A cyberhacker claims to have obtained the personal data of 1 billion Chinese residents in what could be one of the largest data breaches in history. An anonymous user in a hacker forum using the handle “ChinaDan” offered to sell the large database last week for 10 bitcoin, worth about $200,000. The user said the data was obtained from an unsecured Shanghai police database and was publicly accessible for a year. The user claimed the database contained such personal information as names, addresses, birth dates, national identification numbers and extensive criminal records. U.S.-based cable news network CNN says it has...