CanvasFingerprintBlock

CanvasFingerprintBlock插件简介

CanvasFingerprintBlock插件描述

IMPORTANT: If the extension does not wk on a specific site, please post the details in the SUPPORT section, as this will help me fix it. It is pointless to complain that it doesn’t wk without posting the details. Thank you.

RELEASES

Version 1.5 (2016Mar06)
  • Updated scriptinjection technique so that it wks also on pages with strict CSP.

Version 1.4 (2016Mar05)
  • Extension was (unnecessarily) trying to patch functions in a crossigin frame (like Hangouts frame in GMail, Disqus frame in several sites, etc.) from within the outer window. This was breaking the sites’ functionality; now this is avoided.

Version 1.3 (2016Feb28)
  • Blocked iframe[@sbox] canvas reads are now shown properly inside popup
  • Me detailed infmation per blocking

Version 1.2 (2016Feb27)
  • Now also blocks read attempts from canvas inside a sboxed iframe element

DETAILS

Canvas Fingerprinting is one of latest technologies being adopted by websites to track visits without using cookies. Such websites do this by painting an image on a hidden HTML  element  then taking a snapshot of it  posting the snapshot back to themselves. Because the exact pixel values in the drawn canvas can differ subtly from one set of hardware to another, these websites can use those differences to distinguish  visits as well as to recognize specific visits from one visit to the next. Which is what tracking cookies are nmally used f, except that cookies may be disabled  deleted  avoided by browsing in Incognito mode, whereas to avoid Canvas Fingerprinting you need to use a tool like CanvasFingerprintBlock.

The HTML  element exposes two types of JavaScript functions: functions to draw to the canvas,  functions to expt data from the canvas (f the nerds, these are toDataURL()  getImageData()). The canvasdrawing functions are not affected by CanvasFingerprintBlock, so websites that use the canvas f basic drawing will not be affected. On the other h, when a website tries to expt data from the canvas, CanvasFingerprintBlock will “fool” the website by showing it a blank canvas instead of the canvas containing the actual pixels. If the website is reading the canvas data to generate a fingerprint, the generated fingerprint will be useless because CanvasFingerprintBlock makes everyone’s fingerprint look the same.

If a little red fingerprint icon appears in the address bar beside the Bookmark ☆ icon, it means that the website you are visiting has tried to access the data of at least one canvas,  CanvasFingerprintBlock has blocked it. You will be surprised to discover how many websites employ Canvas Fingerprinting! Most websites are quite sneaky in how they create the fingerprint; the canvas is always hidden,  usually the canvas would have already been created, read  removed by the time the website has finished loading! Of course you will be curious to inspect what was being drawn right under your nose,  CanvasFingerprintBlock will let you see it by clicking on the little red fingerprint icon.

Lastly, it is notewthy to mention that not all websites that are trying to expt data from a canvas are doing it maliciously. F example, some photo uploaders will let you edit your photo on a canvas  when you are ready will expt the edited photo  upload it to the server. Or some other websites will use a “rough” canvas to draw a gradient  pattern,  will then expt the canvas to use that pattern somewhere else on the page. When you see the little red fingerprint icon, by clicking on it it is usually easy to tell whether the blocked canvas was drawn f fingerprinting purposes  not. However it is not so simple to detect this automatically. So f the time being, CanvasFingerprintBlock will block all canvas data expts,  the only way of allowing a canvas read is to disable the extension temparily. This will be fixed in a future update of CanvasFingerprintBlock.

You may test CanvasFingerprintBlock on this website: http://www.browserleaks.com/canvas

Note: If you are a user of Chrome’s Incognito mode, then to be fully protected it is advisable to enable the CanvasFingerprintBlock extension also in Incognito mode (check “Allow in Incognito”).
                                

CanvasFingerprintBlock插件离线安装方法

1.首先用户点击谷歌浏览器右上角的自定义及控制按钮，在下拉框中选择设置。

2.在打开的谷歌浏览器的扩展管理器最左侧选择扩展程序或直接输入：chrome://extensions/

3.找到自己已经下载好的Chrome离线安装文件xxx.crx，然后将其从资源管理器中拖动到Chrome的扩展管理界面中，这时候用户会发现在扩展管理器的中央部分中会多出一个”拖动以安装“的插件按钮。

4.下载 CanvasFingerprintBlockChrome插件v1.5版本到本地。

5.勾选开发者模式，点击加载已解压的扩展程序，将文件夹选择即可安装插件。

注意：最新版本的chrome浏览器直接拖放安装时会出现“程序包无效CRX-HEADER-INVALID”的报错信息，参照这篇文章即可解决