_ENOUGH_MEMORY);
+      return FALSE;
+    }
+
+  MoveMemory(*StringSid, UnicodeString.Buffer, UnicodeString.Length);
+  ZeroMemory((PCHAR) *StringSid + UnicodeString.Length, sizeof(WCHAR));
+  if (UnicodeString.Buffer != FixedBuffer)
+    {
+      RtlFreeUnicodeString(&UnicodeString);
+    }
+
+  return TRUE;
+}
+
+
+/*
+ * @implemented
+ */
+BOOL STDCALL
+ConvertSidToStringSidA(PSID Sid, LPSTR *StringSid)
+{
+  LPWSTR StringSidW;
+  int Len;
+
+  if (! ConvertSidToStringSidW(Sid, &StringSidW))
+    {
+      return FALSE;
+    }
+
+  Len = WideCharToMultiByte(CP_ACP, 0, StringSidW, -1, NULL, 0, NULL, NULL);
+  if (Len <= 0)
+    {
+      LocalFree(StringSidW);
+      SetLastError(ERROR_NOT_ENOUGH_MEMORY);
+      return FALSE;
+    }
+  *StringSid = LocalAlloc(LMEM_FIXED, Len);
+  if (NULL == *StringSid)
+    {
+      LocalFree(StringSidW);
+      SetLastError(ERROR_NOT_ENOUGH_MEMORY);
+      return FALSE;
+    }
+
+  if (! WideCharToMultiByte(CP_ACP, 0, StringSidW, -1, *StringSid, Len, NULL, NULL))
+    {
+      LocalFree(StringSid);
+      LocalFree(StringSidW);
+      return FALSE;
+    }
+
+  LocalFree(StringSidW);
+
+  return TRUE;
+}
+
 /* EOF */
diff --git a/reactos/w32api/include/sddl.h b/reactos/w32api/include/sddl.h
new file mode 100644
index 00000000000..10ab1659571
--- /dev/null
+++ b/reactos/w32api/include/sddl.h
@@ -0,0 +1,23 @@
+#ifndef _SDDL_H
+#define _SDDL_H
+#if __GNUC__ >=3
+#pragma GCC system_header
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+BOOL WINAPI ConvertSidToStringSidA(PSID Sid, LPSTR *StringSid);
+BOOL WINAPI ConvertSidToStringSidW(PSID Sid, LPWSTR *StringSid);
+
+#ifdef UNICODE
+#define ConvertSidToStringSid ConvertSidToStringSidW
+#else /* UNICODE */
+#define ConvertSidToStringSid ConvertSidToStringSidA
+#endif /* UNICODE */
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* ! defined _SDDL_H */