Abstract This paper considers online news censorship and it concentrates on censorship of identities. Obfuscating identities may occur for disparate reasons, from military to judiciary ones. In the majority of cases, this happens to protect individuals from being identified and persecuted by hostile people. However, being the collaborative web characterised by a redundancy of information, it is not unusual that the same fact is reported by multiple sources, which may not apply the same restriction policies in terms of censorship. Also, the proven aptitude of social network users to disclose personal information leads to the phenomenon that comments to news can reveal the data withheld in the news itself. This gives us a mean to figure out who the subject of the censored news is. We propose an adaptation of a text analysis approach to unveil censored identities. The approach is tested on a synthesised scenario, which however resembles a real use case. Leveraging a text analysis based on a context classifier trained over snippets from posts and comments of Facebook pages, we achieve promising results. Despite the quite constrained settings in which we operate – such as considering only snippets of very short length – our system successfully detects the censored name, choosing among 10 different candidate names, in more than 50 of the investigated cases. This outperforms the results of two reference baselines. The findings reported in this paper, other than being supported by a thorough experimental methodology and interesting on their own, also pave the way for further investigation on the insidious issues of censorship on the web.
The issue of censorship on the Web has been faced from different perspectives: in the early 2000's, some information leakage was already possible to circumvent national censorship @cite_29 @cite_8 . In this work, we specifically consider censored texts. Work in @cite_3 proposes a method to make textual documents resilient to censorship sharing them over a P2P network, one of the most frequently used decentralised sharing mechanism. However, when considering centralised systems, like Facebook, censorship might occur on document instances (i.e., posts and comments). Thus, strategic information may be altered - or censored- by malicious users of P2P networks, as well as by authors of single posts on social media.
@cite_29 @cite_3 @cite_8
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Over the years, the Internet has democratized the flow of information. Unfortunately, in parallel, authoritarian regimes and other entities (such as ISPs) for their vested interests have curtailed this flow by partially or fully censoring the web. The policy, mechanism, and extent of this censorship varies from country to country. We present the first study of the cause, effect, and mechanism of web censorship in Pakistan. Specifically, we use a publicly available list of blocked websites and check their accessibility from multiple networks within the country. Our results indicate that the censorship mechanism varies across websites: some are blocked at the DNS level while others at the HTTP level. Interestingly, the government shifted to a centralized, Internet exchange level censorship system during the course of our study, enabling our findings to compare two generations of blocking systems. Furthermore, we report the outcome of a controlled survey to ascertain the mechanisms that are being actively employed by people to circumvent censorship. Finally, we discuss some simple but surprisingly unexplored methods of bypassing restrictions. We offer the first large scale, multiple source analysis of the outcome of what may be the most extensive effort to selectively censor human expression ever implemented. To do this, we have devised a system to locate, download, and analyze the content of millions of social media posts originating from nearly 1,400 different social media services all over China before the Chinese government is able to find, evaluate, and censor (i.e., remove from the Internet) the subset they deem objectionable. Using modern computer-assisted text analytic methods that we adapt to and validate in the Chinese language, we compare the substantive content of posts censored to those not censored over time in each of 85 topic areas. Contrary to previous understandings, posts with negative, even vitriolic, criticism of the state, its leaders, and its policies are not more likely to be censored. Instead, we show that the censorship program is aimed at curtailing collective action by silencing comments that represent, reinforce, or spur social mobilization, regardless of content. Censorship is oriented toward attempting to forestall collective activities that are occurring now or may occur in the future—and, as such, seem to clearly expose government intent. The Internet has traditionally been the most free medium for publishing and accessing information. It is also quickly becoming the dominant medium for quick and easy access to news. It is therefore not surprising that there are significant efforts to censor certain news articles or even entire web sites. For this reason, it is paramount to try to detect what is censored and by whom. In this paper we present the design and implemention of a web censorship monitor, called CensMon. CensMon is distributed in nature, operates automatically and does not rely on Internet users to report censored web sites, can differentiate access network failures from possible censorship, and uses multiple input streams to determine what kind of censored data to look for. Our evaluation shows that CensMon can successfully detect censored content and spot the filtering technique used by the censor. We present results from measurements of the filtering of HTTP HTML responses in China, which is based on string matching and TCP reset injection by backbone-level routers. This system, intended mainly for Internet censorship, is a national-scale filter based on intrusion detection system (IDS) technologies. Our results indicate that the Chinese censors discontinued this HTML response filtering for the majority of routes some time between August 2008 and January 2009 (other forms of censorship, including backbone-level GET request filtering, are still in place). In this paper, we give evidence to show that the distributed nature of this filtering system and the problems inherent to distributed filtering are likely among the reasons it was discontinued, in addition to potential traffic load problems. When the censor successfully detected a keyword in our measurements and attempted to reset the connection, their attempt to reset the connection was successful less than 51 of the time, due to late or out-of-sequence resets. In addition to shedding light on why HTML response filtering may have been discontinued by the censors, we document potential sources of uncertainty, which are due to routing and protocol dynamics, that could affect measurements of any form of censorship in any country. Between a single client IP address in China and several contiguous server IP addresses outside China, measurement results can be radically different. This is probably due to either traffic engineering or one node from a bank of IDS systems being chosen based on source IP address. Our data provides a unique opportunity to study a national-scale, distributed filtering system.