So for the past three months I’ve been using Tor Browser to surf the Web, not as a primary browser, but as a secondary browser. Firefox is my primary browser.

Together with using StartPage as my search engine, I feel much better about my privacy while surfing the Internet. Using Tor Browser leads to a tad slower browsing experience, but I knew that going in, so no complaints there.

So what did I learn from these past few months of using Tor Browser?

First: That some website’s will attempt to extract HTML5 canvas image data that can be used to uniquely identify my computer – even if they are disallowed from setting cookies. And it’s not just the “bad” sites. Reputable news organizations like The Guardian will attempt to.

Tor Browser HTML5 Canvas data

Figure 1: Warning about site trying to extract html5 canvas image data.

Et tu, GitHub?

Tor Browser Warning

Figure 2: Warning about GitHub attempting to extract HTML5 canvas image data.

Second: Some websites can’t tell if I’m human or not, so they ask me to prove it by jumping though a reCAPTCHA loop. Am I legit?

tor Borwser reCAPTCHA

Figure 3: Hacker News asking me to prove if I’m legit.

Some will go a step further and tell you what you can do to prevent being asked to jump through a reCAPTCHA barrier in the future.

Tor Browser virus scan

Figure 4: What I can do to prevent getting a reCAPTCHA.

Note that Tor Browser is a patched version of Firefox, but these are things I’ve never encountered while using plain-vanilla Firefox or even Chromium. I wonder what other tricks these website’s try to pull when you’re not using Tor Browser. For more on HTML5 canvas image data and other features in Tor Browser, visit Fingerprinting defenses in the Tor Browser.