It seems not a day passes without news on leakage of confidential information from governmental and other entities onto the Internet. The types of information leaked are vast and the content is critical -- Self-Defense Forces-related documents, quake-resistance data for nuclear-power plants, access codes for restricted areas at airports, police investigation records, the names of sex-crime victims, personal information on as many as 10,000 convicts, data on hospital patients, information on customers of private firms, and so forth.

The main culprit is the peer-to-peer file-sharing software Winny. To be exact, the real culprits are a virus that infects Winny and people who are careless when using their Winny-enabled privately owned computer for official work.

The leaks have been occurring for a long time but the government became serious about the Winny problem only after it was found in late February that the Maritime-Self Defense Force-related data had leaked from a private-use computer of a non-com communication officer aboard the destroyer Asayuki, deployed at Sasebo base in Nagasaki Prefecture. The leak included the telephone and fax numbers of more than 100 MSDF ships, a table of random numbers to read special reports on combat exercises and a roster of MSDF members.