how to add a digital signature to an xlsx file

Question

I am trying to add a digital signature to an xlsx file... Can't seem to find any resources for this (other than adding signatures to literal/regular xml files). Is this possible with docx4j? I see it includes jaxb-xmldsig but there are no samples that I could find. Perhaps someone could point me in the right direction?

EDIT: Per Jason, I looked at the differences via the demo webapp....

There are two new entries in [Content_Types].xml:

• <Default Extension="sigs" ContentType="application/vnd.openxmlformats-package.digital-signature-origin"/>
• <Override ContentType="application/vnd.openxmlformats-package.digital-signature-xmlsignature+xml" PartName="/_xmlsignatures/sig1.xml"/>

Two new parts within a new top level directory (_xmlsignatures):

• /_xmlsignatures/origin.sigs
• /_xmlsignatures/sig1.xml

There is also a _rels directory within _xmlsignatures which contains a single file origin.sigs.rels. I can post more info if that will be helpful.

Answer 1

It is not the DigSig from the extended properties ?

• see : http://www.schemacentral.com/sc/ooxml/e-extended-properties_Properties.html
• see : http://msdn.microsoft.com/en-us/library/documentformat.openxml.extendedproperties.properties_members(v=office.14).aspx (DigitalSignature)

• see : docx4j\xsd\docProps\shared-documentPropertiesExtended.xsd

  Digital Signature > contains a binary Blob

If it is, you can add the DigSig to the propertie by editing the extendPropertie

DocPropsExtendedPart docPropsExtPart = wordMLPackage.getDocPropsExtendedPart();
Properties extProp = docPropsExtPart.getContents();
ExtendedProperties.modifyProp(props.getExtendedProperties(), extProp);
wordMLPackage.setPartShortcut(docPropsExtPart, Namespaces.PROPERTIES_EXTENDED);