Article ID: 826516 - View products that this article applies to.
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To confirm that a digitally signed Office document came from a trusted source, and that the document was not modified after it was digitally signed, view the document's digital signature. 2007 Office products and Office 2003 support digital signatures on documents.
When you receive a digitally signed document, it is a good idea to check the digital signature for authenticity. For performance reasons, Office does not automatically check the authenticity of a digital signature when you open a document. To determine whether a document has an authentic digital signature, follow these steps as appropriate:
2007 Office products
A valid certificate has the image of an unblemished certificate in its upper-right corner. A certificate with problems shows the image with a red X.
The following actions may cause a digital signature to become not valid:
A feature in Word 2003 informs you if there are signs of tampering with a digital signature. If there are signs of tampering, such as with a hexadecimal (hex) editor, you receive the following error message before the digital signature dialog opens:
For more information about digital signatures, see the Office Help documentation.
This document has been digitally signed but has been modified since it was signed. The digital signatures in this document will be removed if you click OK in the Digital Signature dialog.
To learn more about digital signatures and certificates, visit the following Microsoft Web sites:
Article ID: 826516 - Last Review: September 12, 2011 - Revision: 3.0