10. A document presentation system, the document presentation system comprising: one or more processors; system memory; a document database; a search database; a document collection system, the document collection system configured to: collect documents from one or more data sources; tag documents, including for each collected document: tagging items in the document for which the document can be searched; and tagging portions of the document as eligible for alteration, based on classification of the portions, when presented to a user that does not have access to the entire document contents; store the tagged documents in a search database for use in generating search results that match received search requests; and store copies of collected documents in the document database for use in building altered representations of a collected document for a user that does not have access to the entire document contents; and a presentation engine, presentation engine configured to: determine how to alter search results that include tagged portions of a document tagged as eligible for alteration when a user does not have access to the tagged portions of the document based on an access policy; and build an altered representation of the document by replacing the tagged portions of the document with other data in accordance with the determination.
12. The system of claim 10 , the presentation engine further configured to: receive credentials from the user; present the credentials to a data source; and receive the access policy from the data source.