Using a digital signature

Excel lets you add a digital signature to a workbook. Using a digital signature is somewhat analogous to signing a paper document. A digital signature helps to assure the authenticity of the workbook and also ensures that the content has not been modified since it was signed.

After you sign a workbook, the signature is valid until you make changes and resave the file.

Getting a digital ID

In order to digitally sign a workbook, you must obtain a certificate from a certified authority who is able to verify the authenticity of your signature. Prices vary, depending on the certificate granting company. Another option is to create your own digital ID, but others will not be able to verify the authenticity. Creating your own digital ID is useful if you want to ensure that no one has tampered with one of your signed workbooks.