Mobile phone users in Hong Kong may not be surprised to hear that one of the three most popular mobile-chat applications in Asia systematically censors politically-sensitive content and may also have network security flaws. A study by the University of Toronto's Citizen Lab, set up to research internet censorship, found that the Line messaging application (or "app") censors sensitive keywords on any account registered with a Chinese phone number - even when the user is located outside the mainland. Line is a Japanese proprietary application for the exchange of instant messages on smartphones and personal computers. The Canadian researchers also found that chat traffic sent over 3G networks was unencrypted in the application's global Android version at least as late as August 20, 2013, which potentially allows third parties to eavesdrop on private communications. "I am not very worried about using Line because I am aware that network security is limited and because of what I already know about censorship on [Chinese chat-app] WeChat," said Juniata Kwok. But Jo Mitchell, another Hong Kong resident, said she grew concerned when she learned that the Thai government had announced in August that it would conduct a surveillance of Line conversations to "ensure the rule of law, order and national security". "I told my friends in Thailand to stop using the app completely. It's a complete invasion of privacy and there's also the concern that conversations or jokes could be misunderstood, read out of context or twisted," she said. Line, produced by a Japanese subsidiary of South Korean internet giant Naver Corporation, has seen a rapid increase in its user base since its release in June 2011. It now has 300 million users in 230 countries globally and has the largest market share for messaging apps in Japan, Thailand, and Taiwan. Last December, the company launched a Chinese version of the app called Lianwo, in partnership with Chinese software firm Qihoo. A company spokesman said that Lianwo "is optimised for its local environment … in accordance with local standards and regulations," but denied that censorship functions were active in its global service. In Hong Kong, where mainland China's censorship regulations do not apply, Line is working with local partners including Circle K, Ocean Park, and Standard Chartered to expand its user base in the city, according to the spokesman. Citizen Lab researchers were able to identify lists of censored words in its analysis of two previous versions of the app, the first containing 223 blocked keywords and the second containing 370 blocked keywords. Words on the lists include references to the Bo Xilai scandal, the Tiananmen Square massacre and Falun Gong, as well as obscure references to little-known relatives of political leaders in China. Jeffrey Knockel, a researcher on web security issues at the University of New Mexico, said concerned users should be careful not to react to the news by switching from Line to another app that performs even more pervasive censorship or surveillance. "What's interesting is how these chat companies attempt to comply with Chinese regulations so differently. Some censor, some surveil, and some both," Knockel said. "And when we look at their blacklisted word lists, they have relatively few words in common, so wherever these companies are getting their words from, they don't seem to be from the government or even the same place." Mart van de Ven, founder of advocacy group Open Data Hong Kong, said users should also remember that violations of privacy are not unique to authoritarian states. "Just because countries like China or Thailand might have more stringent measures, this doesn't mean that similar things don't take place in the most 'liberal' countries in the world. "Reports like these reveal that breaches of our trust are more common than we'd like, so hopefully it will invigorate a broader interest in online privacy literacy," he said.