The full text chat messages of TOM-Skype users, along with Skype users who have communicated with TOM-Skype users, are regularly scanned for sensitive keywords, and if present, the resulting data are uploaded and stored on servers in China.
These text messages, along with millions of records containing personal information, are stored on insecure publicly-accessible web servers together with the encryption key required to decrypt the data.
The captured messages contain specific keywords relating to sensitive political topics such as Taiwan independence, the Falun Gong, and political opposition to the Communist Party of China.
Our analysis suggests that the surveillance is not solely keyword-driven. Many of the captured messages contain words that are too common for extensive logging, suggesting that there may be criteria, such as specific usernames, that determine whether messages are captured by the system.
While these conditions have been known for years, most Skype users are probably not aware of the differences between Tom Skype and the regular Skype. Many are running Tom Skype on their computers thinking that it's the regular Skype and trusting Microsoft to deal with their call and chat data confidentially.