Canvas Blocker (Fingerprint Protect) Do not allow HTML5 Canvas element from generating a unique identification key for your browser
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The "Canvas Blocker" extension alters two frequently used methods of the HTML5 Canvas element that typically create an individual fingerprint key for your browser. The extension's objective is to prevent websites from creating a unique identifier by making slight adjustments to the image data. Users are alerted through desktop notifications whenever a suspicious method is used. It employs a non-persistent background page, ensuring it doesn't impact the browsing experience when not in use. Additionally, compared to similar extensions, it uses a more optimized code to effectively prevent fingerprinting.



  1. What is the "Canvas Blocker (fingerprint protect)" extension?

    The canvas element functions as a virtual canvas within the browser, enabling dynamic drawing of visual objects through JavaScript, greatly enhancing the browsing experience. Regrettably, this element can be exploited by advertising and malicious scripts to identify users and subsequently track their browsing preferences. Essentially, this element serves as a tool to create a distinctive fingerprint unique to each browser. When various pages generate this distinct key and send it to a server, it becomes remarkably easy to monitor a user's browsing patterns.

    One technique to generate a distinct identification key involves overlaying two strings in a slight offset within a canvas element and converting this element into a data string. The resulting string can exhibit slight variations based on the user's operating system and graphical card capabilities, rendering the generated string unique. This lengthy string is then transformed into a condensed, unique key using a hashing method such as the SHA algorithm.

    This extension introduces an arbitrary one-time distortion to the canvas element solely when one of the string conversion methods is invoked. To streamline the application of this distortion and enhance its speed, the extension applies the distortion selectively, spacing it at points with intervals of three elements within the canvas. This approach significantly reduces the computational workload involved in applying the distortion.

  2. How can I disable this extension?

    Typically, there's no necessity to deactivate the extension (if an instance arises, please report it in the review section). From version 0.2.0 onward, an action button is provided to deactivate the extension, yet it's not advisable to use it. Alternatively, you can disable the extension via your browser's extension manager. Also, in Chromium browsers, you can instead use the right-click context menu on the action button to restrict the extension's access to specific websites. This action results in the extension being disabled on all sites except those explicitly permitted access.

  3. What's new in this version?

    Please check the Logs section.

  4. How does this extension differ from other similar ones available?

    Two approaches exist to counteract Canvas fingerprinting. One method involves eliminating Canvas access to the JavaScript engine, while the other manipulates functions that could be exploited for fingerprinting purposes. The former is a secure approach but can reduce the browser's functionalities. The latter, although recommended, is notably more challenging to implement.

    Careful coding is essential for the method that manipulates internal functions to ensure it doesn't impact page performance. This extension is meticulously crafted, considering two crucial factors: 1. Minimizing code application to avoid slowing down the browser unnecessarily. 2. Preventing fingerprinting across all frames, eliminating alternative methods to generate a unique key, even with the use of sandboxed new frame techniques.

  5. Is it possible to deactivate the extension for a specific website?

    Starting from version 0.1.2, you can disable this extension on designated hostnames. You can achieve this by right-clicking on the action button while on the website and choosing the "Disable Fingerprinting" item. Or you can directly input the hostnames within the extension's options page.

  6. Is it possible to receive notifications for detected fingerprinting but disable this feature for specific websites?

    For websites where you prefer not to receive notifications, you can right-click the action button and opt for the "Disable Notification" entry. Additionally, you can directly input the hostname into the options page. If you need to remove a hostname from this list, delete it from the options page and click the "Save Options" button.

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What's new in this version

Change Logs:
    Last 10 commits on GitHub
    Hover over a node to see more details

    Need help?

    If you have questions about the extension, or ideas on how to improve it, please post them on the  support site. Don't forget to search through the bug reports first as most likely your question/bug report has already been reported or there is a workaround posted for it.

    Open IssuesIssuesForks

    Permissions are explained

    *://*/*to be able to access all domains (to be able to inject fingerprint blocker script to all domains)
    notificationsto notify the user when a fingerprint attempt is reported
    storageto save internal preferences

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