Proposal of a method for protecting private information in user context

In a ubiquitous computing environment, people can obtain and transmit information anytime, anywhere. In this situation, a user's context plays a key role. Unfortunately, the ubiquitous environment introduces some problems. The first is ease of access to what users truly want. The second important problem is handling private information. In utilizing a ubiquitous environment, all of a user's context is held online, and applications may share them to propose advanced services. Therefore, a user's context is automatically transmitted or attached as metadata. The context, however, includes the user's private information. Therefore, we need a system that separates information into private and public elements and treats them differently. In view of this, we consider how to attach metadata and how to extract and protect transmitted private information, in the specific case of blog entries. We propose a method of protecting private information that expands the existing item definition format in the CaTaC platform. This method will support the establishment of new communication methods using blogs in the near future.