Signing usually requires networking, but data transmission and networking operations cannot be carried out when the mobile phone is turned off, so the signer cannot sign through the mobile phone.

With the progress of electronicization, electronic signature has gradually become a convenient and fast signature method. Electronic signature refers to digital signature on electronic documents to achieve the same legal effect as physical signature. In the process of electronic signature, the signer needs to ensure the authenticity and validity of the signature through identity authentication and authorization. Electronic signature can not only improve the efficiency and convenience of signature, but also reduce the cost of signature and reduce the use of paper documents.