Many documents are from unknown sources, so security is not guaranteed. Office can use digital certificates to verify the reliability of the source. and digitally sign a file or macro with a digital certificate. In general, digital certificates are obtained from commercial certification authorities and internal security administrators or information technology professionals. Ordinary users can create digital signatures themselves using the Selfcert.exe tool (due to Selfcert.exe A digital certificate that you create yourself is not issued by a formal certification authority, and a macro scheme that uses this certificate to add a signature will be considered a self-signed scheme so that other users may not be able to run self-signed macros. Signing a macro with a digital certificate is simple: Open the file that contains the macro scheme you want to sign, and in the tools → macro →visual basic Editor → Project Explorer, select the scenario you want to sign. Then click the "tools → digital signature" command.