Chemical markup, XML, and the World-Wide Web. 3. Toward a signed semantic chemical web of trust

We describe how a collection of documents expressed in XML-conforming langu ages such as CML and XHTML can be authenticated and validated against digit al signatures which make use of established X.509 certificate technology. T hese can be associated either with specific nodes in the XML document or wi th the entire document. We illustrate this with two examples. An entire jou rnal article expressed in XML has its individual components digitally signe d by separate authors, and the collection is placed in an envelope and agai n signed. The second example involves using a software robot agent to acqui re a collection of documents from a specified URL, to perform various opera tions and transformations on the content, including expressing molecules in CML, and to automatically sign the various components and deposit the resu lt in a repository. We argue that these operations can used as components f or building what we term an authenticated and semantic chemical web of trus t.