Electronic invoice is a comprehensive form of digital invoice. Compared with the traditional paper invoice, it no longer exists in paper form, but is stored and transmitted in the form of electronic files. Electronic invoice contains basic information of invoice, such as invoice code, invoice number, invoice date, information of buyers and sellers, detailed information of goods or services, amount, etc. Electronic invoices can be sent to the buyer by e-mail, SMS, e-commerce platform, etc. Can also be stored in the electronic invoice management system for internal use and management of enterprises. The use of electronic invoices can improve the efficiency of invoice management, reduce the cost of using and keeping paper invoices, and facilitate the inspection and verification of invoices. Electronic signature is a kind of electronic signature for electronic documents through cryptographic technology. Different from the traditional handwritten signature or seal, it is not a simple digital image. Electronic signature uses cryptographic technology to identify the identity of the signer and ensure the signer's approval of the document content.