INFO: Extracting the SID from an ACE

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This article was previously published under Q102101

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SUMMARY

To access the security identifier (SID) contained in an access control entry (ACE), the following syntax can be used:

   PSID pSID;

   if((((PACE_HEADER)pTempAce)->AceType) == ACCESS_ALLOWED_ACE_TYPE)
   {
      pSID=(PSID)&((PACCESS_ALLOWED_ACE)pTempAce)->SidStart;
   }

MORE INFORMATION

The "if" statement checks the type of ACE, which is one of the following values:

   ACCESS_ALLOWED_ACE_TYPE
   ACCESS_DENIED_ACE_TYPE
   SYSTEM_AUDIT_ACE_TYPE

The conditional statement casts pTempAce (the pointer to the ACE) to a PACCESS_ALLOWED_ACE structure. The address of the SidStart member is then cast to a PSID and assigned to the pSID variable. pSID can now be used with any Win32 Security application programming interface (API) that takes a PSID as a parameter.