If you share an Excel document with other people, there is a risk that the Excel document will be edited. If you want to make sure that the document has not been edited, you can add a digital signature to the Excel document.
You guarantee the integrity and authenticity of the Excel document with a digital signature. When the document is signed, a hash value is generated that identifies the document and associates the signature with the document. If the document is modified after it has been signed, the hash value will change and the digital signature will be invalidated.
Add digital signature to Excel document
There are two ways to add a digital signature to an Excel document. The first way is via a visible signature, text with a logo, for example, and the second way is invisible.
Add digital signature with text and logo
To get started, open Excel. Make sure the document has been saved at least once. Then click on “Text” > “Signature Line” > “Microsoft Office-signature line.
In the signature settings, first enter the name of the signer, the position of the signer, the email address and any instructions for the signer.
A digital signature is now added to the Excel document. If you do not yet have a digital ID, you must first purchase it through a partner. Read more about a digital ID here.
If you have a digital ID, double-click on the digital signature in the document. Then you can add an image to it.
Add invisible digital signature
The second way to add a signature is with an invisible signature.
An invisible digital signature is created using a digital certificate issued by a trusted certification authority (CA).
The digital signature is calculated based on the contents of the Excel document and is stored in a way that is not visible to the user. When the file is opened, the digital signature is automatically verified to ensure that the contents of the file have not been tampered with and that the signature is still valid.
Open Excel. In the menu, click “File” > “Info” > “Protect Workbook”. Then select the option “Add digital signature”.
As described, you also need a digital ID here. Click on the hyperlink at the top of the previous chapter for more information on how to apply for a digital ID.
I hope this helped you. Thank you for reading!