S on receiving the encrypted decision values di from all users Ui=1···p, computes d =
DECH(d1 × · · · × dp). If d > 0, abort tk; else S re-encrypts the corresponding cj values
and returns them to Ak: {ai j = RENC(rkUi→Ak , cj)|i = 1 · · · p, j = 1 · · ·m}.