According to [41–43], , , and . : the number of -bit chunks in Waters scheme; : the number of registered users in Qin scheme; : the number of individual signatures; : the time cost of a pairing operation; : the time cost of a scalar multiplication in ; : the time cost of a map-to-point hash operation; : the time cost of a point addition operation; : the time cost of a modular multiplication in ; : the time cost of a hash operation; ROM: random oracle model; STD: standard model.