CA

The new CA is a modification of Fredkin's earlier SALT architecture in which every cell is identified as either even or odd - as in sodium and chlorine in a salt crystal hence the name. The state of each cell is either up or down and the development rule simple takes account of states of odd and even neighbours. The up-date at each time step simply takes the form of a swap of the states of diagonally related cells. SALT CAs are reversible and capable of universal computation and are conjectured to be capable of universal construction in the sense of Von Neumann.

Well-designed CAs will create a trust hierarchy, which consists of a root with a number of subroots, to further enhance protection of the private key.