And yet in practice the only problem with them is when mapping Windows SID is needed. Otherwise, they are fine. Also, Windows SIDs are fixed-size 128 bit. They

And yet in practice the only problem with them is when mapping Windows SID is needed. Otherwise, they are fine. Also, Windows SIDs are fixed-size 128 bit. They were supposed to be GUIDs, but they are not that random; user SIDs contain common prefix from the domain SID.