The transaction process of SET is very complicated. In the process of completing a transaction of S ET protocol, it is necessary to verify the electronic certificate 9 times, verify the digital signature 6 times, transfer the certificate 7 times, sign 5 times, and encrypt symmetrically and asymmetrically 4 times. Generally, it takes about 1.5-2 minutes or more to complete a SET protocol transaction. Due to the mixed network facilities in various places, it may take longer to complete the transaction process of a set of agreements. Simply put, limitation is a waste of time.