problem is that it is much more likely that two of your open circuits will fall into patterns GGC and CGG than it is that an individual circuit will fall into pattern CGC Tor devs are aware of this attack, they are going to research it further. One possible solution is to apply the circuit construction rules to ALL circuits rather than to individual circuits. Already you cannot use the same node at two positions on two different circuits, or two nodes from the same family on the same circuit for that matter. That said there are no rules regarding node selection across multiple circuits, and it is not rare to find that you have open circuits in the following pattern: GFG GGF or even more worrying, FGG GFG GGF Where F == a node that is either the same node, or from the same family of nodes.