"Sony knows how - but not who - hacked into its PlayStation Network last month in possibly the biggest Internet security breach in history. And despite beefing up its system to prevent another cyberattack like the one that exposed the personal information of 100 million users, Sony can't guarantee that it won't happen again. In a letter sent this week to members of Congress, the Japanese tech giant said it boosted security measures through added firewalls, new policy changes and increased monitoring of its PlayStation and Qriocity systems.

"After just over three weeks of downtime resulting from the hacker attack on its online services, Sony started the process of turning the PlayStation Network back online late Saturday afternoon. In a video message, Sony president Kaz Hirai explained that the restoration process will take place in phases, the first of which is now underway around the world. Here's what will be coming back online:"

"Yesterday, in a letter to Congress, Sony detailed the steps they were taking to resolve the issues that have been plaguing them since the PlayStation Network and SOE online components were hacked, claiming to have found evidence linking the crime to Anonymous. Now, Anonymous has responded."

"Sony has said the that the hackers who stole more than 100 million users' personal details from its online gaming systems left a file implicating Anonymous, the internet activist collective. In a detailed letter about the security breach to a US Congressional committee, Kazuo Hirai, chairman of the electronics giant, said the the file discovered by investigators was named "Anonymous" with the words "We are Legion", part of the Anonymous motto.

"Thank you for your patience while we work to resolve the current outage of PlayStation Network & Qriocity services. The following email has been sent to all PSN registrants; please read the help and support FAQ for more information. Valued PlayStation Network/Qriocity Customer:

"Satoshi Fukuoka, a spokesman for Sony Computer Entertainment in Tokyo, spoke with PCWorld and claimed the company "has not yet determined if the personal information or credit card numbers of users have been compromised, but that Sony would promptly inform users if it found that was the case." Since you can't play your games online, why not use that extra time to double-check your credit and debit card records?"

"Users of Sony’s PlayStation Network remain offline for the fifth day running as the company scrambles to strengthen its network infrastructure before switching PSN back on. By close of business on Friday, Sony had yet to offer any explanation as to why PSN was down. However, at around 7:30 p.m. the company updated to say that an ‘external intrusion’ on its system had affected PSN and Qriocity services and that these had been switched off on the evening of April 20 (last Wednesday) pending an investigation into the issue."