The government began a review of how to change a decades-old resident registration system to better protect personal information in the wake of last month's massive data leak, officials said Tuesday.

In January, some 20 million citizens' personal and financial data were found to have leaked from the country's major credit card companies, sparking a public outcry demanding a reform in the old and loose identification system.

"As part of efforts to better protect personal information, we've been reviewing the current resident registration number system," said an official of the Ministry of Security and Public Administration.

Currently, customers are required to tell their 13-digit registration number to identify themselves for financial services.

All Korean citizens have the unique number until death, which carries such personal information as their date of birth and sex.

Experts have also pointed out that the current plastic ID card, introduced some 15 years ago, is vulnerable to forgery or abuse. Back in 2010, the government had made a botched attempt to introduce a new electronic ID card to prevent forgery.

"With all possibilities open, we will seek ways on how to reform the system, including developing a new authentication ones," he added.

As an often-cited alternative to guarantee privacy, the government is mulling to introduce a new code with "random numbers" that do not infer any personal information.

The number would also be subject to change upon the request of each person, according to the ministry.

In a move to better protect privacy and prevent abuse of personal information, the ministry is considering strictly restaining the use of the national ID number in private sectors, including by financial institutions.

"It is problematic that the current ID system, which was developed for public affairs has been adopted by private sectors. They have to come up with their own system to identify individuals," another official said.

The government also decided to push to require all public and private entities to encode their customers' registration numbers, the ministry said.

As of last year, public institutions encrypted some 63.5 percent of the customers' data and private entities had 22.7 percent of the ID numbers encoded, according to government data. (Yonhap News)