Searching restricted documents in a cooperative search engine

Centralized search engines have difficulties retrieving fresh information. Thus, we developed a distributed search engine for intranets, named the cooperative search engine (CSE). In an intranet, each section of an organization has two sorts of documents; one public documents, the other private or secret documents. However, with the CSE, this simple security division was not considered; and we proposed a method to establish open and private documents, and to search them from inside of an organization in an integrated fashion.