So we based security on trusting Mike with everything while each of us knew only what he had to know. Take that tree of names and numbers. I knew only party names of my cellmates and of three directly under me; was all I needed. Mike set up party names, assigned phone number to each, kept roster of real names versus party names. Let’s say party member "Daniel" (whom I would not know, being a "D" two levels below me) recruits Fritz Schultz. Daniel reports fact but not name upwards; Adam Selene calls Daniel, assigns for Schultz party name "Embrook," then phones Schultz at number received from Daniel, gives Schultz his name Embrook and emergency phone number, this number being different for each recruit.