Information leakage by way of paper documents has become such a serious matter that manufacturers of multifunction printers are providing a log capture device that captures document images whenever those printers are used. They are also offering a text search engine based on OCR text extraction from captured images. Since the accuracy rate of OCR is limited, this paper proposes a system increasing the accuracy of text searches in logs acquired in multifunction printers by numbering each page of paper documents and linking those ID numbers to the text data extracted from the original digital files. Experimental results show that this increases the accuracy rate of text searches from 52.4% to 98.0%.

In this paper we give a new signature algorithm that allows for controlled changes to the signed data. The change operations we study are removal of subdocuments (redaction), pseudonymization, and gradual deidentification of hierarchically structured data. These operations are applicable in a number of practically relevant application scenarios, including the release of previously classified government documents, privacy-aware management of audit-log data, and the release of tables of health records. When applied directly to redaction, our algorithm improves on [18] by reducing significantly the overhead of cryptographic information that has to be stored with the original data.

Information leakage through paper documents is not to be overlooked because it accounts for 43.8% of all the leakage in Japan. Most vendors of digital copiers are therefore offering new models equipped with additional security functions. Third-parties wanting to add security functions to copiers already used in their offices, however, need to know the copier specifications that the copier manufactures want to keep secret. In this paper we introduce our idea that enables a third party to control digital copiers. An application that enables us to monitor copying is also described.