 He figured that there was another component, which was XOR-ed with this, that did not always change with each new character, and that this was the product of a wheel that he called formula_21 ("psi"1).The same applied for each of the five impulses (formula_11formula_12formula_13formula_14formula_15 and formula_21formula_22formula_23formula_24formula_25).So for a single character, the whole key K consisted of two components