Click the area to be signed, and the list of digital certificates as shown below will pop up. Select the digital certificate you want to sign, and then click Continue and Sign to complete the signing. The Save dialog box will pop up, and you can save it. After completing all the areas in the document that need to be signed, click the "Submit" button in the upper right corner of the first page of the document to submit the document. At this point, the digital signature is completed. Digital signature technology encrypts abstract information with the sender's private key and sends it to the receiver together with the original text. The receiver can decrypt the encrypted digest information with only the transmitted public key, and then use a hash function to generate digest information for the received original text and compare it with the decrypted digest information. If they are the same, it means that the received information is complete and has not been modified during transmission, otherwise it means that the information has been modified, so the digital signature can verify the integrity of the information.