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Excel Workbook File Digital Signature Errors

Hello. I’ve been having a problem using digital signatures in Excel. If I sign a worksheet that contains “Offset” or “Cell” functions (maybe others), the file always opens with an “Invalid signature – This signed content or this signature have been modified” error. This occurs as soon as you reopen the file – even when the content hasn’t changed!

Note that I save the (2007) workbook normally; select Prepare/Add a Digital Signature from the Office menu, and sign using a valid certificate. The signature is applied and listed as a Valid Signature until I close and reopen the file. When I use this procedure on any other workbook the signature works fine (i.e., I don’t get this change error). It only happens on those with “Offset” or “Cell” functions

 Note I am sure that the contents (i.e., the data and formula) have not changed. Any help would be appreciated. Thanks.

Try saving it 97-2003, then add digital signature try re-opening the file and check.

Is the Offset function referring to an external data?

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Thanks for the response. 97-2003 worksheet had the same problem. Offset function is local only. The test function I used was: "=OFFSET(B1,1,1)".

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So anyone have any ideas why I’m seeing errors for these?

Unrelated to the cell function error I noted earlier (i.e., happens with any function), I have also observed that if you digitally sign a protected workbook (Protect Workbook/Protect Structures and Windows) you can also get a signature error: “Verification Error”. It may be related to having an unlocked cell, or changing cell properties. But in either case the workbook was saved prior to applying the signature.

Note that the Excel window must remain open after saving in order to apply the signature. If Excel is closed and the file reopened before applying the signature, I’ve got a “Your signature could not be added to the document…” error.

Anyway this is proving to be a major inconvenience for us (well the cell function issue, not the protected workbook one). Any help or information would be greatly appreciated.

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Last updated March 4, 2024 Views 1,504 Applies to: