To counter the effects of a recent massive data breach, South Korea is mulling issuing new national ID numbers to all 50 million of it citizens – a project that would cost the government an estimated $650 million.

Businesses would also have to contend with their own tremendous costs—in the billions, perhaps—associated with upgrading their systems to accommodate the new ID numbers. South Koreans use their resident registration numbers, first implemented in the 1960s, for a variety of tasks, according to an ABC News report. The digits include citizens' birth dates, a number indicating gender and other data.

The report quoted a researcher from the Korea Research Institute for Local Administration as saying the numbers are like “master keys” to hackers that could be used to “open every door and steal whole packages of personal information.”