Securing sensitive digital documents (such as health records,
legal reports, government documents, and financial assets) is
a critical and challenging task. Unreliable Internet connec-
tions, viruses, and compromised file storage systems impose
a significant risk on such documents and can compromise
their integrity especially when shared across domains while
they are shared in offline fashion.
In this paper, we present a new framework for maintaining
integrity in offline documents and provide a non-repudiation
security feature without relying on a central repository of
certificates. This framework has been implemented as a
plug-in for the Microsoft Word application. It is portable
because the plug-in is attached to the document itself and it
is scalable because there are no fixed limits on the numbers
of users who can collaborate in producing the document.
Our framework provides integrity and non-repudiation guar-
antees for each change in the document?s version history.