FP-Block 2

Installation

Requires Firefox Developer or Nightly edition.
Go to about:config (enter in address bar) and set xpinstall.signatures.required to false.

Windows

1. Open the directory containing the extension in File Explorer
2. Select all files and directories excluding .git
3. Right click to open the shortcut menu, click Send to > Compressed (zipped) folder

Linux / Mac OS X

1. Open a terminal window
2. Navigate to the directory containing the extension, using the command cd path/to/extension/
3. ZIP the content of the directory, using the command zip -r -FS ../FP-Block2.zip * --exclude *.git*

Go to about:addons (enter in address bar), click on the settings wheel followed by Install Add-on From File... and select the ZIP file created during the previous step.

How to spoof/block a property of a web browser

In order to spoof or block a property of a web browser, add its information to one or two files:

• constants.js in the folder src/utils/
• injectedScript.js in the folder src/modules/

The information to add:

• the name of the property
• access type: the way in which the property should be overwritten. The access types supported by FP-Block 2.0 are 'objectProperty' (<object>.<property>) and 'prototypeProperty' (<object>.<prototype>.<property>).
• value type: the type of return value of the properties' getter-method. The value types supported by FP-Block 2.0 are 'string', 'number', 'array', 'storageObject', and 'object'.
• function names, only for storage objects.

If a spoof/block property is handled in the standard manner of injectedScript.js, then the information should be added only in constants.js, otherwise you also need to adjust injectedScript.js. There are two special cases that are handled separately:

• preventing against canvas fingerprinting, since there is no standard manner to overwrite functions in FP-Block 2.0
• preventing against font probing, since there are limitations to calling detection, using a special variable to improve the performance of the plug-in

constants.js

1. If a property should be spoofed, add its name to SPOOF_ATTRIBUTES
2. If the corresponding DOM-object does not exist in DOM_OBJECTS, add the object
3. Add the properties' information to DOM_OBJECTS in the corresponding object like navigator or screen.

In FP-Block 2.0, the information of properties to change by preventing font detection and canvas fingerprinting have their own constants.

How to increase the amount of fingerprints

The default number of fingerprints used by FP-Block 2.0 is 480480. If more fingerprints are needed, the amount of combinations can be increased by uncommenting languages in data/browser_data.js.