Sony Corp announced it will begin restoring its PlayStation videogame network in Japan and in Asia. Over a month after a massive security breach leaked personal details on tens of millions of user’s accounts.

The company plans to testify before U.S. lawmakers at a hearing on data security in Washington on June 2 to address what is thought to be the biggest internet security breach in history.

Since hackers accessed personal information on 77 million PlayStation Network and Qriocity accounts, the Japanese electronics and entertainment giant has been under fire. In the security breach around 90% of users are in North America and Europe and it might possible hackers has been stolen their credit card information.

Security expert and video game fans have criticized Sony for its handling of the incident that sparked lawsuits and cast a shadow over its plans to combine the strengths of its content and hardware products via online services.

Sony apologized to its users for the outage and said a range of new security measures had been introduced. The new security included better early warning system that could alert the company about breaches.

Late on Thursday evening a new letter sent to U.S. lawmakers, Sony said it added more firewalls and introduced policy changes plus thorough testing of its systems. But the company warned the new measures might not be enough to make its network fully secure.

Sony said in the letter signed by Kazuo Hirai, the head of Sony Computer Entertainment, the company’s games unit, “No security system is absolutely foolproof, and changing conditions in the future can make a currently secure environment less secure.”

On Friday Japan’s trade ministry ordered the games unit to adopt measures to improve the management and security of personal information, following the data breach.

The ministry said in a statement, “Considering the content and volume of information leaked, it is an extremely grave incident, and it is truly regrettable that it occurred and took a considerable time to notify users and the ministry.”

In Asia the company will offer a new identity protection service to PlayStation users.

Company is targeting to restore all PlayStation Network services by the end of May.

The company has discovered unusual activity on its PlayStation Network that enables games console owners to download games chat with friends and pit their skills against rivals, on April 19.

Sony shut down the network and its Qriocity online music and movie service, annoying number of users, but waited almost a week before alerting users to the extent of the security leak.