Fig. 2
Initialization 2: Step 3 – the user sends the polynomial A, the user identifier I D U , the verification key V K U , and the ToU to the CA. Step 4 – the CA sends the commitment C, the signature on the verification key (S i g CA (V K U )), and the signature on the ToU (S i g CA (T o U)) to the user. Step 5 – the user forwards the message received in Step 4 to the server