This example demonstrates the ability to add multiple signatures to a single Office 2013 document.
In addition to the digital signature, the signer of the document can add a graphic of her actual signature, or use a Tablet PC to actually write a signature into the signature line in the document.
Digital signature warning for documents originally signed in Office 2003 or earlier versions.
Also, if you use XAd ES for a digital signature in Office 2013, the digital signature will not be compatible with Office 2010 or 2007 Office system unless you configure the Group Policy setting, Do not include XAd ES reference object in the manifest, and set it to Enabled.
This Group Policy setting is located under User Configuration\Administrative Templates\Microsoft Office 2013\Signing.
After you change this setting to Enabled, the Office 2013 applications use the Office 2003 binary format to apply digital signatures to Office 97–2003 binary documents that you created in Office 2013.
This article includes digital signature registry keys that are new to Office 2013.
In addition, Office 2013 has support for XAd ES (XML Advanced Electronic Signatures).
Each person who receives your signed document must manually decide whether to trust your certificate.
For larger organizations, two primary methods for obtaining digital certificates are available: certificates that are created by using an organization or corporation PKI and commercial certificates.
Organizations that want to share signed documents only among other employees in the organization might prefer a corporate PKI to reduce costs.
Organizations that want to share signed documents with people outside their organization might prefer to use commercial certificates.