With privacy concerns and the threat of surveillance from the likes of the NSA, more and more people are turning to the dark web and Tor. The anonymous, encrypted network has become a haven for not just illegal activity, but also for those who simply don’t want what they do online to be tracked and traced.

But now the Tor Project has voiced concerns that CDN and DDoS protection service CloudFlare is monitoring Tor traffic by introducing CAPTCHAs and cookies. CloudFlare is not alone: similar accusations are levelled at Google and Yahoo which are described as 'larger surveillance companies'. Concerns about interference with Tor traffic have been raised by project administrators in a ticket entitled "Issues with corporate censorship and mass surveillance".

Following instances of malicious traffic originating from the Tor network, CloudFlare introduced CAPTCHAs to ensure that visits to certain sites were being instigated by humans. This has not only proved irritating, but also unreliable. CAPTCHAs have been found to frequently fail, and appear multiple times. But more concerning that it opens up the potential for users to be "tagged, tracked and potentially deanonymized".

In a post on the Tor Project website, user ioerror says:

There are companies - such as CloudFlare - which are effectively now Global Active Adversaries. Using CF as an example - they do not appear open to working together in open dialog, they actively make it nearly impossible to browse to certain websites, they collude with larger surveillance companies (like Google), their CAPTCHAs are awful, they block members of our community on social media rather than engaging with them and frankly, they run untrusted code in millions of browsers on the web for questionable security gains. It would be great if they allowed GET requests - for example - such requests should not and generally do not modify server side content. They do not do this - this breaks the web in so many ways, it is incredible. Using wget with Tor on a website hosted by CF is... a disaster. Using Tor Browser with it - much the same. These requests should be idempotent according to spec, I believe. I would like to find a solution with Cloudflare - but I'm unclear that the correct answer is to create a single cookie that is shared across all sessions - this effectively links all browsing for the web. When tied with Google, it seems like a basic analytics problem to enumerate users and most sites visited in a given session.

There are concerns about CloudFlare's apparent lack of transparency, although an employee for the company did get involved in the discussion. ioerror continues:

One way - I think - would be to create a warning page upon detection of a CF edge or captcha challenge. This could be similar to an SSL/TLS warning dialog - with an option for users to bypass, engage with their systems or an option to *contact them* or the *site's owners* or to hit a cached version, read only version of the website that is on archive.org, archive.is or other caching systems. That would ensure that *millions* of users would be able to engage with informed consent before they're tagged, tracked and potentially deanonymized. TBB can protect against some of this - of course - but when all your edge nodes are run by one organization that can see plaintext, ip addresses, identifiers and so on - the protection is reduced. It is an open research question how badly it is reduced but intuitively, I think there is a reduction in anonymity. It would be great to find a solution that allows TBB users to use the web without changes on our end - where they can solve one captcha, if required - perhaps not even prompting for GET requests, for example. Though in any case - I think we have to consider that there is a giant amount of data at CF - and we should ensure that it does not harm end users. I believe CF would share this goal if we explain that we're all interested in protecting users - both those hosting and those using the websites.

There are no denials that the Tor network -- thanks largely to the anonymity it offers -- is used as a platform for launching attacks, hence the need for tools such as CloudFlare. As well as the privacy concerns associated with CloudFlare's traffic interception, Tor fans and administrators are also disappointed that this fact is being used as a reason for introducing measures that affect all users.

Ideas are currently being bounced around about how best to deal with what is happening, and one of the simpler suggestions that has been put forward is adding a warning that reads "Warning this site is under surveillance by CloudFlare" to sites that could compromise privacy.

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